Vitamin B3 (niacin)

Nicotinic acid and nicotinamide (niacinamide) · also called Niacin, vitamin B3, nicotinic acid, nicotinamide, niacinamide

Vitamin B3, or niacin, is a B vitamin your body needs to turn food into energy. Most people get enough from food, and a severe lack causes a disease called pellagra. High-amount nicotinic acid changes blood fats but did not prevent heart attacks in large trials, and it can cause flushing, liver injury and higher blood sugar. Ask a doctor or pharmacist before taking more than a multivitamin contains.

General information, not medical advice. Last substantive update October 26, 2026 · Not medically reviewed. A named clinician has not signed off on this page. How this page is made

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About Vitamin B3 (niacin)

Niacin is vitamin B3. It comes in two forms, nicotinic acid and nicotinamide, and both are in food. You need it every day because the body does not store it. Most people eat enough. The best-supported uses are preventing and treating deficiency. High-amount nicotinic acid changes cholesterol numbers but not heart outcomes, and it has real risks.

What it is

Niacin is a water-soluble B vitamin. The body builds it into NAD and NADP, helpers that release energy from food, and it helps the digestive system, skin and nerves work (MedlinePlus, NHS). It is not stored, and extra leaves in the urine.

The body can also make some niacin from the amino acid tryptophan, at about 60 mg of tryptophan for 1 mg of niacin. Because of this, the official allowances count "niacin equivalents". The rate differs a lot between people.

Two forms matter: nicotinic acid (causes flushing and changes blood fats at high amounts) and nicotinamide, also called niacinamide (does not cause flushing). Inositol hexanicotinate is a "flush-free" form that is absorbed about 30% less well on average. NMN and nicotinamide riboside are different compounds, not covered here.

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Food sources (what is in food)

NIH lists niacin per serving, in mg: beef liver (3 oz) 14.9, chicken breast (3 oz) 10.3, turkey breast (3 oz) 10.0, sockeye salmon (3 oz) 8.6, light tuna in water (3 oz) 8.6, pork tenderloin (3 oz) 6.3, ground beef (3 oz) 5.8, brown rice (1 cup) 5.2, dry-roasted peanuts (1 oz) 4.2, enriched white rice (1 cup) 2.3, a baked potato 2.3, whole-wheat bread (1 slice) 1.4, lentils (half a cup) 1.0, plain low-fat yogurt (1 cup) 0.3. The label Daily Value is 16 mg.

Animal foods give niacin in forms that are well absorbed. In many plant foods and grains it is partly bound, with only about 30% available, unless the grain is enriched or specially prepared (soaking corn in limewater frees it). Turkey and other protein foods also give tryptophan the body can convert. Food amounts describe the food and are not advice on how much to eat.

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What the research shows

Deficiency: pellagra is cured by niacin under a clinician, according to MedlinePlus, ODS and the WHO (as reported by ODS). No modern trial was read, and the benefit applies to people who are truly deficient.

Blood fats and the heart: medicine-level nicotinic acid raised HDL and lowered triglycerides and LDL. A Cochrane review of 23 trials (39,195 people) and two very large trials found no fewer heart attacks, strokes or deaths, and more side effects. US heart groups, as reported by ODS, do not recommend adding niacin to a statin.

Skin cancer: nicotinamide lowered new non-melanoma skin cancers by 23% in one trial of high-risk people, had no effect in transplant recipients, and was not significant when pooled. Type 1 diabetes: no benefit in at-risk relatives.

Everyday benefits in people who are not deficient have not been tested in trials we found.

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Food versus supplements

The trials on cholesterol, skin cancer and type 1 diabetes used pure nicotinic acid or nicotinamide at amounts far above food, and their results do not apply to food. Food niacin has no reported harm. Fortified foods contain the free, well-absorbed form. Multivitamins contain small amounts; single-ingredient niacin products can contain much more than the RDA.

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At a glance

Traditional uses history, not proof

Needed in the diet to prevent pellagra, which was common in the early 1900s among people living mostly on corn
Soaking corn in limewater (as for tortillas) frees its niacin

Studied for research

Correcting niacin deficiency (pellagra), moderate certainty (agency consensus; no trial read)
Blood fats at medicine-level nicotinic acid, high certainty for the lab numbers
Heart attacks, strokes and death, evidence against a benefit (23 trials)
Non-melanoma skin cancer with nicotinamide, mixed evidence
Preventing type 1 diabetes in at-risk relatives, evidence against (one large trial)
Extra energy, skin or nerve health in people who get enough, not enough evidence

Main compounds

Nicotinic acid
Nicotinamide (niacinamide)
NAD (the coenzyme niacin is built into)
Inositol hexanicotinate ("flush-free" form)

Common forms

Niacin from food (meat, fish, grains, nuts; enriched breads and cereals)
Nicotinic acid supplements and prescription extended-release niacin (flushing)
Nicotinamide supplements (no flushing; used in the skin-cancer trials)
Inositol hexanicotinate, NMN and nicotinamide riboside are different products and are not covered in depth

Research links: 2017 Cochrane review: niacin and heart events (23 trials) · 2015 trial: nicotinamide and skin cancer · NIH Office of Dietary Supplements: niacin fact sheet · Research Library · Genes & Biomarkers Library

What it is and its history

Accepted scientific name: Vitamin B3 (niacin). Not a species: a water-soluble vitamin that covers two chemical forms, nicotinic acid and nicotinamide.
Common names: Niacin (English); Vitamin B3 (English); Nicotinic acid (English); Nicotinamide (English); Niacinamide (English (US))
Family or group: B-complex vitamins (water-soluble)
Harvest and processing: Niacin is added to enriched breads, cereals and infant formulas in the United States and many other countries; added niacin is in its free form and is well absorbed (ODS). Supplements come as nicotinic acid, nicotinamide or inositol hexanicotinate, alone or in multivitamins and B-complex products.
Look-alikes and adulterants: Name: Nicotinamide riboside and NMN; Note: Niacin-related compounds sold as supplements. ODS says they are not marketed as niacin sources, and that the FDA ruled in November 2022 that NMN may not be sold as a dietary supplement. Not covered here.; Name: Tryptophan; Note: An amino acid the body can convert into niacin, at roughly 60 mg of tryptophan for 1 mg of niacin (ODS). Not the same as niacin.; Name: Inositol hexanicotinate; Note: A "flush-free" niacin ester; absorbed about 30% less well on average than nicotinic acid or nicotinamide (ODS).

Traditional use and history history, not clinical proof

Tradition or era	Documented use	Source
Late 1950s onward	Studies since the late 1950s showed that very high amounts of nicotinic acid raise HDL and lower LDL and triglycerides (ODS).	s-ods-niacin
Early 20th century, southern United States and parts of Europe	Pellagra was not uncommon among people living in poverty on diets of mainly corn (ODS).	s-ods-niacin
Central America, traditional cooking	Soaking corn in limewater overnight, as in the making of tortillas, releases the niacin that is otherwise tightly bound; pellagra is rare where this is done (MedlinePlus).	s-medlineplus-pellagra
1970s	A large trial (8,341 people who had had heart attacks) tested 3,000 mg a day of nicotinic acid against placebo for about 6 years, with fewer non-fatal heart attacks but no fall in deaths during treatment; 9 years after it ended, the niacin group had fewer deaths (ODS, second-hand).	s-ods-niacin

Traditional use shows how it was used. It does not show that it works or is safe today.

What is inside, and how it may work

What it contains and how those compounds act in cells and animals. Laboratory and animal mechanisms are not proven effects in people.

Main compounds

Compound	Family	Where it is concentrated	Activity studied	Level of evidence
Nicotinic acid PubChem 938	vitamin (pyridinecarboxylic acid)	Plant foods such as nuts, legumes and grains give about 2 to 5 mg niacin per serving, mainly as nicotinic acid (ODS).	Causes skin flushing at supplement amounts and, at medicine-level amounts, changes blood fats. Binds receptors that mediate those effects. ^{14 1 6}	Human data
Nicotinamide (niacinamide) PubChem 936	vitamin (pyridinecarboxamide)	Animal foods such as poultry, beef and fish give about 5 to 10 mg niacin per serving, mostly in forms such as NAD and NADP (ODS).	Does not cause flushing and does not change blood fats the way nicotinic acid does. Used in the skin-cancer and type 1 diabetes trials. ^{14 3 2 4}	Human data
NAD (nicotinamide adenine dinucleotide) PubChem 5893	coenzyme	Not given	The coenzyme into which dietary niacin is built; takes part in releasing energy from food. ¹⁴	Lab

Mechanisms, receptors and pathways

Target or pathway	Gene or receptor	What was found	Level
NAD and NADP production	Not specified in the sources read	Niacin and tryptophan are used to make the coenzymes NAD and NADP, which take part in turning food into energy. Conversion of tryptophan needs riboflavin, vitamin B6 and iron (ODS). ^{14 11}	Human data
Blood fat control by nicotinic acid	A receptor that nicotinic acid binds (not named in the sources read)	ODS says nicotinic acid binds receptors that mediate its effects on blood fats, and nicotinamide does not. ¹⁴	Human data
Flushing	Not specified	ODS says flushing comes from widening of small blood vessels under the skin. ¹⁴	Human data
UV-damage repair in skin (nicotinamide)	Not specified	The skin-cancer trial papers state, as background, that nicotinamide helps repair UV-damaged DNA and reduces UV's immune-suppressing effect. This was not tested in the trials read. ^{3 2}	Lab

Absorption, metabolism and elimination

Absorption: Nicotinic acid and nicotinamide are almost completely absorbed. Inositol hexanicotinate is absorbed about 30% less well on average. In some grains, niacin is bound and only about 30% available (ODS).
Distribution: Not found.
Metabolism: Leftover niacin is not stored; the body keeps a small reserve (MedlinePlus). The conversion of tryptophan to niacin varies a lot between people (ODS).
Elimination: Excess water-soluble vitamin leaves in the urine (MedlinePlus).
Bioavailability: Added (free) niacin in enriched foods is well absorbed; bound niacin in unprocessed grains is not (ODS).

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Isolated compounds versus whole extracts

Food niacin is the form that has no reported harm. The trials on blood fats, skin cancer and type 1 diabetes all used pure nicotinic acid or nicotinamide at medicine-level amounts, far above food. Their results do not apply to food, and food-level amounts are not shown to give those effects. Animal foods give niacin in forms that are well absorbed; plant foods mostly give nicotinic acid, and in many grains it is only partly available unless the grain is enriched or specially prepared.

Nutritional composition

Food amounts are from the ODS fact sheet (which takes them from USDA FoodData Central), read 2026-10-26 through an archive copy. Niacin per serving, in mg: beef liver, pan fried, 3 oz 14.9; chicken breast, grilled, 3 oz 10.3; turkey breast, roasted, 3 oz 10.0; sockeye salmon, cooked, 3 oz 8.6; light tuna in water, 3 oz 8.6; pork tenderloin, roasted, 3 oz 6.3; 90% lean ground beef, 3 oz 5.8; brown rice, cooked, 1 cup 5.2; dry-roasted peanuts, 1 oz 4.2; cereal fortified with 25% DV, about 4.0; enriched white rice, cooked, 1 cup 2.3; baked russet potato, 1 medium 2.3; dry-roasted sunflower seeds, 1 oz 2.0; whole-wheat bread, 1 slice 1.4; enriched white bread, 1 slice 1.3; boiled lentils, half cup 1.0; banana, 1 medium 0.8; plain low-fat yogurt, 1 cup 0.3; 1% milk, 1 cup 0.2; large egg 0. The Daily Value used on labels is 16 mg for adults and children aged 4 and over. These values count niacin only, not the niacin the body can make from tryptophan. Turkey breast (3 oz) has about 180 mg of tryptophan, equal to about 3 mg of niacin. These numbers describe foods and are not advice on how much to eat.

6benefits and uses looked at

14studies and sources checked

High certaintybest evidence rating found

5lab markers tracked in trials

1 high certainty1 moderate certainty1 mixed findings1 not enough evidence2 evidence against

What was looked at

The 6 benefits and uses checked for Vitamin B3 (niacin), each with how strong the evidence is. Tap one to open it.

Correcting niacin deficiency (pellagra)Moderate certainty
Blood fats: HDL, LDL and triglycerides (medicine-level nicotinic acid)High certainty
Heart attacks, strokes and deathEvidence against
Non-melanoma skin cancer in high-risk people (nicotinamide)Mixed findings
Preventing type 1 diabetes in at-risk relatives (nicotinamide)Evidence against
Everyday energy, skin and nerve health in people who already get enoughNot enough evidence

Lab markers tracked in the studies

HDL cholesterol (the "good" cholesterol)LDL cholesterol (the "bad" cholesterol)TriglyceridesActinic keratoses (rough, pre-cancerous skin patches)New diagnosis of diabetes (a harm signal)

What is Vitamin B3 (niacin) good for?

The main studied uses and how strong the human evidence is for each. Most trials used pure nicotinic acid or nicotinamide at medicine-level amounts, far above what food gives, so they do not describe food niacin.

Correcting niacin deficiency (pellagra)Moderate certaintyA severe lack of niacin causes pellagra: diarrhoea, scaly skin sores in sunlit areas and confusion. NIH, MedlinePlus and the WHO (as reported by NIH) treat it with niacin or nicotinamide under a clinician, and people often do well. No modern trial was read. It does not show a benefit for people who already get enough. Blood fats: HDL, LDL and triglycerides (medicine-level nicotinic acid)High certaintyIn 3414 people on a statin, extended-release niacin raised median HDL from 35 to 42 mg/dL and lowered triglycerides from 164 to 122 mg/dL and LDL from 74 to 62 mg/dL after 2 years. In 25,673 people, LDL was 10 mg/dL lower and HDL 6 higher. These are lab numbers only. Both big trials were funded in part by makers of niacin medicines. Heart attacks, strokes and deathEvidence againstA Cochrane review of 23 trials (39,195 people) found niacin did not reduce total death (RR 1.05), heart attacks (RR 0.93, 0.87 to 1.00) or strokes (RR 0.95), and people on niacin were more likely to stop for side effects (RR 2.17). Two very large trials agreed. The authors say benefits are unlikely. Non-melanoma skin cancer in high-risk people (nicotinamide)Mixed findingsIn 386 people with repeated skin cancers, nicotinamide by mouth gave 23% fewer new non-melanoma skin cancers over 12 months (95% CI 4 to 38), with no benefit after stopping. In 158 transplant recipients there was no effect (rate ratio 1.0). A pooled analysis of 4 studies was not significant (RR 0.82, 0.61 to 1.12). Preventing type 1 diabetes in at-risk relatives (nicotinamide)Evidence againstIn 552 relatives of people with type 1 diabetes, 5 years of high-amount nicotinamide did not change who developed diabetes (82 vs 77 people; HR 1.07, 0.78 to 1.45). Everyday energy, skin and nerve health when intake is already enoughNot enough evidenceNiacin does help the body release energy and supports skin, nerves and digestion. But no trial was found showing that extra supplements add anything when you already get enough. A gap in the evidence, not proof of no effect.

Benefits, one by one

Each card is a research question, not a promise. Tap a goal to filter. Open a card to see the studies, doses and limits.

Correcting niacin deficiency (pellagra)

Moderate certainty

A severe lack of niacin causes pellagra: diarrhoea, scaly skin sores in sunlit areas, and confusion. Health agencies say it is treated with niacin supplements chosen by a clinician, and that people often do well. We found no modern trial of this. It rests on long clinical experience and agency statements.

3 studiesNiacin (nicotinic acid) or nicotinamide, chosen and directed by a cli…

Studies, doses and limits

What the trials found

No trial was read. MedlinePlus (reviewed 2024) says treatment is niacin supplements, with any underlying cause treated too, and that people often do well. ODS says the World Health Organization recommends treating pellagra with nicotinamide plus a B-complex or yeast product, because other B vitamins are usually low too. A 2004 clinical review describes the rash as sunburn-like, worse in sunlight, and notes that diagnosis is hard without skin lesions.

Results

Established in medical practice for people who are truly deficient. The benefit does not carry over to people who already get enough.

Effect sizes as reported

No effect sizes: no trial was found in the sources read.

Why this rating

Moderate. Strong, consistent statements from NIH, MedlinePlus and the WHO (as reported by ODS) and a long clinical record, but no modern controlled trial was read. A trial would be unethical in severe deficiency.

Form and dose studied

Niacin (nicotinic acid) or nicotinamide, chosen and directed by a clinician. Food and enriched grains prevent it.

Who was studied

People who are deficient: poor diets, alcohol use disorder, bowel disease, weight-loss surgery, carcinoid syndrome, Hartnup disease, or some medicines such as isoniazid.

Limits

This is not evidence that extra niacin helps anyone who already gets enough. Self-treating suspected pellagra can delay finding the cause.

Why researchers looked

Niacin was identified through pellagra, which was common in the early 20th century among people living on corn-heavy diets. Today it is rare in rich countries and is seen with severe alcohol misuse, bowel disease, weight-loss surgery, some medicines and poor diets.

Traditional use

Pellagra was widespread in the southern United States and parts of Europe in the early 1900s. In Central America, soaking corn in limewater to make tortillas frees niacin, and pellagra is rare there (MedlinePlus).

Proposed mechanism Authoritative guidance

Niacin is built into NAD and NADP, helpers the body uses to release energy from food. The body can also make some niacin from the amino acid tryptophan, at about 60 mg of tryptophan for 1 mg of niacin, and this varies a lot between people (ODS).

A proposed mechanism does not show that the effect happens in people.

Left untreated, pellagra can cause nerve damage, especially in the brain, and death (MedlinePlus). See a clinician for symptoms.

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Blood fats: HDL, LDL and triglycerides (medicine-level nicotinic acid)

High certainty

Nicotinic acid taken at medicine-level amounts, far above food levels, reliably moves blood fats: HDL up, LDL and triglycerides down. Nicotinamide does not. The change is modest next to statins, and it did not turn into fewer heart attacks (see the next row).

4 studiesExtended-release nicotinic acid with or without a flushing-blocker dr…

Studies, doses and limits

What the trials found

In AIM-HIGH (3414 people with heart disease, all on simvastatin), extended-release niacin raised median HDL from 35 to 42 mg/dL, lowered triglycerides from 164 to 122 mg/dL and LDL from 74 to 62 mg/dL after 2 years. In HPS2-THRIVE (25,673 people), niacin with laropiprant lowered LDL by 10 mg/dL and raised HDL by 6 mg/dL compared with placebo. ODS summarises studies since the 1950s as HDL up 10% to 30%, LDL down 10% to 25%, triglycerides down 20% to 50%.

Results

Real, consistent changes in blood tests at medicine-level amounts of nicotinic acid, about 100 times the RDA or more per ODS. The tests moved; heart outcomes did not follow.

Effect sizes as reported

AIM-HIGH at 2 years: HDL 35 to 42 mg/dL, triglycerides 164 to 122 mg/dL, LDL 74 to 62 mg/dL (medians). HPS2-THRIVE: LDL 10 mg/dL lower, HDL 6 mg/dL higher. ODS range summary: HDL +10% to 30%, LDL -10% to 25%, triglycerides -20% to 50%.

Why this rating

High that the blood-test numbers change, from two very large randomised trials and a long record. This is a statement about lab markers only, not about health outcomes.

Form and dose studied

Extended-release nicotinic acid with or without a flushing-blocker drug in the trials; the amounts are in the studies table.

Who was studied

Adults with established cardiovascular disease and already on statins.

Limits

Both big trials added niacin to a statin. Results for people not on a statin come from older, smaller trials. Both trials were funded in part by makers of niacin medicines (Abbott, Merck).

Why researchers looked

Nicotinic acid has been tested for blood fats since the late 1950s, because HDL ("good") cholesterol is low and triglycerides high in many people with heart disease.

Proposed mechanism Authoritative guidance

ODS says nicotinic acid binds receptors that mediate its effects on blood fats, and nicotinamide does not. The trials read did not test the mechanism.

A proposed mechanism does not show that the effect happens in people.

Flushing, high blood sugar, liver injury and other problems at these amounts. See the Safety tab. Talk to a clinician before starting.

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Heart attacks, strokes and death

Evidence against

Despite better HDL, LDL and triglyceride numbers, niacin did not reduce heart attacks, strokes or deaths in a Cochrane review of 23 trials, and it caused more side effects. Heart groups do not recommend adding it to a statin.

4 studiesMostly extended-release nicotinic acid in pharmacological amounts, ad…

Studies, doses and limits

What the trials found

The 2017 Cochrane review pooled 23 randomised trials (39,195 people; median 2 g a day for about 11.5 months). Niacin did not reduce total death (RR 1.05), cardiovascular death (RR 1.02), heart attacks (RR 0.93, 0.87 to 1.00) or strokes (RR 0.95). People on niacin were about twice as likely to stop treatment because of side effects (RR 2.17). AIM-HIGH found no difference in a combined heart outcome (16.4% niacin vs 16.2% placebo, HR 1.02) and HPS2-THRIVE found none (rate ratio 0.96), with more serious side effects on niacin-laropiprant. ODS notes an older 1970s trial found fewer non-fatal heart attacks, but no fall in deaths during treatment.

Results

Evidence against a benefit for preventing heart attacks, strokes or death. The authors of the Cochrane review say benefits are unlikely.

Effect sizes as reported

Cochrane: total death RR 1.05 (0.97 to 1.12); heart attacks RR 0.93 (0.87 to 1.00); strokes RR 0.95 (0.74 to 1.22); stopping for side effects RR 2.17 (1.70 to 2.77). AIM-HIGH HR 1.02 (0.87 to 1.21). THRIVE rate ratio 0.96 (0.90 to 1.03).

Why this rating

Against a benefit. Moderate- to high-quality evidence from a Cochrane review (23 trials) and two very large trials all point the same way: no reduction in events.

Form and dose studied

Mostly extended-release nicotinic acid in pharmacological amounts, added to statins.

Who was studied

Adults with or at risk of cardiovascular disease, most already on a statin.

Limits

Says nothing about food niacin or correcting deficiency. Industry funding in the two big trials (Abbott for AIM-HIGH; Merck for HPS2-THRIVE).

Why researchers looked

If niacin improves blood fats, it might prevent heart attacks. Dozens of trials have tested this.

Proposed mechanism Hypothesis

Not tested. The lab changes were expected to lower risk, but that did not happen in the trials.

A proposed mechanism does not show that the effect happens in people.

More diabetes, stomach and bowel problems, muscle and bone problems, infections and bleeding in HPS2-THRIVE. See the Safety tab.

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Non-melanoma skin cancer in high-risk people (nicotinamide)

Mixed findings

One trial found that nicotinamide (niacinamide) by mouth cut new non-melanoma skin cancers by about a quarter in people who had already had several. A later trial in transplant patients found no effect, and a pooled analysis found the overall evidence not significant. Results are mixed and the effect did not last after stopping.

3 studiesOral nicotinamide (niacinamide), not nicotinic acid, in the trials. T…

Studies, doses and limits

What the trials found

ONTRAC (386 adults with at least two non-melanoma skin cancers in 5 years): 500 mg of nicotinamide twice a day for 12 months gave 23% fewer new cancers (95% CI 4 to 38; P=0.02) than placebo. Squamous-cell cancers were 30% fewer (borderline, P=0.05), basal-cell 20% fewer (not significant), and actinic keratoses (pre-cancer patches) 11% to 20% fewer. There was no benefit after stopping. ONTRANS (158 organ-transplant recipients, stopped early): 207 new cancers on nicotinamide vs 210 on placebo (rate ratio 1.0, 0.8 to 1.3). A 2023 pooled analysis of 4 studies found no significant effect on non-melanoma skin cancer overall (RR 0.82, 0.61 to 1.12) and concluded the evidence was insufficient.

Results

Mixed. A benefit in one good trial of people with normal immunity; none in transplant recipients; not significant when pooled.

Effect sizes as reported

ONTRAC: 23% fewer new non-melanoma skin cancers (4% to 38%). ONTRANS: rate ratio 1.0 (0.8 to 1.3). Pooled: RR 0.82 (0.61 to 1.12).

Why this rating

Mixed. One positive phase 3 trial, one negative phase 3 trial in a different group (stopped early) and a pooled analysis that was not significant.

Form and dose studied

Oral nicotinamide (niacinamide), not nicotinic acid, in the trials. The amounts used are in the studies table. This is not about skin creams.

Who was studied

Adults with repeated skin cancers; immunosuppressed organ-transplant recipients in ONTRANS.

Limits

Small numbers of trials. Not shown to prevent skin cancer in people at average risk, and sun protection and skin checks are not replaced. Both main trials were publicly funded.

Why researchers looked

Lab work suggests nicotinamide helps skin repair damage from sunlight (UV). The trials ask whether that lowers new skin cancers in people at high risk.

Proposed mechanism Laboratory research

The trial papers state, as background, that nicotinamide helps repair UV-damaged DNA and reduces the immune-suppressing effect of UV on skin. The trials did not test this.

A proposed mechanism does not show that the effect happens in people.

No noteworthy differences in side effects in either trial. Nicotinamide at these amounts is a medicine-level use; ask a skin doctor.

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Preventing type 1 diabetes in at-risk relatives (nicotinamide)

Evidence against

A large 5-year trial in 552 relatives of people with type 1 diabetes found that high-amount nicotinamide did not stop diabetes from developing.

1 studiesModified-release nicotinamide; amount in the studies table.

Studies, doses and limits

What the trials found

In ENDIT, 552 relatives with islet-cell antibodies took modified-release nicotinamide (1.2 g per square metre of body surface per day) or placebo for 5 years. Diabetes developed in 82 on nicotinamide and 77 on placebo (HR 1.07, 0.78 to 1.45). Serious side effects did not differ, growth in children was unaffected, and 30.4% withdrew.

Results

No benefit at the amount tested.

Effect sizes as reported

HR 1.07 (0.78 to 1.45); adjusted HR 1.01 (0.73 to 1.38).

Why this rating

Against, from one large well-run randomised trial with a clear null result. It is one trial at one amount, so other approaches are not ruled out.

Form and dose studied

Modified-release nicotinamide; amount in the studies table.

Who was studied

First-degree relatives of people with type 1 diabetes, with islet-cell antibodies and no diabetes yet.

Limits

A single trial from 2004. It does not address people who already have diabetes.

Why researchers looked

Nicotinamide protected against autoimmune diabetes in animal models, so a large trial tested it in people at risk.

Proposed mechanism Animal research

The trial paper says that in animals nicotinamide may work by blocking a DNA-repair enzyme and preventing loss of NAD in insulin-making cells. This did not translate to people.

A proposed mechanism does not show that the effect happens in people.

Serious adverse events did not differ between groups.

⁴

Everyday energy, skin and nerve health in people who already get enough

Not enough evidence

Niacin does help the body release energy and keeps skin, nerves and the digestive system working. But we found no trial showing that extra niacin supplements add energy or improve skin or nerves in people who already get enough from food.

3 studiesNot applicable.

Studies, doses and limits

What the trials found

MedlinePlus and the NHS say niacin helps the body release energy from food and keeps the nervous system, skin and digestive system healthy. ODS says most people in the US already eat more than the RDA: in one survey only 1% of adults were below the average requirement. No trial of niacin supplements for energy, mood or skin in well-fed people was found in the sources read.

Results

No evidence of extra benefit when intake is already enough. A gap in the research, not proof of no effect.

Why this rating

Insufficient. The roles are well described by agencies, but no trial tests extra niacin in people who are not deficient.

Who was studied

Healthy adults who eat a varied diet.

Limits

This row describes nutrition roles, not a tested benefit.

Why researchers looked

Niacin is a basic nutrient, so people often take it hoping for more energy. Agencies describe its normal roles, which are not the same as a benefit from extra pills.

Proposed mechanism Authoritative guidance

Niacin becomes NAD and NADP, which take part in turning food into energy (NHS, MedlinePlus, ODS). Described, not tested here.

A proposed mechanism does not show that the effect happens in people.

High amounts of nicotinic acid cause flushing and other effects. See the Safety tab.

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Connections to the rest of health

How Vitamin B3 (niacin) connects to the rest of our health knowledge graph. Every link says what kind of connection it is. A safety link (for example to the liver) is a warning, not a benefit. A study that merely mentions a topic never creates a benefit link.

Explore every connection: goals, body systems, organs, symptoms, genes

Kind of connection Connected to Search

A. Wellness goals

Connected to	Kind of connection	Evidence status	Context	Studies
Balanced Nutrition	Demonstrated clinical effect	Moderate certainty	Correcting niacin deficiency (pellagra): A severe lack of niacin causes pellagra: diarrhoea, scaly skin sores in sunlit areas, and confusion. Health agencies say it is treated with niacin supplements chosen by a clinician, and that people often do well. We found no modern trial of this. It rests on long clinical experience and agency statements.	^{12 14 7}
Preventive Wellness	Demonstrated clinical effect	Moderate certainty	Correcting niacin deficiency (pellagra): A severe lack of niacin causes pellagra: diarrhoea, scaly skin sores in sunlit areas, and confusion. Health agencies say it is treated with niacin supplements chosen by a clinician, and that people often do well. We found no modern trial of this. It rests on long clinical experience and agency statements.	^{12 14 7}
Cholesterol Balance	Demonstrated clinical effect	High certainty	Blood fats: HDL, LDL and triglycerides (medicine-level nicotinic acid): Nicotinic acid taken at medicine-level amounts, far above food levels, reliably moves blood fats: HDL up, LDL and triglycerides down. Nicotinamide does not. The change is modest next to statins, and it did not turn into fewer heart attacks (see the next row).	^{1 6 14 11}
Heart Health	Demonstrated clinical effect	High certainty	Blood fats: HDL, LDL and triglycerides (medicine-level nicotinic acid): Nicotinic acid taken at medicine-level amounts, far above food levels, reliably moves blood fats: HDL up, LDL and triglycerides down. Nicotinamide does not. The change is modest next to statins, and it did not turn into fewer heart attacks (see the next row).	^{1 6 14 11}
Heart Health		Evidence against	Heart attacks, strokes and death: Despite better HDL, LDL and triglyceride numbers, niacin did not reduce heart attacks, strokes or deaths in a Cochrane review of 23 trials, and it caused more side effects. Heart groups do not recommend adding it to a statin.	^{9 1 6 14}
Healthy Skin		Mixed findings	Non-melanoma skin cancer in high-risk people (nicotinamide): One trial found that nicotinamide (niacinamide) by mouth cut new non-melanoma skin cancers by about a quarter in people who had already had several. A later trial in transplant patients found no effect, and a pooled analysis found the overall evidence not significant. Results are mixed and the effect did not last after stopping.	^{3 2 10}
Preventive Wellness		Mixed findings	Non-melanoma skin cancer in high-risk people (nicotinamide): One trial found that nicotinamide (niacinamide) by mouth cut new non-melanoma skin cancers by about a quarter in people who had already had several. A later trial in transplant patients found no effect, and a pooled analysis found the overall evidence not significant. Results are mixed and the effect did not last after stopping.	^{3 2 10}
Blood Sugar Balance		Evidence against	Preventing type 1 diabetes in at-risk relatives (nicotinamide): A large 5-year trial in 552 relatives of people with type 1 diabetes found that high-amount nicotinamide did not stop diabetes from developing.	⁴
Energy Boost		Not enough evidence	Everyday energy, skin and nerve health in people who already get enough: Niacin does help the body release energy and keeps skin, nerves and the digestive system working. But we found no trial showing that extra niacin supplements add energy or improve skin or nerves in people who already get enough from food.	^{11 13 14}
Reduce Fatigue		Not enough evidence	Everyday energy, skin and nerve health in people who already get enough: Niacin does help the body release energy and keeps skin, nerves and the digestive system working. But we found no trial showing that extra niacin supplements add energy or improve skin or nerves in people who already get enough from food.	^{11 13 14}
Healthy Skin		Not enough evidence	Everyday energy, skin and nerve health in people who already get enough: Niacin does help the body release energy and keeps skin, nerves and the digestive system working. But we found no trial showing that extra niacin supplements add energy or improve skin or nerves in people who already get enough from food.	^{11 13 14}

B. Body systems

Connected to	Kind of connection	Evidence status	Context	Studies
Digestive System	Biological association	Moderate certainty	Studied for: Correcting niacin deficiency (pellagra)	^{12 14 7}
Integumentary System	Biological association	Moderate certainty	Studied for: Correcting niacin deficiency (pellagra) Studied for: Non-melanoma skin cancer in high-risk people (nicotinamide)	^{12 14 7 3 2 10 11 13}
Nervous System	Biological association	Moderate certainty	Studied for: Correcting niacin deficiency (pellagra) Studied for: Everyday energy, skin and nerve health in people who already get enough	^{12 14 7 11 13}
Cardiovascular System	Biological association	High certainty	Studied for: Blood fats: HDL, LDL and triglycerides (medicine-level nicotinic acid) Studied for: Heart attacks, strokes and death	^{1 6 14 11 9}
Metabolism Weight	Biological association	High certainty	Studied for: Blood fats: HDL, LDL and triglycerides (medicine-level nicotinic acid)	^{1 6 14 11}
Endocrine System	Biological association	Evidence against	Studied for: Preventing type 1 diabetes in at-risk relatives (nicotinamide)	⁴
Metabolic System	Biological association	Not enough evidence	Studied for: Everyday energy, skin and nerve health in people who already get enough	^{11 13 14}

C. Body parts and organs

Connected to	Kind of connection	Evidence status	Context	Studies
Liver	Adverse effect or risk	Documented risk	Enzyme rises, hepatitis and acute liver failure are listed by ODS for months or years of high amounts. Liver enzyme rises, hepatitis and acute liver failure are listed by ODS for months or years of high amounts. Preparation or compound: High-amount nicotinic acid, especially extended release	^{14 13}

E. Health conditions

Connected to	Kind of connection	Evidence status	Context	Studies
Pellagra		Documented	Pellagra is the disease of severe niacin lack; it is treated with niacin under clinician direction. Pellagra is the disease of severe niacin lack and is treated with niacin under a clinician. Preparation or compound: Niacin or tryptophan shortage	^{12 14}
Diabetes	Adverse effect or risk	Documented risk	Higher risk of a new diabetes diagnosis in pooled trials (RR 1.34). Preparation or compound: Nicotinic acid at medicine-level amounts	^{5 6}

I. Biomarkers

Connected to	Kind of connection	Evidence status	Context	Studies
HDL cholesterol (the "good" cholesterol)	Biological association	High certainty	Measured in trials: raised. A lab change is not the same as a health benefit.	^{1 6}
LDL cholesterol (the "bad" cholesterol)	Biological association	High certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{1 6 14}
Triglycerides	Biological association	High certainty	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{1 14}
Actinic keratoses (rough, pre-cancerous skin patches)	Biological association	Mixed findings	Measured in trials: lowered. A lab change is not the same as a health benefit.	^{3 2}
New diagnosis of diabetes (a harm signal)	Biological association	High certainty	Measured in trials: raised. A lab change is not the same as a health benefit.	^{5 6}

K. Biological pathways

Connected to	Kind of connection	Evidence status	Context	Studies
Tryptophan	Preliminary mechanism	Human	Amino acid the body converts to niacin; about 60 mg of tryptophan gives 1 mg of niacin and the rate varies between people. RDAs are stated in niacin equivalents (NE) to count both.	¹⁴
Riboflavin (B2), vitamin B6 and iron	Preliminary mechanism	Human	Needed for the pathway that converts tryptophan to niacin; low intakes lower conversion.	¹⁴
Hartnup disease	Preliminary mechanism	Human	A rare inherited disorder that disturbs absorption of tryptophan and so leaves less to convert to niacin.	¹⁴
Carcinoid syndrome	Preliminary mechanism	Human	In this condition tryptophan is mostly turned into serotonin and not niacin, which can cause niacin shortage.	¹⁴

L. Active compounds

Connected to	Kind of connection	Evidence status	Context	Studies
Nicotinic acid	Biological association	Human	Causes skin flushing at supplement amounts and, at medicine-level amounts, changes blood fats. Binds receptors that mediate those effects.	^{14 1 6}
Nicotinamide (niacinamide)	Biological association	Human	Does not cause flushing and does not change blood fats the way nicotinic acid does. Used in the skin-cancer and type 1 diabetes trials.	^{14 3 2 4}
NAD (nicotinamide adenine dinucleotide)	Biological association	Lab	The coenzyme into which dietary niacin is built; takes part in releasing energy from food.	¹⁴

Each connection is stored with the ingredient, the connected record, the kind of connection, the evidence status, the supporting studies, the preparation or compound involved, and a review date (last reviewed October 26, 2026).

Evidence at a glance: what changed in 5 lab markers

Tap a number to show only those markers. Counts are markers, not people.

Metabolic21 Other11

The evidence

The research centre for Vitamin B3 (niacin). Every record here was checked against PubMed or the publisher's page; we never list a study we have not verified.

Evidence by outcome

Correcting niacin deficiency (pellagra) 3 studies Moderate certainty Blood fats: HDL, LDL and triglycerides (medicine-level nicotinic acid) 4 studies High certainty Heart attacks, strokes and death 4 studies Evidence against Non-melanoma skin cancer in high-risk people (nicotinamide) 3 studies Mixed findings Preventing type 1 diabetes in at-risk relatives (nicotinamide) 1 study Evidence against Everyday energy, skin and nerve health in people who already get enough 3 studies Not enough evidence

Bars show how many studies we found for each outcome, not how well it works. People are added up across trials only (reviews are not added, to avoid double counting).

How we rate evidence

High certainty

Several well-run trials or reviews agree; further research is unlikely to change the picture much.

Moderate certainty

Good trials point the same way, but some doubt remains.

Low certainty

Small, short or inconsistent trials. The finding could change with better research.

Very low certainty

Very little or very weak human data. Treat as a possibility only.

Mixed findings

Trials or reviews disagree with each other.

Not enough evidence

Not enough human research to say either way.

Evidence against

Good research found no benefit, or found harm.

We take the reviewers' own risk-of-bias and GRADE statements where they exist, and otherwise judge from study size, design, consistency, directness and whether a product matches what is sold. Many publications do not make evidence high. Method note: We started from our existing vitamin B3 summary, then read NIH Office of Dietary Supplements (via an archive copy), MedlinePlus and NHS pages, and re-read PubMed abstracts for the trials and reviews. Only abstracts were read for studies. Items we could not verify are flagged in the research gaps.

Study library: every study we checked 14

Design Research type Year from Search

Study	Design	People	Product, dose, length	Result
AIM-HIGH Investigators; Boden 2011 Niacin in patients with low HDL cholesterol levels receiving intensive statin therapy. N Engl J Med · PMID 22085343 · DOI	Randomized trial	3414 Adults with established cardiovascular disease and low HDL cholesterol, all on simvastatin (LDL kept at 40 to 80 mg/dL)	Extended-release niacin (nicotinic acid) added to simvastatin, with ezetimibe if needed Nutrient supplement (pharmacological amounts) 1500 to 2000 mg per day Stopped after a mean of 3 years for lack of efficacy · vs Matching placebo plus the same statin	3414 patients (1718 niacin, 1696 placebo). At 2 years niacin raised median HDL from 35 to 42 mg/dL, lowered triglycerides from 164 to 122 mg/dL and LDL from 74 to 62 mg/dL. The main outcome occurred in 282 patients (16.4%) on niacin and 274 (16.2%) on placebo. Hazard ratio 1.02 for the main outcome (no difference) (95% CI 0.87 to 1.21; P=0.79) Methods, limits and funding Outcomes: First event of death from coronary heart disease, heart attack, ischemic stroke, hospital stay for acute coronary syndrome, or symptom-driven revascularisation; HDL, LDL and triglycerides Limitations: Only people already on a statin with LDL under 70 mg/dL; stopped early; shows nothing about niacin in people who are not on a statin or about food niacin. Funding and conflicts: Funded by the US National Heart, Lung, and Blood Institute and Abbott Laboratories (a maker of a niacin medicine). Read: abstract
Allen 2023 Nicotinamide for Skin-Cancer Chemoprevention in Transplant Recipients. N Engl J Med · PMID 36856616 · DOI	Randomized trial	158 Organ-transplant recipients (immune system suppressed) who had at least two keratinocyte (skin) cancers in the past 5 years	Nicotinamide (niacinamide), taken by mouth Nutrient supplement (pharmacological amounts) 500 mg twice a day 12 months · vs Placebo	The trial stopped early because too few people joined. There were 207 new keratinocyte cancers on nicotinamide and 210 on placebo. No differences were seen in squamous-cell or basal-cell cancers, actinic keratoses, quality of life, or side effects. Rate ratio 1.0 (no difference) (95% CI 0.8 to 1.3; P=0.96) Methods, limits and funding Outcomes: Number of new keratinocyte cancers in 12 months; squamous and basal-cell cancers; actinic keratoses; safety; quality of life Limitations: Small trial that stopped early; it may have been too small to show a modest effect. Funding and conflicts: Funded by the Australian National Health and Medical Research Council. Read: abstract
Chen 2015 A Phase 3 Randomized Trial of Nicotinamide for Skin-Cancer Chemoprevention. N Engl J Med · PMID 26488693 · DOI	Randomized trial	386 Australian adults who had at least two non-melanoma skin cancers in the previous 5 years	Nicotinamide (niacinamide), taken by mouth Nutrient supplement (pharmacological amounts) 500 mg twice a day 12 months, checked for 18 months · vs Placebo	New non-melanoma skin cancers were 23% fewer on nicotinamide than on placebo at 12 months. Basal-cell cancers were 20% fewer (not significant) and squamous-cell cancers 30% fewer (borderline, P=0.05). Actinic keratoses (rough pre-cancerous patches) were 11% to 20% fewer at each check. There was no benefit after nicotinamide was stopped, and no noteworthy differences in side effects. 23% lower rate of new non-melanoma skin cancers (95% CI 4 to 38; P=0.02) Methods, limits and funding Outcomes: Number of new non-melanoma skin cancers (basal-cell plus squamous-cell) in 12 months; actinic keratoses; safety Limitations: One trial in people at high risk of skin cancer; protection did not last after stopping; not tested in people at average risk. Funding and conflicts: Funded by the Australian National Health and Medical Research Council. Read: abstract
Gale 2004 European Nicotinamide Diabetes Intervention Trial (ENDIT): a randomised controlled trial of intervention before the onset of type 1 diabetes. Lancet · PMID 15043959 · DOI	Randomized trial	552 Relatives of people with type 1 diabetes who had islet-cell antibodies but not yet diabetes	Modified-release nicotinamide (niacinamide) Nutrient supplement (pharmacological amounts) 1.2 g per square metre of body surface per day 5 years · vs Placebo	Diabetes developed in 82 people on nicotinamide and 77 on placebo. There was no difference, and serious side effects did not differ. 30.4% of people withdrew from the trial. Hazard ratio 1.07 (no difference) (95% CI 0.78 to 1.45; P=0.69) Methods, limits and funding Outcomes: Whether diabetes developed Limitations: Tested one high amount in at-risk relatives only; says nothing about people who already have diabetes or about other forms of diabetes. Funding and conflicts: Funding is not stated in the abstract. Read: abstract
Goldie 2016 Niacin therapy and the risk of new-onset diabetes: a meta-analysis of randomised controlled trials. Heart · PMID 26370223 · DOI	Systematic review meta analysis	26340 11 randomised trials in people without diabetes, followed on average 3.6 years	Niacin (nicotinic acid) in pharmacological amounts, with or without a statin or laropiprant Nutrient supplement (pharmacological amounts) Varied by study Weighted mean follow-up 3.6 years · vs Control groups	1371 of 26,340 people developed diabetes (725 of 13,121 on niacin; 646 of 13,219 on control). Niacin was linked to a higher risk (RR 1.34), about one extra case of diabetes for every 43 people treated for 5 years. Results were consistent with or without a statin. RR 1.34 for new-onset diabetes (95% CI 1.21 to 1.49) Methods, limits and funding Outcomes: New diagnoses of diabetes Limitations: Trials were designed for heart outcomes, not diabetes; amounts were pharmacological. Funding and conflicts: Funding is not stated in the abstract. Read: abstract
HPS2-THRIVE Collaborative Group; Landray 2014 Effects of extended-release niacin with laropiprant in high-risk patients. N Engl J Med · PMID 25014686 · DOI	Randomized trial	25673 Adults with vascular disease on statin-based LDL-lowering treatment	Extended-release niacin (nicotinic acid) with laropiprant (a drug added to reduce flushing) Nutrient plus a flushing-blocker drug 2 g extended-release niacin with 40 mg laropiprant daily Median 3.9 years · vs Matching placebo	LDL was on average 10 mg/dL lower and HDL 6 mg/dL higher with niacin-laropiprant. Major vascular events occurred in 13.2% (niacin-laropiprant) and 13.7% (placebo). Serious problems with diabetes control rose by 3.7 percentage points, new diabetes diagnoses by 1.3, serious stomach and bowel events by 1.0, muscle and bone events by 0.7, skin events by 0.3, infections by 1.4 and bleeding by 0.7. Rate ratio 0.96 for major vascular events (no significant difference) (95% CI 0.90 to 1.03; P=0.29) Methods, limits and funding Outcomes: First major vascular event (heart attack, coronary death, stroke, arterial revascularisation); LDL and HDL; serious adverse events Limitations: The product also contained laropiprant, so the harms cannot all be pinned on niacin alone; people were first screened for being able to take niacin (a run-in phase). Funding and conflicts: Funded by Merck (the maker of the product) and others. Read: abstract
Hegyi 2004 Pellagra: dermatitis, dementia, and diarrhea. Int J Dermatol · PMID 14693013 · DOI	Narrative review	Review of the clinical picture of pellagra (severe niacin deficiency)	Niacin deficiency (no intervention)	The review describes pellagra as a systemic disease caused by a marked cellular lack of niacin, with the four D features (diarrhoea, dermatitis, dementia, death). It says diagnosis is difficult without skin lesions, that the rash starts as redness that looks like sunburn, and that sunlight makes it worse. Descriptive review; no effect size (Not applicable) Methods, limits and funding Outcomes: Clinical features and diagnosis of pellagra Limitations: A short narrative review; only the abstract was read; it does not test any treatment. Funding and conflicts: Funding is not stated in the abstract. Read: abstract
Minto 2017 Definition of a tolerable upper intake level of niacin: a systematic review and meta-analysis of the dose-dependent effects of nicotinamide and nicotinic acid supplementation. Nutr Rev · PMID 28541582 · DOI	Systematic review meta analysis	11741 47 articles; people with high blood fats or cardiovascular disease, and healthy people	Nicotinic acid and nicotinamide supplements Nutrient supplement Varied by study Varied by study	In healthy people taking nicotinic acid alone, major adverse effects occurred at amounts below 1000 mg a day. The authors say the current upper limits (35 mg a day in the United States and 10 mg a day in Europe for nicotinic acid) may be very cautious and may be worth reconsidering, possibly with separate limits for healthy and unhealthy people. Not a single effect size in the abstract (Not given in the abstract) Methods, limits and funding Outcomes: Adverse effects and the doses at which they occurred Limitations: Only the abstract was read. One author is linked to a research company (ZETA Research Ltd). The authors argue for changing the official limits, which no agency has done. Funding and conflicts: Funding is not stated in the abstract; two authors list an affiliation with ZETA Research Ltd, Trieste. Read: abstract
Schandelmaier 2017 Niacin for primary and secondary prevention of cardiovascular events. Cochrane Database Syst Rev · PMID 28616955 · DOI	Systematic review meta analysis	39195 23 randomised trials in adults with or without cardiovascular disease (median 100% on statins)	Niacin (nicotinic acid) alone or added to other lipid treatment, versus placebo or usual care Nutrient supplement (pharmacological amounts) Median 2 g a day Median treatment 11.5 months (6 months to 6 years) · vs Placebo or usual care	Niacin did not reduce total death (RR 1.05; high-quality evidence), cardiovascular death (RR 1.02; moderate), heart attacks (RR 0.93; moderate) or strokes (RR 0.95; low). People on niacin were more likely to stop because of side effects (RR 2.17; moderate-quality evidence). The authors say benefits for preventing cardiovascular events are unlikely. RR 1.05 total death; RR 2.17 stopping for side effects (Total death 0.97 to 1.12; heart attacks 0.87 to 1.00; stopping for side effects 1.70 to 2.77) Methods, limits and funding Outcomes: Total death, cardiovascular death, heart attacks, strokes, stopping treatment because of side effects Limitations: Trials used very high amounts of nicotinic acid, mostly in people on statins. It says nothing about niacin in food or about deficiency. Funding and conflicts: The authors report no known conflicts of interest. Read: abstract
Tosti 2023 The Role of Nicotinamide as Chemo-Preventive Agent in NMSCs: A Systematic Review and Meta-Analysis. Nutrients · PMID 38201930 · DOI	Systematic review meta analysis	Four studies of oral nicotinamide in people at high risk of non-melanoma skin cancer (immunocompetent and immunosuppressed pooled)	Oral nicotinamide (niacinamide) Nutrient supplement (pharmacological amounts) Varied by study Varied by study · vs Placebo	When the four studies were pooled there was no significant association between nicotinamide and squamous-cell cancer (RR 0.81), basal-cell cancer (RR 0.88) or non-melanoma skin cancer overall (RR 0.82). The authors conclude there is insufficient evidence that oral nicotinamide significantly reduces keratinocyte cancers. Side effects were rare. RR 0.82 for non-melanoma skin cancer (not significant) (95% CI 0.61 to 1.12 (overall); squamous 0.48 to 1.37; basal 0.50 to 1.55) Methods, limits and funding Outcomes: New squamous-cell, basal-cell and non-melanoma skin cancers Limitations: Pools people with normal and suppressed immune systems, which may hide a real effect in one group; only four studies. Funding and conflicts: The authors declare no conflicts of interest. Read: abstract
s-medlineplus-niacin MedlinePlus: Niacin · Source	Health agency n/a			Methods, limits and funding Read: full-text
s-medlineplus-pellagra MedlinePlus: Pellagra · Source	Health agency n/a			Methods, limits and funding Read: full-text
s-nhs-vitamin-b NHS: B vitamins and folic acid · Source	Health agency n/a			Methods, limits and funding Read: full-text
s-ods-niacin NIH Office of Dietary Supplements: Niacin, Fact Sheet for Health Professionals · Source	Health agency n/a			Methods, limits and funding Read: full-text

What we do not know yet

No modern controlled trial of niacin for treating pellagra was found; it rests on clinical experience and agency statements.
The trials on cholesterol, skin cancer and type 1 diabetes used medicine-level amounts; none tested food niacin or multivitamin amounts.
No trial of niacin supplements for energy, mood, memory or skin in people who are not deficient was found.
No source read gave pregnancy or breastfeeding safety data for high-amount niacin.
The LiverTox page could not be read. The American College of Cardiology, American Heart Association and WHO statements were read second-hand through NIH. The live NIH page was blocked, so an archive copy was read.
Nicotinamide creams, kidney disease uses, NMN and nicotinamide riboside were not researched.

How new research is added

New studies are found by a saved PubMed search and placed in a review queue before the page changes.

Lab markers

What changed in blood or saliva tests during trials. A changed number is not the same as feeling or being healthier, and we give no "normal ranges".

Metabolic 3

▲

HDL cholesterol (the "good" cholesterol)

Raised in trials

A blood fat carrier measured on a standard cholesterol test.

High certainty

Results and what it means

Why it was measured

Low HDL is linked with higher heart risk, so it was a target for niacin.

Statistical vs. clinical meaning

HDL rises with nicotinic acid, but in both big trials the rise did not mean fewer heart events.

Safety implication

The rise comes with flushing, higher blood sugar and other effects at these amounts.

Study	Result	People	Product
¹	Median HDL rose from 35 to 42 mg/dL after 2 years of extended-release niacin added to simvastatin.	3414 adults with cardiovascular disease and low HDL	Extended-release niacin 1500 to 2000 mg a day plus simvastatin
⁶	HDL averaged 6 mg/dL higher than placebo.	25,673 adults with vascular disease on statins	2 g extended-release niacin with 40 mg laropiprant daily

^{1 6}

▼

LDL cholesterol (the "bad" cholesterol)

Lowered in trials

The main cholesterol carrier that statins target.

High certainty

Results and what it means

Why it was measured

High LDL is a main treatment target for heart disease.

Statistical vs. clinical meaning

A small extra fall on top of a statin. A 2018 US heart-group report (via ODS) says niacin has only mild LDL-lowering effects.

Safety implication

Same side-effect pattern as above.

Study	Result	People	Product
¹	Median LDL fell from 74 to 62 mg/dL at 2 years.	3414 adults with cardiovascular disease, all on simvastatin	Extended-release niacin 1500 to 2000 mg a day
⁶	LDL averaged 10 mg/dL lower than placebo.	25,673 adults with vascular disease on statins	2 g extended-release niacin with 40 mg laropiprant daily

^{1 6 14}

▼

Triglycerides

Lowered in trials

A blood fat measured on a standard cholesterol test.

High certainty

Results and what it means

Why it was measured

High triglycerides are linked with heart and pancreas problems.

Statistical vs. clinical meaning

ODS reports a 20% to 50% fall across studies and says the US heart groups see niacin as possibly useful in some cases of very high triglycerides.

Safety implication

Needs clinician direction because of the side effects.

Study	Result	People	Product
¹	Median triglycerides fell from 164 to 122 mg/dL at 2 years.	3414 adults with cardiovascular disease, all on simvastatin	Extended-release niacin 1500 to 2000 mg a day

^{1 14}

Other 2

▼

Actinic keratoses (rough, pre-cancerous skin patches)

Lowered in trials

Scaly patches on sun-damaged skin that can turn into squamous-cell skin cancer.

Mixed findings

Results and what it means

Why it was measured

A skin-doctor count used as an early sign of sun damage.

Statistical vs. clinical meaning

Lower in one trial, not in the other.

Safety implication

None noted in the trials.

Study	Result	People	Product
³	Patch counts were 11% lower at 3 months, 14% at 6, 20% at 9 and 13% at 12 months on nicotinamide than on placebo.	386 adults with repeated non-melanoma skin cancers	Nicotinamide 500 mg twice a day for 12 months
²	No significant difference in actinic keratosis counts.	158 organ-transplant recipients	Nicotinamide 500 mg twice a day for 12 months

^{3 2}

▲

New diagnosis of diabetes (a harm signal)

Raised in trials

A first diagnosis of diabetes during a trial.

High certainty

Results and what it means

Why it was measured

High-amount nicotinic acid raises blood sugar, so trials counted new diabetes.

Statistical vs. clinical meaning

A real risk at medicine-level amounts of nicotinic acid, whether or not a statin is also taken.

Safety implication

People with diabetes or at risk need clinician monitoring if prescribed high-amount niacin.

Study	Result	People	Product
⁵	1371 of 26,340 people developed diabetes; risk with niacin was RR 1.34 (1.21 to 1.49), about 1 extra case per 43 people treated for 5 years.	11 randomised trials in people without diabetes	Niacin (nicotinic acid) in pharmacological amounts
⁶	New diabetes diagnoses were 1.3 percentage points higher, and serious diabetes-control problems 3.7 points higher, with niacin-laropiprant than with placebo.	25,673 adults with vascular disease	2 g extended-release niacin with 40 mg laropiprant daily

^{5 6}

Safety

What studies and official sources say about side effects, medicines and who should check first. Each point shows what kind of evidence it comes from.

Main points to know 5

Food niacin is not linked to harm; supplements at higher amounts are the concern. ODS says no adverse effects have been reported from naturally occurring niacin in foods. Problems come from supplements and medicines, and the two main forms act differently: nicotinic acid causes flushing and, at medicine-level amounts, liver and blood-sugar problems; nicotinamide does not flush but can also cause problems at high amounts. Authoritative guidance ¹⁴
Flushing from nicotinic acid. Skin flushing (redness, burning, tingling, itching of the face, arms and chest) is the usual first effect of nicotinic acid supplements. ODS calls it unpleasant rather than toxic, but says it can come with headache, rash, dizziness or a drop in blood pressure. Nicotinamide does not cause flushing. Authoritative guidance ^{14 11}
Liver damage with high amounts over time. ODS says high amounts of nicotinic acid taken over months or years can raise liver enzymes and can cause hepatitis and acute liver failure, and that this is more likely with extended-release forms. The NHS and MedlinePlus also list liver damage. Authoritative guidance ^{14 13 11}
Raised blood sugar and new diabetes. In 11 randomised trials (26,340 people without diabetes), niacin was linked with a higher risk of being diagnosed with diabetes (RR 1.34, 1.21 to 1.49), about one extra case per 43 people treated for 5 years. HPS2-THRIVE found the same pattern. Controlled trial ^{5 6}
Medicine-level niacin added to a statin brought more serious side effects and no heart benefit. In HPS2-THRIVE (25,673 people), extended-release niacin with laropiprant raised serious stomach and bowel, muscle and bone, skin, infection and bleeding events, as well as diabetes problems, with no fall in major vascular events. A Cochrane review found people on niacin were about twice as likely to stop treatment because of side effects (RR 2.17). Controlled trial ^{6 9}

Side effects 7

Effect	How often	Severity and recovery	Evidence
Skin flushing, burning, tingling and itching Nicotinamide does not cause flushing. "Flush-free" inositol hexanicotinate is absorbed about 30% less well on average (ODS).	Not given as a rate in the sources read. ODS says it can start within 30 minutes of a nicotinic acid dose or build over days or weeks of repeat use, and usually eases.	unpleasant; usually not dangerous Described as transient (ODS). MedlinePlus advises avoiding hot drinks and alcohol around the dose to limit flushing.	Authoritative guidance ^{14 11}
Low blood pressure, dizziness and falls ODS lists low blood pressure severe enough to raise the risk of falls at medicine-level nicotinic acid.	Not given.	can be serious in medicine-level use Not described.	Authoritative guidance ¹⁴
Higher blood sugar, insulin resistance and new diabetes Also in HPS2-THRIVE: serious diabetes-control problems +3.7 percentage points.	RR 1.34 for new diabetes across 11 trials; about 1 extra case per 43 people over 5 years.	can be serious Not described.	Controlled trial ^{5 6 14}
Stomach and bowel upset: nausea, heartburn, abdominal pain, diarrhoea, ulcers, bleeding MedlinePlus lists peptic ulcers with too much niacin.	In HPS2-THRIVE serious stomach and bowel events were 1.0 percentage point higher with niacin-laropiprant.	mild to serious Not described.	Controlled trial ^{6 14 11}
Blurred vision and macular oedema (fluid in the central retina) Listed by ODS for medicine-level nicotinic acid.	Not given.	can be serious Not described.	Authoritative guidance ¹⁴
Muscle and bone problems, infections, bleeding, skin rashes The product also contained laropiprant, so not every effect can be pinned on niacin alone.	In HPS2-THRIVE: muscle and bone events +0.7, skin +0.3, infection +1.4, bleeding +0.7 percentage points.	serious adverse events Not described.	Controlled trial ⁶
Nicotinamide at high amounts: nausea, vomiting, signs of liver stress; in dialysis patients, diarrhoea and low platelets The NHS says there is not enough evidence on the effects of high daily amounts of nicotinamide. ONTRAC and ONTRANS saw no noteworthy side-effect differences.	Not given.	mild to serious Not described.	Authoritative guidance ¹⁴

Liver

ODS says high amounts of nicotinic acid taken for months or years can raise liver enzymes and cause fatigue, nausea, loss of appetite, hepatitis and acute liver failure, and that extended-release forms carry more risk. The US heart groups advise liver blood tests before starting medicine-level nicotinic acid, while the dose is raised, and every 6 months, and advise stopping if liver enzymes reach more than two or three times the upper limit of normal. The LiverTox page on niacin could not be read, so no LiverTox statement is used. ^{14 13 11}

How often. No frequency was found in the sources read.

Monitoring. ODS reports that the American College of Cardiology and American Heart Association advise liver enzymes, fasting glucose or HbA1c, and uric acid checks before and during medicine-level nicotinic acid. Food-level niacin does not need this.

This is a safety connection. It is not evidence that Vitamin B3 (niacin) supports liver health.

Medicines and supplements 5

With	Why it matters	Importance	Evidence	What to do
Statins (for example simvastatin) prescription	Not a drug-level interaction; the question is whether adding niacin helps or harms.	Adding extended-release niacin to a statin gave no extra heart benefit (AIM-HIGH, HPS2-THRIVE) and more serious side effects, including muscle and bone events, in THRIVE. ODS reports a 2018 US heart-group statement that niacin is not recommended as an add-on to a statin.	Controlled trial High certainty ^{1 6 14}	If you take a statin, ask your prescriber before adding niacin supplements.
Diabetes medicines (including insulin) prescription	High amounts of nicotinic acid can raise blood sugar by worsening insulin resistance and raising the liver's sugar output (ODS).	ODS says people on diabetes medicines who take high-amount nicotinic acid should have their blood sugar monitored because doses may need adjusting, and says effects on blood sugar are most likely at 1.5 g a day or more.	Authoritative guidance Moderate certainty ^{14 5}	Ask your prescriber or pharmacist before taking high-amount niacin.
Isoniazid and pyrazinamide (tuberculosis medicines) prescription	They resemble niacin and block the steps that make niacin from tryptophan; isoniazid can also interfere with turning niacin into NAD (ODS).	Pellagra can occur in people treated with isoniazid; ODS says it can be prevented with more niacin. This is a case where the medicine lowers niacin, rather than niacin harming the medicine.	Authoritative guidance Moderate certainty ^{14 12}	People on tuberculosis treatment should follow their clinician's advice on niacin and other B vitamins.
Alcohol other	MedlinePlus advises avoiding alcohol and hot drinks with niacin to limit flushing; alcohol use disorder is also a cause of niacin deficiency.	Alcohol can add to flushing; heavy long-term alcohol use is a recognised cause of pellagra (MedlinePlus). Alcohol and high-amount niacin both stress the liver, but no source read tested the combination.	Authoritative guidance Low certainty ^{11 12}	Avoid alcohol around flush-causing niacin; ask a clinician about alcohol use and liver health.
Blood pressure medicines prescription	Niacin flushing widens small blood vessels and ODS lists low blood pressure with high amounts.	No source read states a tested interaction with blood pressure medicines. It is a theoretical addition to any blood-pressure-lowering effect.	Pharmacological theory Not enough evidence ¹⁴	Ask your prescriber or pharmacist if you take blood pressure medicines.

Who should check first 6

Situation	Advice	Evidence
Rising liver enzymes, or unexplained abdominal pain or stomach symptoms, while taking high-amount nicotinic acid	ODS reports the US heart groups advise not to start, or to stop, medicine-level nicotinic acid in these situations. Ask the prescriber.	Authoritative guidance ¹⁴
Diabetes, persistent high blood sugar, or acute gout	The same US heart-group advice says to stop medicine-level nicotinic acid with persistent high blood sugar or acute gout. Ask the prescriber.	Authoritative guidance ¹⁴
New irregular heartbeat (atrial fibrillation), unexplained weight loss, or persistent severe skin reactions on high-amount nicotinic acid	ODS reports the same advice to stop and get medical help.	Authoritative guidance ¹⁴
Pregnancy and breastfeeding	ODS gives higher recommended intakes in pregnancy (18 mg NE) and breastfeeding (17 mg NE), and the same upper limits as other adults of the same age. We found no source describing risks of high-amount niacin in pregnancy or breastfeeding, so a gap is not an all-clear. Ask your midwife, doctor or pharmacist before taking niacin supplements.	Authoritative guidance ¹⁴
Children and teenagers	ODS sets upper limits for supplement niacin of 10 mg (ages 1 to 3), 15 mg (4 to 8), 20 mg (9 to 13) and 30 mg (14 to 18), and says breast milk, formula and food should be the only niacin sources for babies. Ask a paediatrician.	Authoritative guidance ¹⁴
People on dialysis	In small studies in dialysis patients, nicotinamide caused diarrhoea and low platelets (ODS). Ask a kidney doctor.	Authoritative guidance ¹⁴

Overdose, product quality and regulators

Summary. Niacin from food has no reported toxicity (ODS). Supplements can cause flushing at amounts well above food levels, and serious harm at medicine-level amounts. The official upper limit is based on flushing.

Animal. Not reviewed.

Human doses studied. Medicine-level amounts in the trials are listed in the studies table. A 2017 review of 47 articles (11,741 people) found major adverse effects in healthy people taking nicotinic acid alone at amounts below 1000 mg a day, and argued the current limits could be reconsidered.

High dose or long term signals. Liver injury with months or years of high-amount nicotinic acid; higher diabetes risk; falls from low blood pressure; vision changes (ODS, trials).

Overdose response. Not found.

Genotoxicity. Not researched.

No study of contamination or label accuracy in niacin supplements was read.

"Flush-free" niacin. ODS says inositol hexanicotinate supplements are often labelled flush-free. Absorption from them varies widely and is on average 30% lower than from nicotinic acid or nicotinamide, which are almost completely absorbed. ¹⁴

Strong single-ingredient products. ODS says some niacin-only supplements contain 500 mg or more per serving, much higher than the RDA. Check the label for the form (nicotinic acid or nicotinamide) and the amount per serving. ¹⁴

NMN. ODS says the US FDA ruled in November 2022 that NMN may not be legally sold as a dietary supplement. NMN and nicotinamide riboside are not sold as niacin sources. We did not read the FDA's own statement. ¹⁴

Body	Action	Date
NIH Office of Dietary Supplements (US) (United States)	Recommended Dietary Allowance for niacin is 16 mg NE a day for men and 14 mg NE for women aged 14 and over (18 mg NE in pregnancy, 17 mg NE when breastfeeding). The tolerable upper intake level for supplemental niacin is 35 mg a day for adults (30 mg for ages 14 to 18; 10, 15 and 20 mg for ages 1 to 3, 4 to 8 and 9 to 13; none set for infants). The limit is based on flushing and does not apply to people taking niacin under medical supervision. source	2022-11-18
MedlinePlus (US National Library of Medicine) (United States)	Too much niacin can cause raised blood sugar, liver damage, peptic ulcers and skin rashes. Medicine-level niacin can cause flushing. Large amounts can modestly raise HDL and lower triglycerides; talk to a provider before starting supplements. Niacin deficiency causes pellagra. source	2025-01-21
MedlinePlus: Pellagra (United States)	Pellagra is caused by too little niacin or tryptophan, or by poor absorption; it is treated with niacin supplements directed by a provider. Untreated it can lead to nerve damage and death. source	2024-10-27
NHS (UK) (United Kingdom)	About 16.5 mg niacin a day for men and 13.2 mg for women. Supplements of 17 mg or less of nicotinic acid, or 500 mg or less of nicotinamide, a day are unlikely to cause harm. High nicotinic acid supplements can cause skin flushes and, taken long term, liver damage. There is not enough evidence on high daily nicotinamide. source	2020-08-03

When to get medical help

Fatigue, nausea, loss of appetite or abdominal pain after weeks to months of high-amount niacin: these can be signs of liver trouble (ODS). Stop and call your clinician.
Fainting, severe dizziness, or a new irregular heartbeat while taking high-amount niacin.
Blurred or worsening vision.
Persistent diarrhoea, a scaly rash on sun-exposed skin, or new confusion: these can be signs of pellagra and need medical care (MedlinePlus).

Stop using the product and contact a clinician or emergency service. In the US, Poison Control is 1-800-222-1222.

General information only, not medical advice. Ask a clinician or pharmacist before use, especially with medicines, in pregnancy or with a health condition. See the Natural Remedy Safety guide.

Frequently asked questions

What is vitamin B3?

Vitamin B3 is niacin, a B vitamin that helps the body release energy from food and keeps skin, nerves and the digestive system working. It comes as nicotinic acid and nicotinamide. Both are in food.

^{11 13}

Are niacin, niacinamide, nicotinamide and nicotinic acid the same?

Niacin is the umbrella name. Nicotinic acid and nicotinamide (also called niacinamide) are its two forms. Only nicotinic acid causes flushing and changes blood fats at high amounts. Nicotinamide does not flush and was the form used in the skin-cancer trials.

^{14 13}

Which foods have niacin?

Meat, poultry, fish, peanuts, brown rice and whole grains, and enriched breads and cereals. A 3-ounce portion of beef liver has 14.9 mg and of chicken breast 10.3 mg, while a cup of plain low-fat yogurt has 0.3 mg, according to NIH. The body also makes some niacin from tryptophan.

^{14 11}

What happens if you do not get enough niacin?

A severe lack causes pellagra, with diarrhoea, scaly sores on sun-exposed skin and confusion, and it can be fatal if untreated. It is rare in rich countries and is seen with heavy alcohol use, bowel disease, weight-loss surgery, some medicines and very poor diets. See a clinician for these symptoms.

^{12 14 7}

Does niacin lower cholesterol?

At medicine-level amounts, nicotinic acid raised HDL and lowered LDL and triglycerides (AIM-HIGH: HDL 35 to 42, LDL 74 to 62, triglycerides 164 to 122 mg/dL). The effect on LDL is small next to a statin. Nicotinamide does not do this. Talk to a prescriber rather than self-treating.

^{1 6 14}

Does niacin prevent heart attacks?

No. A Cochrane review of 23 trials (39,195 people) found no reduction in deaths (RR 1.05), heart attacks (RR 0.93) or strokes (RR 0.95), and more people stopped because of side effects (RR 2.17). Two very large trials agreed.

^{9 1 6}

Why does niacin make my skin flush?

Nicotinic acid widens small blood vessels under the skin, causing redness, burning, tingling and itching of the face, neck, arms and chest. ODS calls it unpleasant rather than toxic. Nicotinamide does not cause it. MedlinePlus advises avoiding hot drinks and alcohol with niacin to limit flushing.

^{14 11}

Can nicotinamide prevent skin cancer?

Results are mixed. In 386 people with repeated skin cancers, it gave 23% fewer new non-melanoma skin cancers over 12 months, but the benefit stopped when they stopped. It did nothing in 158 transplant recipients, and pooled results were not significant. It is not a substitute for sun protection and skin checks.

^{3 2 10}

Can niacin harm the liver or raise blood sugar?

High-amount nicotinic acid taken for months or years can raise liver enzymes and cause hepatitis or liver failure, more often with extended-release forms (ODS). Across 11 trials it raised the risk of a new diabetes diagnosis (RR 1.34). These are medicine-level amounts and need a clinician's monitoring.

^{14 5 6}

Does niacin interact with medicines?

Yes in some cases. Isoniazid and pyrazinamide (tuberculosis medicines) can cause pellagra. Diabetes medicines may need adjusting if you take high-amount nicotinic acid. Adding niacin to a statin gave no extra benefit and more serious side effects. Ask your pharmacist.

^{14 1 6}

Is niacin safe in pregnancy, breastfeeding and for children?

The recommended intakes are higher in pregnancy (18 mg NE) and breastfeeding (17 mg NE). We found no source describing risks of high-amount niacin in pregnancy or breastfeeding, which is a gap and not an all-clear. For babies, NIH says breast milk, formula and food should be the only sources. Ask a doctor or pharmacist.

¹⁴

Will niacin give me more energy?

Niacin helps the body release energy from food, but we found no trial showing that extra niacin supplements add energy in people who already get enough. Fatigue has many causes, so see a clinician if it persists.

^{11 13 14}

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Editorial transparency

Written by: AlternativeMed editorial team. Research compiled with AI assistance, then checked against the sources listed.
Medical review: None. This page has not been reviewed by a physician or pharmacist.
First published: 2026-10-26
Last substantive update: 2026-10-26
How we research: We started from our existing vitamin B3 summary, then read NIH Office of Dietary Supplements (via an archive copy), MedlinePlus and NHS pages, and re-read PubMed abstracts for the trials and reviews. Only abstracts were read for studies. Items we could not verify are flagged in the research gaps.
How we rate evidence: See "How we rate evidence" in the Evidence tab.
Independence: No product is promoted on this page. No affiliate links are shown. Two of the big heart trials were funded in part by makers of niacin medicines (Abbott, Merck); this is stated where they are used.

Sources 14

Each source was opened and checked. Where we read only the abstract, it says so. The small numbers in the text point here.

AIM-HIGH Investigators; Boden WE, Probstfield JL, Anderson T and others. Niacin in patients with low HDL cholesterol levels receiving intensive statin therapy.. N Engl J Med. 2011. PMID 22085343. DOI 10.1056/NEJMoa1107579. (abstract)
Allen NC, Martin AJ, Snaidr VA and others. Nicotinamide for Skin-Cancer Chemoprevention in Transplant Recipients.. N Engl J Med. 2023. PMID 36856616. DOI 10.1056/NEJMoa2203086. (abstract)
Chen AC, Martin AJ, Choy B and others. A Phase 3 Randomized Trial of Nicotinamide for Skin-Cancer Chemoprevention.. N Engl J Med. 2015. PMID 26488693. DOI 10.1056/NEJMoa1506197. (abstract)
Gale EA, Bingley PJ, Emmett CL, Collier T; ENDIT Group. European Nicotinamide Diabetes Intervention Trial (ENDIT): a randomised controlled trial of intervention before the onset of type 1 diabetes.. Lancet. 2004. PMID 15043959. DOI 10.1016/S0140-6736(04)15786-3. (abstract)
Goldie C, Taylor AJ, Nguyen P and others. Niacin therapy and the risk of new-onset diabetes: a meta-analysis of randomised controlled trials.. Heart. 2016. PMID 26370223. DOI 10.1136/heartjnl-2015-308055. (abstract)
HPS2-THRIVE Collaborative Group; Landray MJ, Haynes R, Hopewell JC and others. Effects of extended-release niacin with laropiprant in high-risk patients.. N Engl J Med. 2014. PMID 25014686. DOI 10.1056/NEJMoa1300955. (abstract)
Hegyi J, Schwartz RA, Hegyi V. Pellagra: dermatitis, dementia, and diarrhea.. Int J Dermatol. 2004. PMID 14693013. DOI 10.1111/j.1365-4632.2004.01959.x. (abstract)
Minto C, Vecchio MG, Lamprecht M, Gregori D. Definition of a tolerable upper intake level of niacin: a systematic review and meta-analysis of the dose-dependent effects of nicotinamide and nicotinic acid supplementation.. Nutr Rev. 2017. PMID 28541582. DOI 10.1093/nutrit/nux011. (abstract)
Schandelmaier S, Briel M, Saccilotto R and others. Niacin for primary and secondary prevention of cardiovascular events.. Cochrane Database Syst Rev. 2017. PMID 28616955. DOI 10.1002/14651858.CD009744.pub2. (abstract)
Tosti G, Pepe F, Gnagnarella P and others. The Role of Nicotinamide as Chemo-Preventive Agent in NMSCs: A Systematic Review and Meta-Analysis.. Nutrients. 2023. PMID 38201930. DOI 10.3390/nu16010100. (abstract)
. MedlinePlus: Niacin. . . (full-text)
. MedlinePlus: Pellagra. . . (full-text)
. NHS: B vitamins and folic acid. . . (full-text)
. NIH Office of Dietary Supplements: Niacin, Fact Sheet for Health Professionals. . . (full-text)

Where to buy

Check the label first. Whatever you buy, look for these:

The amount of the active ingredient per serving, not just the front-label claim
A third-party testing mark (USP, NSF or ConsumerLab)
Other ingredients and allergens
Ask a pharmacist about interactions with your medicines

Talk to a pharmacist or doctor before you start any supplement, especially if you take medicines. See the Safety tab for interactions.

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Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.