Nutrients & Compounds in Foods
A plain index to the compounds in functional foods, such as beta-glucan, polyphenols, nitrate, omega-3, plant sterols and sulforaphane, and what each source found for food versus supplement.
Content last updated . This page has not been medically reviewed.
Safety first. Natural products can cause side effects and interact with medicines. Read functional food safety before you use anything on this page.
News about food often credits one compound: "the beta-glucan in oats" or "the nitrate in beets". This page is the index to those compounds. For each one it says which foods contain it, what the best sources found, and where food and supplement studies must be kept apart. A result for a compound, an extract or a supplement does not automatically carry over to the whole food, and the reverse is also true. This page gives information only, not personal advice.
How to read the table
The "evidence" column uses the labels used across this library: established, promising but limited, mixed, insufficient evidence, observational only and preclinical. Most food findings come from cohort studies or short trials that measure a marker such as LDL cholesterol or blood pressure, not heart attacks or strokes. See observational studies versus trials for how to weigh that.
The compounds at a glance
| Compound | Foods | What the sources show | Evidence |
|---|---|---|---|
| Beta-glucan (soluble fiber) | Oats, barley | A meta-analysis of 28 trials found that 3 g or more a day of oat beta-glucan lowered LDL cholesterol by 0.25 mmol/L. [1] The US FDA allows a heart-disease health claim for it from whole oats or barley. [2] Details | Established for LDL |
| Fiber for constipation | Many plant foods, but the trials studied supplements | A review of 16 trials of fiber supplements found improved constipation, with more flatulence. [3] This is not a food trial. See fiber amounts and side effects. | Supplement evidence |
| Resistant starch | Cooked-and-cooled starches, legumes, some grains | In people with type 2 diabetes or prediabetes, types 1 and 2 lowered after-meal blood glucose in a meta-analysis of randomized trials. [4] A separate review of supplements found small cholesterol changes. [5] See resistant starch foods. | Promising but limited |
| Polyphenols and flavonoids | Berries, cocoa, tea, citrus, olive oil | Mixed: a trial of blueberry powder in older adults found vascular benefits, while a hesperidin review found none for lipids or blood pressure. [6][7] Details | Mixed |
| Lycopene | Tomatoes | A pooled analysis found a weak link between tomato intake and lower prostate cancer risk, but cohort studies alone showed no link. [8] See tomatoes. | Observational only, mixed |
| Lutein | Avocado, leafy greens | In a six-month trial funded by an avocado board, daily avocado raised macular pigment density versus a potato or chickpeas. [9] See avocado. | Insufficient evidence (one small trial) |
| Omega-3 fatty acids | Oily fish (EPA, DHA); walnuts, flax, chia (ALA) | Fish studies are observational. [10] Details | Observational for fish |
| Plant sterols and stanols | Fortified spreads and some other fortified foods | A meta-analysis of 124 studies found 0.6 to 3.3 g a day lowered LDL cholesterol by 6 to 12 percent on average. [11] Details | Established for LDL |
| Soy protein and isoflavones | Soy foods | Soy protein (median 25 g a day) lowered LDL by 4.76 mg/dL in a meta-analysis; soy isoflavones had mixed effects on menopause symptoms in a small-sample review. [12][13] See soy foods. | Small LDL effect; mixed for symptoms |
| Dietary nitrate | Beets, leafy greens | Beet juice lowered clinic systolic blood pressure in adults with hypertension, with low certainty; another review found no effect in hypertensive adults. [14][15] Details | Mixed, low certainty |
| Glucosinolates and sulforaphane | Broccoli and other crucifers | Mostly lab and small-trial findings about how the compound forms and is absorbed. [16][17] Details | Preclinical and early human |
What this does not mean
- A compound that works in a trial may not work the same way inside a whole food, and a supplement made from it can carry different risks. A large cocoa-extract trial, for example, studied an extract and not chocolate. [18]
- Antioxidant vitamin and mineral supplements are a separate topic from antioxidant-rich foods; see antioxidants explained.
- Nutrition values for a specific food are not given here. We did not read a food-composition database for this page, so check the Nutrition Facts label or a national database.
Frequently asked questions
Is fiber from food the same as a fiber supplement?
We did not find a source that compares them directly. The constipation review we read studied supplements, not foods. [3]
Does a compound in a food explain the food's effect?
Not necessarily. Oat beta-glucan has trial evidence for LDL cholesterol. [1] For many other compounds, the trials used extracts or supplements rather than the food, so the result may not apply to the food.
Which compound has the strongest evidence?
For lowering LDL cholesterol, oat beta-glucan and plant sterols or stanols each have meta-analyses of randomized trials behind them. [1][11] Both findings concern a blood marker, not heart attacks.
Are compounds in food safer than in supplements?
Sources we read do not make a general comparison. Antioxidant vitamin supplements, for example, were examined in a large Cochrane review that reported higher mortality for beta-carotene and vitamin E in low-risk-of-bias trials. [19] That review concerned supplements, not foods.
Where can I check a single food?
Use the functional foods A to Z directory, which links each food page with its evidence label.
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
Safety and who should ask a professional
Food allergy, medicine interactions (for example vitamin K foods with warfarin, or grapefruit) and pregnancy guidance are covered on the safety page. If you take regular medicines or have a kidney, liver or bleeding condition, ask a pharmacist or clinician before changing your diet in a big way. The general idea of how interactions are classed is explained in How Interactions Work.
References
- Cholesterol-lowering effects of oat β-glucan: a meta-analysis of randomized controlled trials. Am J Clin Nutr 2014. PMID 25411276. Read 2026-10-23.
- 21 CFR 101.81, Health claims: soluble fiber from certain foods and risk of coronary heart disease. US Electronic Code of Federal Regulations. Read 2026-10-23.
- The Effect of Fiber Supplementation on Chronic Constipation in Adults: An Updated Systematic Review and Meta-Analysis of Randomized Controlled Trials. Am J Clin Nutr 2022. PMID 35816465. Read 2026-10-23.
- A comparison of the effects of resistant starch types on glycemic response in individuals with type 2 diabetes and prediabetes: a systematic review and meta-analysis. Front Nutr 2023. PMID 37051127. Read 2026-10-23.
- Meta-analysis indicates that resistant starch lowers serum total cholesterol and low-density cholesterol. Nutr Res 2018. PMID 29914662. Read 2026-10-23.
- Wild blueberry (poly)phenols can improve vascular function and cognitive performance in healthy older individuals: a double-blind randomized controlled trial. Am J Clin Nutr 2023. PMID 36972800. Read 2026-10-23.
- Hesperidin, a major flavonoid in orange juice, might not affect lipid profile and blood pressure: a systematic review and meta-analysis of randomized controlled clinical trials. Phytother Res 2019. PMID 30632207. Read 2026-10-23.
- Tomato consumption and prostate cancer risk: a systematic review and meta-analysis. Sci Rep 2016. PMID 27841367. Read 2026-10-23.
- Avocado Consumption Increases Macular Pigment Density in Older Adults: A Randomized, Controlled Trial. Nutrients 2017. PMID 28832514. Read 2026-10-23.
- Fish Consumption and Cardiovascular Health: A Systematic Review. Am J Med 2021. PMID 33444594. Read 2026-10-23.
- LDL-cholesterol-lowering effect of plant sterols and stanols across different dose ranges: a meta-analysis of randomised controlled studies. Br J Nutr 2014. PMID 24780090. Read 2026-10-23.
- A Meta-Analysis of 46 Studies Identified by the FDA Demonstrates that Soy Protein Decreases Circulating LDL and Total Cholesterol Concentrations in Adults. J Nutr 2019. PMID 31006811. Read 2026-10-23.
- Effects of soy isoflavones on menopausal symptoms in perimenopausal women: a systematic review and meta-analysis. PeerJ 2025. PMID 40718787. Read 2026-10-23.
- Effects of beetroot juice on blood pressure in hypertension according to European Society of Hypertension Guidelines: a systematic review and meta-analysis. Nutr Metab Cardiovasc Dis 2024. PMID 39069465. Read 2026-10-23.
- Regulatory effect of dietary nitrate on blood pressure: a meta-analysis of randomized controlled trials. Food Funct 2023. PMID 36740972. Read 2026-10-23.
- Approaches for enhancing the stability and formation of sulforaphane. Food Chem 2021. PMID 33601652. Read 2026-10-23.
- Absorption and metabolism of isothiocyanates formed from broccoli glucosinolates: effects of BMI and daily consumption in a randomised clinical trial. Br J Nutr 2018. PMID 30499426. Read 2026-10-23.
- Cocoa flavanol supplementation and prevention of cardiovascular disease: a novel analysis of the COSMOS randomized trial using "win ratio". Eur J Epidemiol 2026. PMID 41849087. Read 2026-10-23.
- Antioxidant supplements for prevention of mortality in healthy participants and patients with various diseases. Cochrane Database Syst Rev 2012. PMID 22419320. Read 2026-10-23.