Flaxseed Oil: Nutrients, What Research Shows and Safety
Flaxseed oil as a food: its very high plant omega-3 (ALA) content by USDA values, what trials and cohorts found, conversion to fish omega-3s, and cautions.
Content last updated . This page has not been medically reviewed.
Flaxseed oil, also called linseed oil, is pressed from the seeds of the flax plant, Linum usitatissimum. It is the richest common food source of alpha-linolenic acid (ALA), a plant omega-3 fat. [1] [8] People take it as a bottled oil, over cold foods, or in capsules. This page is about the oil. It keeps the oil apart from ground flaxseed (a different food, with fiber) and from fish oil.
Read this first
- Very high in ALA. USDA lists 53.4 g of ALA in 100 g, or about 7.3 g in a tablespoon. [1] The US Adequate Intake for ALA is 1.6 g a day for men and 1.1 g for women. [8] These are official reference figures, not a target for the oil.
- Do not expect it to replace fish oil. The body turns only some ALA into the long-chain omega-3s (EPA and DHA) in fish; supplementing ALA has little effect on blood DHA. [8] [2]
- Heart evidence is modest. A Cochrane review of long trials found increasing ALA probably makes little or no difference to deaths and may slightly lower cardiovascular events. [9]
- Medicines: NCCIH says flaxseed oil could in theory interact with blood thinners and antiplatelet drugs; talk to a health care provider if you take medicine. [3]
- Allergic reactions to flaxseed and its oil have been reported. For trouble breathing or swelling of the face or throat, call 911 (or your local emergency number). [8]
- It spoils easily. Polyunsaturated oils go rancid more easily than saturated fats. [8] Follow the storage line on the bottle.
What is in it (USDA values)
The values below are for cold-pressed flaxseed oil (USDA FoodData Central item 167702, SR Legacy). [1] The serving column is the USDA household portion of 1 tablespoon, 13.6 g. [1]
| Nutrient | Per 100 g | Per 1 tablespoon (13.6 g) | % Daily Value per serving |
|---|---|---|---|
| Energy | 884 kcal | 120 kcal | not set |
| Total fat | 99.98 g | 13.6 g | 17% |
| Saturated fat | 8.98 g | 1.22 g | 6% |
| Monounsaturated fat | 18.44 g | 2.51 g | no DV |
| Polyunsaturated fat | 67.85 g | 9.23 g | no DV |
| Alpha-linolenic acid (ALA, omega-3) | 53.37 g | 7.26 g | no DV |
| Linoleic acid (omega-6) | 14.25 g | 1.94 g | no DV |
| Vitamin E (alpha-tocopherol) | 0.47 mg | 0.06 mg | 0% |
| Vitamin K | 9.3 mcg | 1.3 mcg | 1% |
| Total trans fat | 0.094 g | 0.013 g | no DV |
% Daily Value uses the FDA 2016 Daily Values; the serving figures are the 100 g values multiplied by 0.136. The Linus Pauling Institute gives 7.3 g ALA per tablespoon, which matches the USDA figure. [8] USDA also lists a vitamin D figure for several oils; we could not confirm it from a second source, so we do not show it and do not treat oils as a vitamin D source. [1]
Plant compounds: we did not read a source that measured lignans or other compounds in the oil, so we name none. Ground flaxseed has its own page, and its results do not transfer to the oil. See flaxseed.
What research says
| Health goal | What the sources found | Strength of evidence | What was studied |
|---|---|---|---|
| Heart and circulation events | The Cochrane review (86 trials, 162,796 people) found increasing ALA probably makes little or no difference to all-cause or cardiovascular death, and may slightly lower cardiovascular events (relative risk 0.95, interval 0.83 to 1.07) and probably lowers arrhythmia (relative risk 0.73). [9] | Promising but limited | ALA from foods or supplements in trials lasting at least 12 months |
| Blood pressure | A review of 17 trials (14 olive oil, 3 flaxseed oil) found no significant effect on blood pressure or inflammation markers. [4] | No good evidence of benefit (few flaxseed oil trials) | Healthy adults and adults at risk of high blood pressure |
| Triglycerides and CRP | Pooled trials in people on hemodialysis found lower triglycerides and C-reactive protein (CRP) with flaxseed oil, but results varied hugely between trials. [5] | Mixed (a special patient group) | Flaxseed oil in hemodialysis patients |
| Plant ALA, adults with overweight or obesity | Pooled trials of plant ALA found lower CRP, TNF, triglycerides and systolic blood pressure, and slightly higher LDL cholesterol (1.32 mg/dL); the effect was clearer at 3 g a day or more from flaxseed and flaxseed oil. [6] | Promising but limited | 19 trials, 1,183 adults; ALA from foods or supplements |
| Inflammation markers in general | A pooled analysis of 25 ALA trials found no effect on TNF, IL-6 or CRP, and CRP may rise in healthy people. [7] | Mixed | Adults, ALA from various sources |
| Long-chain omega-3 status | Studies in healthy adults found ALA raises blood EPA and DPA but has little effect on DHA. [2] | Established for this blood effect | Healthy adults on Western diets |
| Mortality and cancer (cohorts) | Higher ALA intake was linked to lower all-cause (relative risk 0.90) and cardiovascular death (0.92), and to slightly higher cancer death (1.06). [10] | Mixed (observational) | 41 cohort studies, about 1.2 million people |
| Prostate cancer | A meta-analysis found dietary ALA was not significantly linked to prostate cancer risk (relative risk 1.08, interval 0.90 to 1.29), with large differences between studies. [11] | Mixed (observational) | Case-control and cohort studies |
| Weight loss | NCCIH says flaxseed oil supplements do not seem to help weight loss. [3] | No good evidence of benefit | Supplement trials |
Eaten as food vs taken as capsules. Most trials above gave the oil as a supplement, often in people with a health condition. Using the oil in food is not the same thing. We did not read a source separating the two. The Cochrane review also included trials that raised ALA through foods or advice. [9]
How much is a normal serving
The USDA household portion is 1 tablespoon (13.6 g), about 120 kcal and 7.3 g ALA. [1] This is information, not a prescription. The Institute of Medicine's Adequate Intakes for ALA are 1.6 g a day (men) and 1.1 g (women); no upper limit has been set for omega-3 fats. [8] NCCIH says limited amounts of flaxseed oil may be safe for up to 6 months and higher amounts may cause bloating, fullness and diarrhea. [3] The 2020 to 2025 US Dietary Guidelines count oils within a pattern of 27 g a day at 2,000 calories and name canola, corn, olive, peanut, safflower, soybean and sunflower oils; flaxseed oil is not on that list. [12] NHS names flaxseed (linseed) oil as an omega-3 source for vegetarians. [13]
Safety, allergy and medicines
- Medicine interactions: NCCIH says there are theoretical reasons flaxseed oil could interact with anticoagulant or antiplatelet drugs. [3] The Linus Pauling Institute adds that high doses of flaxseed oil and fish oil may inhibit platelet aggregation, so use them cautiously with anticoagulants. [8] Talk to a pharmacist or clinician, including before surgery. See foods and medicine interactions.
- Digestive effects: high doses may cause loose stools or diarrhea. [8] [3]
- Allergy: reactions to flaxseed and the oil, including anaphylaxis, have been reported. [8] See food allergy basics.
- Pregnancy and breastfeeding: NCCIH says little is known about whether flaxseed oil is safe in pregnancy or breastfeeding. [3] See foods in pregnancy.
- Cancer: the cohort data on ALA and cancer death point slightly upward, and the prostate meta-analysis was inconclusive. [10] [11] These are associations, not proof. Men with prostate concerns can ask their clinician.
- Heating: in a simulated-kitchen deep-frying test, aldehyde output rose with the share of ALA in the oil; flaxseed oil was not tested. [14] We give no smoke-point number because we did not read a source for one. See smoke points and cooking with oil.
- Calories: 120 kcal a tablespoon. [1]
- Kidney disease and diabetes: trials exist in hemodialysis patients and in people with metabolic problems, but they do not make the oil a treatment. [5] Ask your clinician.
- Children: we did not read child-specific advice for the oil.
Choosing, storing and food safety
- Rancidity: polyunsaturated oils oxidize more easily than saturated fats, and vitamin E helps protect them. [8] USDA lists only 0.47 mg of vitamin E per 100 g in this oil. [1] We read no official storage rule, so follow the bottle label (many say to keep it cold and away from light).
- Smell and taste: if it smells sharp or bitter or unpleasant, we suggest not using it; this is common sense, not an official rule.
- Seed vs oil: the oil does not contain the fiber of the seed. See flaxseed.
Related pages
Health connections for Flaxseed Oil
What research links to eating or drinking this food, and how strong the evidence is. Many studies are observational or use juice, powder, oil or extracts rather than the food as eaten; each card says which.
Plant omega-3 (ALA) intake from flaxseed oil
Established roleUSDA lists 53.4 g of ALA in 100 g (about 7.3 g in a tablespoon), the richest common food source. The US Adequate Intake is 1.6 g a day for men and 1.1 g for women.
Supplements: Dietary role only; no upper limit has been set for omega-3 fats.
Conversion of ALA to EPA and DHA
Clinically supportedStudies in healthy adults found ALA raises blood EPA and DPA but has little effect on DHA. Fish oil raises DHA directly.
Supplements: Defined outcome only: a blood level effect, not a disease outcome.
ALA and heart disease events (Cochrane)
Preliminary or mixedA Cochrane review of 86 trials found increasing ALA probably makes little or no difference to deaths and may slightly lower cardiovascular events (relative risk 0.95) and arrhythmia (0.73).
Supplements: Small, uncertain effect.
Plant ALA, blood fats and inflammation in overweight adults
Preliminary or mixedPooled trials of plant ALA in overweight or obese adults found lower CRP, TNF, triglycerides and systolic blood pressure and slightly higher LDL (1.32 mg/dL); the effect was clearer at 3 g a day or more from flaxseed and flaxseed oil.
Supplements: Mixed results across trials and markers.
Flaxseed oil in hemodialysis patients
Preliminary or mixedPooled trials in people on hemodialysis found lower triglycerides and CRP, with very large differences between trials.
Supplements: Does not apply to healthy people.
Flaxseed oil and blood pressure
Not enough evidenceA review of 17 trials (3 of flaxseed oil) found no significant effect on blood pressure or inflammation markers.
Supplements: No good evidence of benefit.
ALA intake, cancer and mortality (cohorts)
Preliminary or mixedA meta-analysis of 41 cohort studies linked higher ALA intake to lower all-cause (relative risk 0.90) and cardiovascular death (0.92) but slightly higher cancer death (1.06). A prostate cancer meta-analysis found ALA intake not significantly linked (1.08, wide uncertainty).
Supplements: Observational only.
Rancidity and heating
Lab or animal research onlyPolyunsaturated oils oxidize more easily than saturated fats; in a kitchen-simulation test of frying oils, aldehyde output rose with the ALA share of the oil (flaxseed oil not tested).
Supplements: No sourced smoke point or storage rule was read; follow the label.
Connected topics
Open a group to see how each topic connects and how strong the evidence is.
Health goals (1)
- Heart HealthPreliminary or mixed
Cochrane found a possible small drop in cardiovascular events with more ALA; deaths unchanged.
Body systems (3)
- Cardiovascular SystemPreliminary or mixed
Same as heart and circulation.
- Digestive SystemDocumented risk
High doses may cause loose stools or diarrhea.
- Heart & CirculationPreliminary or mixed
Possible small effects on events and risk markers.
Body parts (1)
- HeartPreliminary or mixed
Small possible benefit for events; not specific to the oil.
Functional actions (1)
- Cardiovascular SupportPreliminary or mixed
Cochrane: ALA may slightly lower cardiovascular events and probably arrhythmia.
Root causes (1)
- Medication Side EffectsDocumented risk
Theoretical interaction with anticoagulant and antiplatelet drugs.
Habits (1)
- Balanced NutritionPreliminary or mixed
NHS names flaxseed oil as an omega-3 option for vegetarians.
Biomarkers (2)
- LDL CholesterolPreliminary or mixed
Slightly higher LDL (1.32 mg/dL) in the overweight-adult analysis.
- TriglyceridesPreliminary or mixed
Lower triglycerides in pooled trials of plant ALA and in hemodialysis patients.
Conditions & symptoms (3)
- Coronary Heart DiseasePreliminary or mixed
Cochrane: more ALA probably makes little or no difference to heart deaths and may slightly lower events.
- DiarrheaDocumented risk
High doses may cause loose stools or diarrhea.
- Food AllergyDocumented risk
Allergic reactions to flaxseed and its oil have been reported.
Documented risks and interactions (3)
- Flaxseed oil and blood-thinning medicines. NCCIH says there are theoretical reasons flaxseed oil could interact with anticoagulant or antiplatelet drugs; the Linus Pauling Institute says high doses may inhibit platelet aggregation.
- Allergy and digestive effects. Reactions to flaxseed and its oil, including anaphylaxis, have been reported; high doses may cause loose stools, bloating and diarrhea.
- Pregnancy and breastfeeding. NCCIH says little is known about whether flaxseed oil is safe in pregnancy or breastfeeding.
Frequently asked questions
Is flaxseed oil as good as fish oil?
No, they are different. Flaxseed oil gives ALA; the body converts only part of it to EPA, and little to DHA. [8] [2] Fish oil supplies EPA and DHA directly. See flaxseed oil vs fish oil.
Does flaxseed oil lower cholesterol?
The overweight-adult analysis found slightly higher LDL cholesterol with ALA from flax products. [6] NCCIH's page did not report a cholesterol benefit for the oil. [3] We did not find good evidence that the oil lowers cholesterol.
Is flaxseed oil safe with blood thinners?
NCCIH says there are theoretical reasons it could interact with anticoagulant or antiplatelet drugs. [3] Ask your pharmacist or clinician.
Can I cook with flaxseed oil?
We did not read a source with a safe cooking temperature for it, so we give none. Polyunsaturated fats oxidize more easily. [8] See the smoke point page for how to think about heating oils.
Does flaxseed oil cause cancer?
The sources we read do not show that. A large cohort meta-analysis saw a slightly higher cancer death risk with higher ALA intake and lower overall and cardiovascular death; a prostate analysis was inconclusive. [10] [11] These are observational findings.
References
- U.S. Department of Agriculture. FoodData Central: Oil, flaxseed, cold pressed (SR Legacy, FDC 167702). April 2018 release. Read 2026-10-24.
- Brenna JT et al. alpha-Linolenic acid supplementation and conversion to n-3 long-chain polyunsaturated fatty acids in humans. Prostaglandins Leukot Essent Fatty Acids 2009 (abstract read via Europe PMC). Read 2026-10-24.
- National Center for Complementary and Integrative Health (NCCIH). Flaxseed and Flaxseed Oil. Last updated February 2025. Read 2026-10-24.
- McNabb TB et al. Supplementation of Olive Oil and Flaxseed Oil on Blood Pressure and Inflammation in Healthy and At-Risk Adults. 2024 (abstract read via Europe PMC). Read 2026-10-24.
- Tabrizi R et al. The impact of flaxseed oil on lipid profiles, weight loss, and inflammatory markers in hemodialysis patients. 2024 (abstract read via Europe PMC). Read 2026-10-24.
- Yin S et al. Effect of Alpha-Linolenic Acid Supplementation on Cardiovascular Disease Risk Profile in Individuals with Obesity or Overweight. 2023 (abstract read via Europe PMC). Read 2026-10-24.
- Su H et al. Effect of dietary alpha-linolenic acid on blood inflammatory markers: a systematic review and meta-analysis of randomized controlled trials. Eur J Nutr 2018 (abstract read via Europe PMC). Read 2026-10-24.
- Linus Pauling Institute, Oregon State University. Essential fatty acids. Read 2026-10-24.
- Abdelhamid AS et al. Omega-3 fatty acids for the primary and secondary prevention of cardiovascular disease. Cochrane Database Syst Rev 2020 (abstract read via Europe PMC). Read 2026-10-24.
- Naghshi S et al. Dietary intake and biomarkers of alpha linolenic acid and risk of all cause, cardiovascular, and cancer mortality. BMJ 2021 (abstract read via Europe PMC). Read 2026-10-24.
- Carleton AJ et al. Case-control and prospective studies of dietary alpha-linolenic acid intake and prostate cancer risk: a meta-analysis. BMJ Open 2013 (abstract read via Europe PMC). Read 2026-10-24.
- U.S. Department of Agriculture and U.S. Department of Health and Human Services. Dietary Guidelines for Americans, 2020-2025. Chapter 1 (oils and the 2,000-calorie pattern table). Read 2026-10-24.
- NHS. Different fats in food (saturated, monounsaturated and polyunsaturated). Read 2026-10-24.
- Chiang KM et al. Particulate matters, aldehydes, and polycyclic aromatic hydrocarbons produced from deep-frying emissions: comparisons of three cooking oils with distinct fatty acid profiles. 2022 (abstract read via Europe PMC). Read 2026-10-24.