Plant Sources of Omega-3 (ALA): Flax, Chia, Walnuts, Hemp and Greens Compared
ALA amounts in flaxseed, chia, walnuts, hemp, plant oils, soy and leafy greens from USDA data, plus what research says about how little ALA the body turns into EPA and DHA.
Content last updated . This page has not been medically reviewed.
Quick answer
Plant foods supply ALA (alpha-linolenic acid), the plant omega-3. MedlinePlus lists ground flaxseed and flaxseed oil, walnuts, chia seeds, canola and soy oil, and soybeans and tofu as plant sources, and says ground flaxseed and flaxseed oil have the most ALA of the plant foods. [1] ALA is not the same as the EPA and DHA in fish. The body can convert some ALA into EPA and DHA, but a review describes that conversion as limited and affected by factors such as dose, sex and disease. [2] For a full explanation see ALA, EPA and DHA: differences and conversion limits.
Amounts of ALA in common plant foods
USDA FoodData Central (SR Legacy, April 2018 release) reports grams of fatty acid per 100 grams of food. [3] Where USDA lists a measured ALA value we use it. For some foods the database reports only a combined "18:3" figure, which we label as such; for hemp, where both are listed, the ALA-only value is lower than the combined one. [3] Portion amounts below are our calculation from USDA's gram weights.| Food | ALA, g per 100 g | Portion (USDA weight) | ALA in portion (calculated) |
|---|---|---|---|
| Flaxseed oil, cold pressed | 53.4 | 1 tablespoon (13.6 g) | about 7.3 g |
| Flaxseed (seeds), combined 18:3 | 22.8 | 1 tablespoon whole (10.3 g) or ground (7 g) | about 2.3 g whole; 1.6 g ground |
| Chia seeds, dried | 17.8 | 1 ounce (28.35 g) | about 5.1 g |
| Walnuts, English, combined 18:3 | 9.1 | 1 ounce (28.35 g, 14 halves) | about 2.6 g |
| Hemp seeds, hulled | 8.7 | 3 tablespoons (30 g) | about 2.6 g |
| Walnut oil, combined 18:3 | 10.4 | not read | not calculated |
| Canola oil | 9.1 | 1 tablespoon (14 g) | about 1.3 g |
| Soybean oil | 6.8 | not read | not calculated |
| Soybeans, mature, raw, combined 18:3 | 1.3 | not read | not calculated |
| Tofu, raw, firm, combined 18:3 | 0.58 | not read | not calculated |
| Edamame, frozen, prepared | 0.36 | not read | not calculated |
| Kale, raw, combined 18:3 | 0.38 | not read | not calculated |
| Basil, fresh, combined 18:3 | 0.32 | not read | not calculated |
| Spinach, raw, combined 18:3 | 0.14 | not read | not calculated |
| Olive oil, combined 18:3 | 0.76 | not read | not calculated |
Source for every row: USDA FoodData Central, SR Legacy, 2018. [3] Purslane has no ALA value in this USDA dataset, so we do not give one.
Two cautions. First, oils and seeds are concentrated, so a spoonful of flaxseed oil holds far more ALA than a serving of greens. Second, one database entry is one sample; real products vary.
What the body does with ALA
- Conversion is limited. A review of human studies found conversion of ALA to EPA, and to a lesser degree DHA, in men, with limited conversion to DHA; conversion was greater in women than men, possibly because of oestrogen. [4]
- Blood levels of EPA plus DHA. A scoping review of 13 randomized trials (2010 to 2020) found that high-dose flaxseed or echium seed oil did not raise the omega-3 index (the share of EPA plus DHA in red blood cells) and some studies showed reductions, whereas microalgal oil raised it in all studies. [5] This is a biomarker result, not a health outcome, in mostly small trials.
- Health outcomes of plant ALA foods. Proper evidence not found in the sources we read for trials proving that eating flax, chia or walnuts prevents a disease. We searched PubMed for ALA metabolism and plant-omega-3 bioavailability, not for every disease. The flaxseed, chia and walnut food pages cover each food.
Official reference values
| Body, year | What it says | Note |
|---|---|---|
| EFSA, 2009 (labelling opinion) | Proposed labelling reference intake value for ALA is 2 g, and 250 mg for EPA plus DHA [6] | A label value for EU food labels, not a personal requirement |
| EFSA, 2012 news release | 250 mg a day of EPA plus DHA described as an adequate intake [7] | Applies to EPA plus DHA, not ALA |
| NIH Office of Dietary Supplements | Adequate Intake for ALA could not be verified: the page returned an access error | We do not quote it from memory |
For more intake tables see omega-3 intake reference tables.
Vegetarians, vegans and other practical points
- People who eat no fish rely on ALA foods or on algal oil for DHA; see omega-3 for vegetarians and vegans. The head-to-head oils are on chia, hemp, perilla and walnut oils and flaxseed oil and plant-based omega-3.
- Hemp seed oil is a food oil; it is not CBD oil. See hemp foods and hemp seed oil.
- Walnuts and seeds are common allergens for some people; anyone with a nut or seed allergy should ask an allergist before adding them.
- Anyone on prescribed medicines, or with kidney or liver conditions, or planning surgery, should ask a clinician or pharmacist before making big changes or adding concentrated oils. See medication interactions.
Frequently asked questions
Which plant food has the most omega-3?
In USDA data, flaxseed oil has the most ALA per 100 g, then flaxseed, then chia seeds. [3]
Is ALA as good as fish omega-3?
They are different fats. ALA conversion to EPA and especially DHA is limited. [4] In one review, flaxseed oil did not raise the omega-3 index in trials. [5]
Do leafy greens have omega-3?
USDA lists small amounts of ALA in kale, spinach and basil compared with seeds and oils. [3]
Is chia better than flaxseed for omega-3?
USDA lists more 18:3 per 100 g in flaxseed than ALA in chia seeds. [3] The ALA in a portion depends on how much you weigh out (see the table). Proper evidence not found for a head-to-head trial of the two in the sources we read.
Can vegans get DHA from plants?
Plant foods give ALA, not DHA. A review found microalgal oil raised the omega-3 index. [5]
References
- MedlinePlus, Omega-3 fats - Good for your heart. Read 2026-10-23.
- The review of alpha-linolenic acid: sources, metabolism, and pharmacology. Phytother Res 2022. Read 2026-10-23.
- USDA FoodData Central, SR Legacy dataset (April 2018 release, CSV download). Read 2026-10-23.
- Metabolism of alpha-linolenic acid in humans. Prostaglandins Leukot Essent Fatty Acids 2006. Read 2026-10-23.
- Bioavailability and conversion of plant based sources of omega-3 fatty acids: a scoping review. Crit Rev Food Sci Nutr 2022. Read 2026-10-23.
- EFSA Journal 2009;1176, Labelling reference intake values for n-3 and n-6 polyunsaturated fatty acids (copy on a third-party mirror). Read 2026-10-23.
- EFSA, EFSA assesses safety of long-chain omega-3 fatty acids (news story, 27 July 2012). Read 2026-10-23.
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.