Alpha-Linolenic Acid

fatty acidalpha-linolenic acid

Take with food

What is it

Alpha-linolenic acid (ALA) is the plant-source omega-3 fatty acid found in flaxseed, chia, walnuts, and certain oils. It is an essential fatty acid — the body cannot make it — and serves as the only omega-3 in many vegetarian and vegan diets.

How it works

ALA is incorporated into cell membranes and used as an energy substrate. A small percentage is converted by elongase and desaturase enzymes into longer-chain EPA and DHA, which have more potent effects on cardiovascular and brain function. In adults, this conversion is inefficient — typically less than 10 percent of ALA becomes EPA, and less than 1 percent becomes DHA. Women generally convert slightly more efficiently than men, partly due to estrogen. On its own, ALA contributes to cardiovascular health and provides essential fatty acid status. For people who do not eat fish, algal oil provides a more direct source of DHA without relying on inefficient conversion.

Evidence for 4 uses

AI-assisted evidence assessment — talk to your doctor before relying on any single supplement.

Essential fatty acid sufficiency

Grade A

Strong evidence

ALA is an essential fatty acid; adequate intake prevents essential fatty acid deficiency.

Cardiovascular health

Grade B

Good evidence

Observational studies link higher ALA intake to reduced cardiovascular mortality. Some randomized trials support modest benefit; effect is smaller than for EPA+DHA.

Inflammation reduction

Grade C

Moderate evidence

ALA modestly reduces inflammatory markers like CRP in some trials. Effect is smaller than for EPA+DHA.

Source of EPA and (limited) DHA

Grade C

Moderate evidence

ALA converts to EPA and DHA, but inefficiently. For people relying on plant sources, this is the main pathway to long-chain omega-3s.

Dosage

The Adequate Intake for ALA is 1.6 grams per day for men and 1.1 grams per day for women. Most people meet this from regular consumption of plant foods. A tablespoon of ground flaxseed provides about 1.6 grams. No tolerable upper limit is established.

When and how to take it

ALA from food can be eaten any time. Ground flaxseed sprinkled on cereal, yogurt, or smoothies is a convenient way to add it. Chia seeds can be added to drinks or used to make chia pudding. ALA in supplements (flaxseed oil capsules) should be kept refrigerated because the oil oxidizes easily.

Food sources

Food	Amount	%DV
Flaxseed oil, 1 Tbsp	7.3 g ALA	—
Chia seeds, 1 oz	5 g ALA	—
Walnuts (English), 1 oz	2.5 g ALA	—
Flaxseed (ground), 1 Tbsp	1.6 g ALA	—
Canola oil, 1 Tbsp	1.3 g ALA	—
Soybean oil, 1 Tbsp	0.9 g ALA	—
Edamame, 1/2 cup	0.3 g ALA	—
Hemp seeds, 3 Tbsp	2.6 g ALA	—

Safety

ALA from food is safe. Very high intake from supplements has been associated in some observational studies with a possible increase in advanced prostate cancer risk, though evidence is mixed and not consistent across studies. Flax seeds should be ground to be absorbed; whole flax passes through largely unabsorbed.

Who should be cautious

People with hormone-sensitive cancers should discuss high flaxseed intake with their doctor due to lignan content. Men with prostate cancer or at high risk should be aware of the (uncertain) association with advanced prostate cancer. Pregnant and breastfeeding women benefit more from direct DHA (fish or algal oil) than from relying on ALA conversion.

Interactions

At food-level intakes, no significant interactions. Flaxseed contains lignans with mild estrogen-like activity that may interact with hormone-sensitive therapies. ALA at very high doses might modestly affect bleeding risk, similar to other omega-3s.

Frequently asked questions

Is ALA enough for omega-3 needs?⌄

It covers the essential fatty acid requirement and provides cardiovascular benefit. But because conversion to EPA and DHA is inefficient, vegans and vegetarians often add algal oil for direct DHA.

Should I grind my flaxseed?⌄

Yes. Whole flaxseed passes through largely unabsorbed. Grinding releases the oil and lignans for absorption.

How much ALA do I need?⌄

1.6 g per day for men, 1.1 g for women. A tablespoon of ground flax or an ounce of walnuts provides this.

Does ALA raise prostate cancer risk?⌄

Some observational data has suggested a link with advanced prostate cancer, but evidence is mixed. Stick to food-source ALA and discuss with your doctor if you have prostate cancer risk.

Is flaxseed oil better than ground flaxseed?⌄

Flax oil is more concentrated ALA but lacks the fiber and lignans of whole ground flax. Many people use ground flax for the broader nutrient profile.

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Disclaimer: These statements have not been evaluated by the FDA. This page is educational, not a substitute for personalized medical advice. Evidence grades are AI-assisted assessments — talk to your doctor before starting any new supplement, especially if you're pregnant, breastfeeding, on medications, or managing a chronic condition.