What omega-3 is, and where it comes from

Omega-3 is a family of fats your body cannot make enough of. Seeds, nuts and some oils give one kind; fish and algae give 2 more, EPA and DHA.

KiloCare Team · October 23, 2026 · 3 min read · How we write and review

A round board with half a walnut, a spoon of flaxseeds and a fish fillet, set apart on pale oak. — Fish, flaxseed and walnuts carry omega-3.

A family of fats

Omega-3s and omega-6s are the 2 main groups of one type of fat, called polyunsaturated fat.^[1] Several omega-3s exist, and the research mostly looks at 3 of them: ALA, EPA and DHA. EPA and DHA have longer chains, so they are called long-chain omega-3s.^[1]

Omega-3s are part of the outer layer of every cell in the body, the cell membrane. DHA is found in high amounts in the brain, in sperm and in the retina at the back of the eye. Along with omega-6s, omega-3s also give the body energy.^[1]

Plant omega-3 (ALA)

Your body cannot make ALA, so ICMR-NIN, India's National Institute of Nutrition, calls it an essential fat, along with linoleic acid, an omega-6 fat.^[2]

In Indian food, ALA comes from mustard (sarson) oil, soybean, flaxseed (alsi), walnuts (akhrot), chia seeds and fenugreek seeds (methi). Pulses, beans and green leafy vegetables have it too.^[2]

ICMR-NIN reports that Indian diets are generally low in ALA, unless the family cooks with mustard, soybean or flaxseed oil. Its 2020 report says many urban, higher-income Indians in the studies it reviewed had low omega-3 levels in their blood.^[3]

The fish kind (EPA and DHA)

Tiny algae at the base of the sea's food chain make EPA and DHA. Fish take them in as they feed, and store them in their bodies.^[1]

Oily sea fish such as mackerel, sardines, salmon and tuna contain high amounts. Shellfish contain less.^[1] ICMR-NIN also names eggs as a natural source.^[2]

ICMR-NIN says EPA and DHA are more active in the body than the ALA in plant foods.^[2]

EPA and DHA are also sold as supplements: fish oil, krill oil, cod liver oil, and vegetarian algal oil.^[1] Each gives EPA and DHA. Some algal oils give only DHA.^[1]

How much ALA the body turns into EPA and DHA

Your body can turn ALA into EPA, and EPA into DHA. This happens mostly in the liver. The US National Institutes of Health (NIH) calls the change very limited.

15%

is the ceiling: reported rates of ALA becoming EPA and DHA fall below it.

The NIH calls the change very limited.^[1]

How the body turns ALA into EPA and DHA

ALA comes in from seeds, oils, pulses and greens.
The liver turns a small share of it into EPA.
Some of that EPA becomes DHA.

ICMR-NIN describes the change as slow and uneven.^[3] Our article on omega-3, 6 and 9 explains how omega-6 fats affect it.

The NIH says the only practical way to raise EPA and DHA in the body is to eat them directly. That means from food or from supplements.^[1]

Plant and fish omega-3 side by side

At a glance
	Plant omega-3 (ALA)	Fish omega-3 (EPA and DHA)
Where it comes from	Mustard oil, soybean, flaxseed, walnuts, chia and fenugreek seeds, pulses and greens	Oily sea fish such as mackerel and sardines, shellfish and eggs
Can your body make it?	No. It has to come from food.	Only a small share, made from ALA
In the body	Less active than EPA and DHA	More active than ALA

If you eat no fish or eggs, your EPA and DHA depend on the ALA you eat.

ICMR-NIN's first advice for people who eat no fish is to eat more plant omega-3 (ALA).^[3] An algal oil supplement is another way to get DHA. Ask your doctor or a dietitian whether you need one. Our article on getting omega-3 from Indian food lists the foods, with and without fish.

Ask your doctor before you take an omega-3 supplement if you take a blood thinner or any medicine regularly, are pregnant or breastfeeding, or are buying it for a child.

If you have a fish or shellfish allergy, ask your doctor before you take fish or krill oil.

Do not take more than the pack says.

Medical disclaimer: This article is general information. It does not replace advice from your doctor about your own health.

Common questions

Is the omega-3 in flaxseed the same as the omega-3 in fish?+

No. Flaxseed contains ALA, the omega-3 in plants. Fish contains 2 other omega-3s, EPA and DHA.

Can the body make its own omega-3?+

Your body cannot make ALA, so it has to come from food. It can turn some ALA into EPA and DHA, but the change is slow and very limited.

Sources

National Institutes of Health, Office of Dietary Supplements. Omega-3 fatty acids: fact sheet for health professionals [Internet]. National Institutes of Health; 2025 Aug 22 [cited 2026 Oct 23]. Available from: ods.od.nih.govCited atIntroduction, paras 1-2 Introduction, para 1 Introduction, para 7 Introduction, para 5 Sources of omega-3s, Food, para 2 Sources of omega-3s, Dietary supplements, para 1 Sources of omega-3s, Dietary supplements, para 4 Introduction, para 4 Introduction, para 4
ICMR-NIN Expert Committee. Dietary Guidelines for Indians - 2024. Hyderabad: ICMR-National Institute of Nutrition; 2024. Available from: nin.res.inCited atGuideline 7, p. 51 Guideline 7, p. 53 Guideline 7, p. 53 Guideline 7, p. 52
ICMR-National Institute of Nutrition. Nutrient requirements for Indians: recommended dietary allowances and estimated average requirements, 2020. A report of the expert group. Hyderabad: ICMR-NIN; 2020. Updated 2024. Available from: nin.res.inCited atp. 106 p. 100 p. 115