Omega-6 fatty acids

Food sources of linoleic acid (LA) include vegetable oils, such as soybean, safflower, corn oil as well as nuts, seeds, and some vegetables (215). Animals, but not plants, can convert LA to arachidonic acid (AA). Therefore, AA is present in small amounts in meat, poultry, and eggs.

Omega-3 fatty acids

Flaxseeds, walnuts, and their oils are among the richest dietary sources of alpha-linolenic acid (ALA). Canola oil is also an excellent source of ALA.

Oily fish, such as herring and salmon, are the major dietary source of long-chain omega-3 polyunsaturated fatty acids, eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). 

Humans can synthesize AA from LA and EPA and DHA from ALA, but the conversion rate of ALA to DHA is very limited.


Omega-6 fatty acids

Borage seed oil, evening primrose oil, and black currant seed oil are rich in gamma-linolenic acid (GLA) and are often marketed as GLA or essential fatty acid (EFA) supplements (216).

Omega-3 fatty acids

A number of fish oils are marketed as omega-3 fatty acid supplements. Ethyl esters of EPA and DHA (ethyl-EPA and ethyl-DHA) are concentrated sources of long-chain omega-3 fatty acids. Since EPA and DHA content will vary in fish oil and ethyl ester preparations, it is necessary to read the label to determine the EPA and DHA content of a particular supplement. DHA supplements derived from algal and fungal sources are also available.

All omega-3 fatty acid supplements are absorbed more efficiently with meals. Dividing one’s daily dose into two or three smaller doses throughout the day will decrease the risk of gastrointestinal side effects. Cod liver oil is a rich source of EPA and DHA.

Infant formula

In the U.S. and many countries around the world, adding DHA and AA to infant formula is permitted (217). In the U.S., adding DHA and AA to infant formula is permitted (217). The amounts added to formulas range from 8 to 17 mg DHA/100 calories and from 16 to 34 mg AA/100 calories.


Authored by Dr Peter Engel in 2010, reviewed and revised by Karin Yurko-Mauro on 12.06.2017.