ALA (alpha-linolenic acid) is one of the three main omega-3 fatty acids. The other two omega-3s (eicosapentaenoic acid [EPA] and docosahexaenoic acid [DHA]) generally receive more scientific scrutiny than ALA and are credited with many health benefits, with evidence most promising for cardiovascular conditions such as preventing heart attack and high blood pressure, and fighting inflammation.
One reason ALA does not get the attention it deserves is that it must be converted in the body, first to EPA, then DPA (docosapentaenoic acid), and then finally to DHA. Unfortunately, the conversion rate is believed to be very low, only about 10 percent according to some studies, and between 8 and 20 percent converted to EPA and 0.5 to 9 percent converted to DHA in others. In addition, women of reproductive age reportedly convert ALA to EPA at a 2.5-fold greater rate than healthy men. (Stark 2008) The conversion is also influenced by the presence of the omega-6 fatty acid linoleic acid: the higher the amount of linoleic acid in the body, the poorer the conversion rate of ALA to DHA.
Unlike EPA and DHA, which are found in fatty fish, ALA is obtained from plant sources, with a high concentration found in flaxseed and flaxseed oil and, to a lesser degree, in canola, soy, perilla, chia, hemp, pumpkin seed, and walnut oils. ALA is also found in walnuts, pumpkin seeds, tofu, and fortified foods, and in some green vegetables, including Brussel sprouts, kale, and spinach. If you are getting all the ALA you need in your diet from oils and nuts, there is generally no need to take a supplement. However, an algae DHA supplement, which is derived from algae rather than from fish, can help when dietary sources are insufficient.
Foods that contain ALA include:
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Flaxseed and flaxseed oil |  |
Canola oil |
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Walnuts |  |
Pumpkin seeds |
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Chia seeds and chia oil |  |
Hemp oil |
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Soybean oil |  |
Fortified foods |
References
Coates W. ALA conversion to EPA, DPA and DHA. 2009. http://www.eatchia.com/ALA%20Conversion.htm
Stark AH et al. Update on alpha-linolenic acid. Nutrition Reviews 2008; 66(6): 326-32
See also
