Flaxseed and fish both serve as valuable sources of omega-3 fats, but the fatty acids they contain differ in some ways. You can get the omega-3s from both sources by consuming the whole food or in supplement form as oils extracted from flax or fish. Understanding the difference between the different types of omega-3 fatty acids can help you decide which source works best for you.
Omega-3 Fatty Acids
Omega-3 fatty acids are a type of polyunsaturated fat. They contain multiple double bonds, with one of those double bonds always located at the third carbon of the fatty acid chain, thus giving these fatty acids their name. The human body cannot produce omega-3 fatty acids, so they are considered essential fats, the kind you need to get through diet. However, the body can convert the most basic type of omega-3 fatty acid, alpha-linolenic acid, or ALA, into longer-chain omega-3 fats.
Flaxseed Omega-3s
The omega-3 fatty acids in flaxseed consist entirely of ALA, an omega-3 fat that is 18 carbons long. ALA has little biological activity on its own, but the body adds more carbon atoms and another double bond to create two other omega-3 fatty acids, eicosapentaenoic acid, or EPA, and docosahexaenoic acid, or DHA. These two fatty acids provide most of the publicized benefits of omega-3 fats, including boosting brain health, preventing heart disease, improving joint health and supporting fetal development during pregnancy.
Fish Oil Omega-3s
The omega-3 fatty acids in fish oil consist of a blend of EPA and DHA, which is preformed in the bodies of fish. Different fish contain different ratios of EPA to DHA, and different brands of fish oil supplements can also have different amounts of these two fats. The benefits of DHA tend to be focused more on brain health, while EPA seems to help the joints more. Both fats contribute to cardiovascular health.
Considerations
While your body can convert ALA to DHA and EPA, the conversion process does not work efficiently. Women convert about 9 percent of ALA into DHA and 21 percent into EPA, and men convert between 0 and 4 percent of ALA into DHA and 8 percent into EPA, according to the Linus Pauling Institute at Oregon State University. Consuming fish oil or fatty fish provides a more direct intake of EPA and DHA and can ensure that your body gets enough of these valuable fats. Vegans and others who do not each fish might need to consume higher amounts of ALA-containing foods, such as flax, in order to get enough for their bodies to synthesize sufficient EPA and DHA. Women should try to get at least 1,100 mg and men should get 1,600 mg of omega-3 fatty acids per day, according to the Food and Nutrition Board of the Institute of Medicine.
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