Both flaxseeds and fish oil are good dietary sources of omega-3 fatty acids -- essential nutrients that are critical for proper brain functioning and may reduce risk factors for heart disease. However, because flaxseeds and fish oil supply different kinds of omega-3s, flaxseeds and fish oil are associated with different health advantages and risks. It is best to consult your doctor before taking any dietary supplement, especially if you have a health condition or are taking medication.
Flaxseeds: Health Benefits and Concerns
Flaxseeds are a good source of omega-3 fatty acids and fiber. Flaxseed oil can also be taken in nutritional supplements which contain concentrated flaxseed extract. Medline Plus rates flaxseed as "possibly effective" for treating the following conditions: high blood sugar in people with type 2 diabetes; high cholesterol; poor kidney functioning in people with lupus; and relieving mild menopausal symptoms.
According to Medline Plus, flaxseeds are "likely safe" for most people, excluding pregnant women and people with bleeding disorders, who should not take flaxseed. Phytochemicals called lignans are thought to be responsible for many of flaxseed's health benefits, although there is some concern that the lignans in flaxseed, and particularly in concentrated flaxseed extract, may also worsen estrogen-dependent conditions such as breast cancer or endometriosis, according to Medline Plus.
Fish Oil: Health Benefits and Concerns
Fish oil is another source of dietary omega-3s, which can be obtained by eating fish or taking supplements. The health benefits of fish are more established than those for flaxseeds. According to MedlinePlus, fish oil is an "effective" treatment for lowering high triglyceride levels associated with heart disease, and fish oil is "likely effective" in preventing heart disease and heart attacks. Fish oil is "possibly effective" in treating other conditions including high blood pressure, depression, menstrual pain and others. Fish oil is "likely safe" for most people, including pregnant and breastfeeding women, when taken in low doses of 3 g or less per day. Although large fish such as shark, king mackerel and farm-raised salmon can be contaminated with mercury and industrial chemicals, high-quality fish oil supplements typically don't contain these contaminants, says Medline Plus.
Short- vs. Long-Chain Omega 3s
Flaxseeds and fish oil contain different types of omega 3 fatty acids, which may account for their different health effects. Flax seeds contain alpha-linolenic acid or ALA, whereas fish oil provides eicosapentaenoic acid --EPA -- and docosahexaenoic acid, or DHA. Unlike EPA and DHA, the so-called "long-chain" forms of omega-3 that the body can readily use, ALA is a "short-chain" omega-3 which your body must convert to a long chain version in order to use.
According to Walter Willett, chair of the department of nutrition at the Harvard School of Public Health, there is some question as to whether the body is able to effectively make this short- to long-chain conversion, and it is therefore likely that EHA and DHA sources like fish oil carry more health benefits than ALA sources like flaxseeds.
Vegetarian Omega-3 Sources
Vegetarians may prefer to take flaxseeds over fish oil because, unlike fish, flax is a vegetarian source of omega-3s. However, people who only get ALA omega-3 sources like flaxseeds may be missing out on some of the health benefits provided by sources of EPA and DHA. Several other plant foods, such as walnuts, soybeans and canola oil, also provide omega-3s, but these are ALA sources as well.
Fortunately, there is one vegetarian food which supplies DHA: algae. Algae-derived DHA may also be a good omega-3 source for pregnant women, who need DHA for the health of their developing babies but must limit their fish intake due to mercury concerns.
References
- University of Maryland Medical Center: Omega-3 Fatty Acids
- Medline Plus: Flaxseed
- Medline Plus: Fish Oil
- U.S. News and World Report; Fish Oil Supplements, EPA, DHA, and ALA: Does Your Omega-3 Source Matter?; Sarah Baldauf; April 2009
- NPR; Getting Brain Food Straight from the Source; Allison Aubrey; November 2007
Member Comments