Both fish and flaxseed oils contain the essential fatty acid omega-3. Many studies link omega-3 to health benefits such as reduced risk of heart disease. You'll find both as supplements in pill form in health food stores. However, fish oil appears to offer a more concentrated and effective form of omega-3 in most cases, though taking high doses may trigger some negative side effects. Speak with your doctor before taking large amounts of fish or flaxseed oil.
Coronary Heart Disease
Jane Higdon, Ph.D. at the Linus Pauling Institute outlines several reliable studies that appear to confirm that fish oil helps prevent coronary heart disease. For example, one study following 1,822 men over 30 years found that men who ate 1.2 oz. of fish each day were 38 percent less likely to suffer coronary heart disease. They were also 67 percent less likely to die from myocardial infarction. Similarly, the Nurses' Health Study found that the risk of CHD was 29 to 34 percent lower in women eating fish every week than women who ate fish only once per month.
Problems
A Harvard Health Publications report suggests that while fish oil benefits those with a generally healthy heart or some heart conditions, it may not help those with serious angina or ventricular tachycardia. Studies suggest that the omega-3 found in fish oil reduces erratic heart rhythms. However, in some cases these erratic pulses keep the heart working -- particularly in people with angina. Some people also react to fish oil supplements with some bleeding or unpleasant feelings in the gut. Your doctor should advise whether fish oil supplements suit your situation.
Flaxseed Oil
Flaxseed oil contains a different form of omega-3 fatty acid to fish oil known as alpha-linolenic acid, or ALA. According to the Harvard Medical School Family Health Guide, you must take more flaxseed to get the same benefits from omega-3 as fish oil. However, a 1995 study published in the "European Journal of Clinical Nutrition" showed that daily flaxseed supplements appear to reduce the risk of cardiovascular disease. Yet, even this study featured very large doses of flaxseed oil -- 40 g per day.
Gradings
Mayo Clinic graded the evidence of omega-3 benefits for a range of conditions based on available scientific studies. For example, an A grade means that strong scientific evidence exists to back up claims of efficacy. A D grade means that the substance may not work, but some evidence may suggest a link. In terms of omega-3 fatty acids such as those found in fish oils and flaxseed oils, Mayo Clinic lists high blood pressure, blood triglyceride levels and cardiovascular disease with an A grade as of April 2011. Diabetes, hypercholesterolemia and transplant rejection prevention all get D grades.
References
- Linus Pauling Institute; Essential Fatty Acids; Jane Higdon, Ph.D.; Apr, 2009
- Harvard Health Publications HEALTHbeat; Fish and Fish Oil: Good For Most Folks, But Not All; 2008
- Mayo Clinic; Omega-3 Fatty Acids, Fish Oil, Alpha-linolenic Acid; April 1, 2011
- "European Journal of Clinical Nutrition"; Supplementation With Flaxseed Oil Versus Sunflowerseed Oil in Healthy Young Men Consuming a Low Fat Diet: Effects On Platelet Composition and Function; MA Allman, et al.; March 1995
- Harvard Medical School Family Health Guide; Why Not Flaxseed Oils?; November 2006
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