Fish oil supplements vary in the amounts and ratios of DHA and EPA they contain. For example, salmon oil naturally contains more DHA than EPA; a supplement derived from algae may only contain DHA. Krill oil contains significant amounts of both EPA and DHA. Read the labels and remember whatever supplement you buy, it must have at least 600 mg of DHA.
^ Jump up to: a b Hooper L, Thompson RL, Harrison RA, Summerbell CD, Ness AR, Moore HJ, Worthington HV, Durrington PN, Higgins JP, Capps NE, Riemersma RA, Ebrahim SB, Davey Smith G (2006). "Risks and benefits of omega−3 fats for mortality, cardiovascular disease, and cancer: systematic review". BMJ. 332 (7544): 752–60. doi:10.1136/bmj.38755.366331.2F. PMC 1420708. PMID 16565093. Retrieved 2006-07-07.[permanent dead link]
Omega−3 fatty acids are important for normal metabolism. Mammals are unable to synthesize omega−3 fatty acids, but can obtain the shorter-chain omega−3 fatty acid ALA (18 carbons and 3 double bonds) through diet and use it to form the more important long-chain omega−3 fatty acids, EPA (20 carbons and 5 double bonds) and then from EPA, the most crucial, DHA (22 carbons and 6 double bonds). The ability to make the longer-chain omega−3 fatty acids from ALA may be impaired in aging. In foods exposed to air, unsaturated fatty acids are vulnerable to oxidation and rancidity.
High levels of the oils in blood samples were linked with a 71 per cent increased risk of developing an aggressive and dangerous form of prostate cancer, according to the research. That study, if I recall correctly, mentioned concern about men eating fish more than a certain number of times a week having a 54% increased risk of developing prostate cancer.
Only fish and breast milk contain all the members of the omega-3 family, including its two main stars, EPA and DHA. Because Americans as a rule consume far too few omega-3s from fish or fish oil, it’s no surprise that the majority of Americans have low omega-3 index levels as well. A recent study of global omega-3 index levels found that an estimated 95% of Americans (with the exception of folks from Alaska) had an omega-3 index of 4 or below, putting them in the high risk category (5, 6, 7).
The number of presenters and the amount of information stuffed into an action-packed few days at times felt overwhelming, even for two dedicated omega-3 enthusiasts like us. But one important message did hit home: The omega-3 index could be a helpful indicator of various health risks, and we should all be paying closer attention to this measurement.
Henneicke-von Zepelin, H. H., Mrowietz, U., Farber, L., Bruck-Borchers, K., Schober, C., Huber, J., Lutz, G., Kohnen, R., Christophers, E., and Welzel, D. Highly purified omega-3-polyunsaturated fatty acids for topical treatment of psoriasis. Results of a double-blind, placebo-controlled multicentre study. Br J Dermatol 1993;129(6):713-717. View abstract.
Hooper, L., Thompson, R. L., Harrison, R. A., Summerbell, C. D., Ness, A. R., Moore, H. J., Worthington, H. V., Durrington, P. N., Higgins, J. P., Capps, N. E., Riemersma, R. A., Ebrahim, S. B., and Davey, Smith G. Risks and benefits of omega 3 fats for mortality, cardiovascular disease, and cancer: systematic review. BMJ 4-1-2006;332(7544):752-760. View abstract.
Another study conducted by researchers at Rhode Island Hospital examined the relationship between fish oil supplementation and indicators of cognitive decline. The subjects of the study were older adults: 229 cognitively normal individuals, 397 patients with mild cognitive impairment and 193 patients with Alzheimer’s disease. They were assessed with neuropsychological tests and brain magnetic resonance imaging every six months while taking fish oil supplements. The study found that the adults taking fish oil (who had not yet developed Alzheimer’s and did not have genetic risk factor for developing Alzheimer’s known as APOE ε4) experienced significantly less cognitive decline and brain shrinkage than adults not taking fish oil. (9)
Most leafy green vegetables have significant amounts of omega-3, and spinach is no exception. Despite its villainous reputation, raw spinach actually has a mild flavor, making it an ideal base for salads or a crunchy addition to sandwiches. Many people add spinach to eggs, soups, or pasta dishes without impacting flavor. If you’re dealing with a particularly picky eater, though, try some of the recipes in Jessica Seinfeld’s Deceptively Delicious — her spinach and carrot brownies are tasty, healthy, and chocolaty to boot!
Several large studies have linked higher blood levels of long-chain omega-3s with higher risks of prostate cancer. However, other research has shown that men who frequently eat seafood have lower prostate cancer death rates and that dietary intakes of long-chain omega-3s aren’t associated with prostate cancer risk. The reason for these apparently conflicting findings is unclear.
Birch, E. E., Carlson, S. E., Hoffman, D. R., Fitzgerald-Gustafson, K. M., Fu, V. L., Drover, J. R., Castaneda, Y. S., Minns, L., Wheaton, D. K., Mundy, D., Marunycz, J., and Diersen-Schade, D. A. The DIAMOND (DHA Intake And Measurement Of Neural Development) Study: a double-masked, randomized controlled clinical trial of the maturation of infant visual acuity as a function of the dietary level of docosahexaenoic acid. Am J Clin Nutr 2010;91(4):848-859. View abstract.
Despite this one study, you should still consider eating fish and other seafood as a healthy strategy. If we could absolutely, positively say that the benefits of eating seafood comes entirely from omega-3 fats, then downing fish oil pills would be an alternative to eating fish. But it’s more than likely that you need the entire orchestra of fish fats, vitamins, minerals, and supporting molecules, rather than the lone notes of EPA and DHA.
The American Heart Association (AHA) has made recommendations for EPA and DHA due to their cardiovascular benefits: individuals with no history of coronary heart disease or myocardial infarction should consume oily fish two times per week; and "Treatment is reasonable" for those having been diagnosed with coronary heart disease. For the latter the AHA does not recommend a specific amount of EPA + DHA, although it notes that most trials were at or close to 1000 mg/day. The benefit appears to be on the order of a 9% decrease in relative risk. The European Food Safety Authority (EFSA) approved a claim "EPA and DHA contributes to the normal function of the heart" for products that contain at least 250 mg EPA + DHA. The report did not address the issue of people with pre-existing heart disease. The World Health Organization recommends regular fish consumption (1-2 servings per week, equivalent to 200 to 500 mg/day EPA + DHA) as protective against coronary heart disease and ischaemic stroke.
Recent studies have shown that the consumption of fish oil (or, more specifically, the omega-3 fatty acids found in fish oil) can improve fertility in both men and women. DHA, which is a byproduct of omega-3 fatty acids, plays a key role in the mobility of sperm and health of sperm in men. Low blood levels of DHA have been linked to decreased fertility. Animal studies have found that the DHA in fish is vital to changing dysfunctional round-headed sperm into strong swimmers with cone-shaped heads packed with egg-opening proteins. (29)
Attention deficit-hyperactivity disorder (ADHD) in children. Early research shows that taking fish oil improves attention, mental function, and behavior in children 8-13 years-old with ADHD. Other research shows that taking a specific supplement containing fish oil and evening primrose oil (Eye Q, Novasel) improves mental function and behavior in children 7-12 years-old with ADHD.