Sekikawa, A., Curb, D., Ueshima, H., El-Saed, A., Kadowaki, T., Abbott, R. D., ... Kuller, L. H. (2008 August 5). Marine-derived n-3 fatty acids and atherosclerosis in Japanese, Japanese Americans, and Whites: a cross-sectional study. Journal of the American College of Cardiology 52(6), 417–424. Retrieved from http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2736602/
The three types of omega−3 fatty acids involved in human physiology are α-linolenic acid (ALA), found in plant oils, and eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), both commonly found in marine oils. Marine algae and phytoplankton are primary sources of omega−3 fatty acids. Common sources of plant oils containing ALA include walnut, edible seeds, clary sage seed oil, algal oil, flaxseed oil, Sacha Inchi oil, Echium oil, and hemp oil, while sources of animal omega−3 fatty acids EPA and DHA include fish, fish oils, eggs from chickens fed EPA and DHA, squid oils, and krill oil. Dietary supplementation with omega−3 fatty acids does not appear to affect the risk of death, cancer or heart disease. Furthermore, fish oil supplement studies have failed to support claims of preventing heart attacks or strokes or any vascular disease outcomes.
Omega-3 fatty acids have been shown to increase platelet responsiveness to subtherapeutic anticoagulation therapies, including aspirin. Recently, it was noted that patient response to aspirin for anticoagulation therapy is widely variable (45), and, thus, the number of patients with a low response to aspirin or aspirin resistance is estimated to range from <1% to 45%, depending on many variables. However, in patients with stable coronary artery disease taking low-dose aspirin, EPA+DHA supplementation has been proven to be as effective as aspirin dose escalation to 325 mg/d for anticoagulation benefits (45). The antiplatelet drug clopidogrel has also been associated with hyporesponsiveness in some patients. This could be attributed to poor patient compliance, differences in genes and platelet reactivity, variability of drug metabolism, and drug interactions. More importantly, in 1 study, patients receiving standard dual antiplatelet therapy (aspirin 75 mg/d and clopidogrel 600-mg loading dose followed by 75 mg/d) were assigned to either EPA+DHA supplementation or placebo. After 1 mo of treatment, the P2Y12 receptor reactivity index (an indicator of clopidogrel resistance) was significantly lower, by 22%, for patients taking EPA+DHA compared with patients taking placebo (P = 0.020) (46).
Arsenault, L. N., Matthan, N., Scott, T. M., Dallal, G., Lichtenstein, A. H., Folstein, M. F., Rosenberg, I., and Tucker, K. L. Validity of estimated dietary eicosapentaenoic acid and docosahexaenoic acid intakes determined by interviewer-administered food frequency questionnaire among older adults with mild-to-moderate cognitive impairment or dementia. Am J Epidemiol 7-1-2009;170(1):95-103. View abstract.
Gorjao, R., Verlengia, R., Lima, T. M., Soriano, F. G., Boaventura, M. F., Kanunfre, C. C., Peres, C. M., Sampaio, S. C., Otton, R., Folador, A., Martins, E. F., Curi, T. C., Portiolli, E. P., Newsholme, P., and Curi, R. Effect of docosahexaenoic acid-rich fish oil supplementation on human leukocyte function. Clin Nutr 2006;25(6):923-938. View abstract.
There have been conflicting results reported about EPA and DHA and their use with regard to major coronary events and their use after myocardial infarction. EPA+DHA has been associated with a reduced risk of recurrent coronary artery events and sudden cardiac death after an acute myocardial infarction (RR, 0.47; 95% CI: 0.219–0.995) and a reduction in heart failure events (adjusted HR: 0.92; 99% CI: 0.849–0.999) (34–36). A study using EPA supplementation in combination with a statin, compared with statin therapy alone, found that, after 5 y, the patients in the EPA group (n = 262) who had a history of coronary artery disease had a 19% relative reduction in major coronary events (P = 0.011). However, in patients with no history of coronary artery disease (n = 104), major coronary events were reduced by 18%, but this finding was not significant (37). This Japanese population already has a high relative intake of fish compared with other nations, and, thus, these data suggest that supplementation has cardiovascular benefits in those who already have sufficient baseline EPA+DHA levels. Another study compared patients with impaired glucose metabolism (n = 4565) with normoglycemic patients (n = 14,080). Impaired glucose metabolism patients had a significantly higher coronary artery disease HR (1.71 in the non-EPA group and 1.63 in the EPA group). The primary endpoint was any major coronary event including sudden cardiac death, myocardial infarction, and other nonfatal events. Treatment of impaired glucose metabolism patients with EPA showed a significantly lower major coronary event HR of 0.78 compared with the non–EPA-treated impaired glucose metabolism patients (95% CI: 0.60–0.998; P = 0.048), which demonstrates that EPA significantly suppresses major coronary events (38). When looking at the use of EPA+DHA and cardiovascular events after myocardial infarction, of 4837 patients, a major cardiovascular event occurred in 671 patients (13.9%) (39). A post hoc analysis of the data from these diabetic patients showed that rates of fatal coronary heart disease and arrhythmia-related events were lower among patients in the EPA+DHA group than among the placebo group (HR for fatal coronary heart disease: 0.51; 95% CI: 0.27–0.97; HR for arrhythmia-related events: 0.51; 95% CI: 0.24–1.11, not statistically significant) (39). Another study found that there was no significant difference in sudden cardiac death or total mortality between an EPA+DHA supplementation group and a control group in those patients treated after myocardial infarction (40). Although these last 2 studies appear to be negative in their results, it is possible that the more aggressive treatment with medications in these more recent studies could attribute to this.
Children require DHA for growth and development, and the brain, CNS and retina rely heavily on the adequate supply of DHA during growth in the womb. Thus women should emphasise DHA in their diets when they become pregnant and continue to take this until they cease breastfeeding. Children continue to need DHA up until the age they start school, so if children under the age of five are taking an omega-3 supplement, it should contain DHA. The exception is for children with developmental problems – where pure EPA or high EPA omega-3 has been shown to be most effective for supporting cognitive function. We would still recommend, where possible, naturally derived sources of omega-3 such as oily fish to support a balanced EPA and DHA intake.
Your retina contains quite a bit of DHA, making it necessary for that fatty acid to function. (90) The National Eye Institute, part of the National Institutes of Health, concludes that there is “consistent evidence” suggesting long-chain polyunsaturated fatty acids DHA and EPA are necessary for retinal health and may help protect the eyes from disease. (91)
Currently, there isn’t a set standard recommendation for how many omega-3s we need each day, but suggestions range from a fish oil dosage of 500 to 1,000 milligrams daily depending on whom you ask. How easy is it to get these recommended amounts? To give you an idea, there are more than 500 milligrams of total omega-3s in one can of tuna fish and one small serving of wild-caught salmon.
In addition, there was no significant difference in the association of treatment with reduced anxiety symptoms between participants receiving omega-3 PUFAs and those not receiving omega-3 PUFAs in the adolescent subgroup (aged <18 years) (k, 3; Hedges g, 0.020; 95% CI, –0.209 to 0.250; P = .86),48,53,57 in the adult subgroup (aged ≥18 years but <60 years) (k, 11; Hedges g, 0.388; 95% CI, –0.012 to 0.788; P = .06),33,35,36,47,49-51,54-56,59 or in the elderly subgroup (aged ≥60 years) (k, 3; Hedges g, –0.112; 95% CI, –0.406 to 0.181; P = .45).52,58,60 These insignificant results might be due to the smaller sample sizes in each subgroup.
^ Jump up to: a b Casula M, Soranna D, Catapano AL, Corrao G (August 2013). "Long-term effect of high dose omega-3 fatty acid supplementation for secondary prevention of cardiovascular outcomes: A meta-analysis of randomized, placebo controlled trials [corrected]". Atherosclerosis. Supplements. 14 (2): 243–51. doi:10.1016/S1567-5688(13)70005-9. PMID 23958480.
Doses for depression range from less than 1 g/day to 10 g/day, but most studies use doses between 1 and 2 g/day. In my practice, I recommend 1 to 2 g/day of an EPA+DHA combination, with at least 60% EPA, for major depression. I am more cautious in patients with bipolar depression, because the omega-3s may bring on mania, as can most antidepressants. In these individuals, I recommend using omega-3 cautiously, and preferably in combination with a prescription mood stabilizer.
Grigg, L. E., Kay, T. W., Valentine, P. A., Larkins, R., Flower, D. J., Manolas, E. G., O'Dea, K., Sinclair, A. J., Hopper, J. L., and Hunt, D. Determinants of restenosis and lack of effect of dietary supplementation with eicosapentaenoic acid on the incidence of coronary artery restenosis after angioplasty. J Am Coll Cardiol. 3-1-1989;13(3):665-672. View abstract.
Human growth and intellectual development – DHA plays a very important role during fetal development, early infancy and old age. High concentrations of DHA are found in the brain and increase 300 to 500 percent in an infant’s brain during the last trimester of pregnancy. Adding DHA to a pregnant mother’s diet may be beneficial for the fetus’s brain development. Elderly people should also take EPA DHA, because as we get older, our bodies form less EPA and DHA, which may cause less mental focus and cognitive function. Taking EPA DHA also may help with mental abnormalities, such as Alzheimer’s disease and dementia.
Cancer. Research on the effects of fish oil in preventing cancer has produced conflicting results. Some population research suggests that eating fish or having higher blood levels of omega-3 fatty acids from fish oil is linked to a lower risk of different cancers, including oral cancer, pharyngeal cancer, esophageal cancer, colon cancer, rectal cancer, breast cancer, ovarian cancer, and prostate cancer. But other research suggests that eating fish does not reduce the risk of cancer.