May/June 2014

Omega-3 Supplementation

By Linda Antinoro, JD, RD, LDN, CDE
Today’s Geriatric Medicine
Vol. 7 No. 3 P. 30

Despite recently published reports suggesting that omega-3 supplements lack the cardiovascular health benefits they once claimed and could be associated with various health risks, many older adults continue to use them. According to the 2014 ConsumerLab.com survey of 10,000 supplement users, fish/marine oil supplements remain popular, with 67.2% of respondents using them.

This consumption may not be ill advised. Research on omega-3s suggests that these supplements may be useful for people with very high triglyceride levels and individuals who have difficulty eating oily fish twice per week.

Cardiovascular Connection
Previous clinical trials of fish oil supplements have associated omega-3 supplementation with heart health benefits. The GISSI Prevenzione study, for example, published in the August 1999 issue of the Lancet, followed 1,324 patients and found that the participants in the group that received a 1-g dose of an omega-3 supplement each day for 3 1/2 years had a significant reduction in their risk of death, nonfatal myocardial infarction, and nonfatal stroke among those who had survived a recent myocardial infarction.1

However, a 2013 study involving more than 12,000 patients at high risk of a heart attack who were randomized to receive either 1,000 mg of fish oil per day or a placebo showed no reduction in cardiovascular mortality and morbidity after five years.2

A meta-analysis of 20 studies published in the September 2012 issue of The Journal of the American Medical Association supports a similar conclusion. Patients who received an average dose of 1.51 g of omega-3 supplements per day for a median treatment duration of two years didn’t experience a lower risk of myocardial infarction, stroke, cardiac death, sudden death, or all-cause mortality.3 However, Dariush Mozaffarian, MD, DrPH, a cardiologist and epidemiologist at Harvard Medical School, points out that other research found that omega-3s lowered the risk of cardiac death by 10%.

According to researchers, a possible reason for the seemingly contradictory results between the earlier and more recent studies on omega-3 supplementation is that most of the later trials involved people with established heart disease who already were being treated with medications such as antihypertensives, antiarrhythmics, and statins.4 For example, in the GISSI trial, only 5% of patients received statins at baseline. Patients already using cardioprotective agents may not experience further benefits from omega-3 supplements because drug therapy can mimic or mask the actions of omega-3 supplements by lowering blood pressure, blood lipid levels, or inflammation.4

Plus, it’s currently unknown whether omega-3 supplements will help to thwart cardiac problems in healthy individuals or in those at low risk of heart disease. The Vitamin D and Omega-3 Trial (VITAL), an ongoing study of 20,000 men and women that’s investigating whether taking daily supplements of vitamin D3 (2,000 IU) or omega-3s (1 g) lowers the risk of developing cancer, heart disease, and stroke in people who don’t have a prior history of these illnesses, expects to answer this question.

One consistent benefit demonstrated by research on omega-3 supplements is their ability to improve hypertriglyceridemia. The American Heart Association endorses patients taking between 2 and 4 g of EPA and DHA per day in capsule form under a physician’s supervision for individuals who need to lower triglyceride levels. Even modest doses work to some degree. In one study, triglyceride levels dropped 14.5 mg/dL more in patients who took a 1-g capsule containing 465 mg of EPA and 375 mg of DHA compared with those who received a placebo.5 Though triglyceride reduction didn’t decrease the rate of cardiovascular events in this study, lowering triglycerides remains a worthwhile goal because extremely elevated triglycerides can contribute to pancreatitis.4

Prostate Cancer
A study published in the August 2013 issue of the Journal of the National Cancer Institute examined the association between blood levels of omega-3 fatty acids and prostate cancer risk among men who participated in the Selenium and Vitamin E Cancer Prevention Trial (SELECT). The researchers found that men who had higher blood levels of omega-3 fatty acids were more likely to develop prostate cancer.6 Many headlines followed, erroneously singling out fish oil supplements as the culprit.

According to Theodore Brasky, PhD, lead researcher of the study, “Only a minority of the men in the study took supplements.” While researchers saw a correlation and not a cause-and-effect relationship, it may be prudent for men to avoid large doses of omega-3s whether from excessive fatty fish intake or supplements, he says.

Conversely, a study published in the January issue of Cancer Prevention Research found that men with prostate cancer who ate a low-fat diet and took fish oil supplements had lower levels of serum proinflammatory eicosanoids and a lower cell cycle progression score (a measurement used to predict cancer recurrence) than men who ate a typical Western diet.7 Subjects received 5 g of fish oil per day consisting of five 1-g capsules with each containing 200 mg of EPA and 367 mg of DHA.

The researchers acknowledge that they couldn’t determine whether either treatment alone would have produced the same results. They combined the two interventions based on preclinical trials that showed a decrease in the development and progression of prostate cancer associated with reducing the ratio of omega-6 to omega-3 fatty acids and lowering dietary fat intake.

Optimal Omega-3 Doses
Most medical experts and health organizations recommend that patients receive 250 to 500 mg of EPA and DHA per day, first from fatty fish and then from supplements. According to the 2010 Dietary Guidelines, the mean intake of seafood in the United States is approximately 3 1/2 oz per week. Increasing intake to 8 oz per week provides an average consumption of 250 mg of EPA and DHA per day.

The American Heart Association endorses this recommendation for healthy individuals who have no documented coronary heart disease (CHD), although it acknowledges that patients with CHD probably need closer to 1 g of EPA and DHA combined per day, and that this amount may require the addition of omega-3 supplementation. The association discourages exceeding 3 g/day from capsules without the supervision of a physician or other health care professional.

Bottom Line
In counseling patients about omega-3 intake, inform them that consumption is important because the body can’t make these essential fatty acids on its own. Patients should obtain omega-3s first through food whenever possible. While plant-based omega-3s such as walnuts, chia seeds, and ground flax have alpha-linolenic acid and other nutritional merits, the body converts alpha-linolenic acid into EPA and DHA at rather low levels.

For patients who have difficulty consuming enough omega-3s, provide guidance based on their health status to determine the correct dosage of omega-3 supplements they should take daily.

— Linda Antinoro, JD, RD, LDN, CDE, is a freelance writer and part of the Nutrition Consultation Service at Brigham and Women’s Hospital in Boston.

References
1. GISSI-Prevenzione Investigators (Gruppo Italiano per lo Studio della Sopravvivenza nell’Infarto Miocardico). Dietary supplementation with n-3 polyunsaturated fatty acids and vitamin E after myocardial infarction: results of the GISSI-Prevenzione trial. Lancet. 1999;354(9177):447-455.

2. Risk and Prevention Study Collaborative Group. n-3 fatty acids in patients with multiple cardiovascular risk factors. N Engl J Med. 2013;368(19):1800-1808.

3. Rizos EC, Ntzani EE, Bika E, Kostapanos MS, Elisaf MS. Association between omega-3 fatty acid supplementation and risk of major cardiovascular disease events. A systematic review and meta-analysis. JAMA. 2012;308(10):1024-1033.

4. Kwak SM, Myung SK, Lee YU, Seo HG. Efficacy of omega-3 fatty acid supplements (eicosapentaenoic acid and docosahexaenoic acid) in the secondary prevention of cardiovascular disease: a meta-analysis of randomized, double-blind, placebo-controlled trials. Arch Intern Med. 2012;172(9):686-694.

5. Origin Trial Investigators, Bosch J, Gerstein HC, et al. n-3 fatty acids and cardiovascular outcomes in patients with dysglycemia. N Engl J Med. 2012;367(4):309-318.

6. Brasky TM, Darke AK, Song X, et al. Plasma phospholipid fatty acids and prostate cancer risk in the SELECT Trial. J Natl Cancer Inst. 2013;105(15):1132-1141.