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Omega-3s: From Inuit to Implementation

While the relationship between the omega-3 fatty acids and age related cognition and retinal function have only recently begun to emerge, the cardio-vascular effects of EPA and DHA have been studied for nearly three decades. Interest in these fatty acids from cold water fish began in the late 1970's when studies revealed that Greenland's indigenous Inuits had a significantly lower rate of heart attack compared with Western control subjects. These observations generated an estimated 5000 studies to explore this and other effects of omega-3 fats, and ultimately led to the American Heart Association's recommendations for regular omega-3 consumption in 2002. Research continues to support the cardio-protective role of these fatty acids as evidenced by the findings of several newly published studies.

Fish Fatty Acids More Effective Than Defibrillators

Omega-3 fatty acids may prevent more sudden deaths than automated external defibrillators (AED) in homes and public places or implanted defibrillators according to results of a study supported by the Centers for Disease Control (1). Researchers compared these preventive strategies in a computer-simulated community of 100,000 people that resembled the population of Olmsted County, Minnesota.

Raising the omega-3 fatty acid levels among the cyber-Olmsted citizens resulted in lowering overall mortality rates by 6.4%. In contrast, AEDs reduced death rates by 0.8% and implanted defibrillators (ICDs) lowered the rates by 3.3%. Three-quarters of the reduction in deaths from increased omega-3 levels would come from raising them among the healthy portion of the population.

Raising blood levels of the omega-3 in people after a heart attack could save 58 lives yearly according to the simulation's predictions, while only 7 lives were saved by AEDs and implanted defibrillators prevented 30 deaths yearly. While heart attack survivors are routinely given omega-3 supplements in some European countries, this is generally not the case in the U.S., though the evidence supports it. According to a study published in the September issue of the Journal of the American Board of Family Medicine, only 17% of family doctors were likely to advise patients - including those who had suffered a heart attack - to take omega-3 supplements (2). There is a great need, the authors concluded, to "improve awareness of this important advice."

Heart Benefits Confirmed In Systematic Review

A recently published systematic review of randomized controlled trials, prospective cohort and case-control studies, concludes that the evidence suggests that fish or fish oil supplements reduces the rates of all cause mortality, cardiac and sudden death, and possibly stroke(3). The evidence was stronger for secondary than primary prevention.

Commissioned by the NIH, the review found that increased consumption of EPA and DHA - but not the omega-3 fatty acid alpha linolenic (ALA) - reduces the rates of these CVD outcomes. Data on the effects of ALA, found in flaxseed and other vegetable oils, were reportedly limited and typically of poor quality.

Future Directions: An Omega-3 Index

A second review published online in August ahead of print in the journal Cardiovascular Research, also concludes that the majority of the evidence supports the benefits of omega-3 intake for heart health. The authors, from Saint Luke's Hospital, University of Missouri-Kansas City School of Medicine, have proposed an omega-3 index as a modifiable risk factor for CVD. The Index measures the sum of EPA+DHA in the membrane of erythrocytes as the percent of all fatty acids in the red blood cell membrane. The authors also determined that membrane EPA+DHA index equal to or exceeding 8% is associated with the greatest cardio-protection. In the future, this measure of EPA/DHA status could help physicians tailor advice to their patients to help them achieve levels of omega-3 scientifically reported to provide CVD benefits.

References

1. Kottke TE, et al. Preventing sudden death with n-3 (omega-3) fatty acids and defibrillators. Am J Prev Med 31:316-23, 2006.
2. Oh RC, et al. The fish in secondary prevention of heart disease (FISH) survey-primary care physicians and omega-3 fatty acid prescribing behaviors. J Am Board Fam Med 19:459-67, 2006.
3. Wang C, et al. n-3 Fatty acids from fish or fish-oil supplements, but not alpha-linolenic acid, benefit cardiovascular disease outcomes in primary- and secondary-prevention studies: a systematic review. Am J Clin Nutr 84:5-17, 2006.