SIOUX FALLS, SOUTH DAKOTA. We have reached a historic point when the American Heart Association actually recommends a supplement for cardio-protection, in this case long-chain omega-3 fatty acids derived from fish oil for those who don't eat enough oily fish. Related to this, research recently published in the American Journal of Cardiologyby Harris, et al report on a study that examined the relationship between a blood marker of omega-3 status and the risk of hospital admission for what is called an acute coronary syndrome (ACS) which translates into a heart attack (MI---myocardial infarction) or severe chest pains (severe angina pectoris).
At issue here is just the incidence of ACS, not the outcome, i.e. no stratification was presented for sudden death from an MI vs. survival or if severe angina was followed by an MI. Mean age for the patients and controls was about 46 years, a group selected because the authors consider this age range to potentially have the highest association between ACS and serum fatty acids. About half were women. In this study, the omega-3 status was determined by a blood test and expressed as the amount of EPA + DHA as a % of total blood fatty acids. The long-chain fatty acids EPA (eicosapentaenoic acid) and DHA (docosahexaenoic acid) are found mostly in oily fish and in fish oil. In this study, relative risk was established by comparison of cases with controls matched for age, race and gender.
When the risk was analyzed in terms of quintiles of omega-3 status (dividing omega-3 status into fifths), a comparison using the lowest level (< 1.2% of total blood fatty acids) as a reference revealed a dramatic drop in risk such that at 1.5-1.8% the risk reduction for ACS was approximately 60% and for > 2.6% is was 80%. This strong protective relationship persisted when the results were corrected for confounding by age, gender, race, body mass index, smoking, diabetes, alcohol consumption, blood lipids and history of an MI or balloon angioplasty. The only significant confounder was, interestingly enough, college education. The authors suggest that those with lower education might have been less able to afford fish and that a college education might be protective against non- omega-3 CHD related risks due to increased health awareness and the ability to follow a healthy lifestyle and as well this group may have had a higher consumption of omega-3 supplements. While high omega-3 status can also favorably influence both triglyceride and high-density lipoprotein (HDL) levels, the authors indicate that in their analysis, the EPA + DHA level was found to be an independent factor in ACS risk. The authors claim that the amounts of omega-3 fatty acids required to achieve cardio-protective blood levels have not yet been established, but intakes of 500-1000 mg/day of EPA + DHA have been suggested and are consistent with the current American Heart Association guidelines. Finally, the authors point out that not all studies provide results that agree with theirs and that answers to important questions must await further trials. They also remark that their study was done in the setting of the U.S. diet.
Harris, W.S. et al. Blood Omega-3 and Trans Fatty acids in Middle-Aged Acute Coronary Syndrome Patients. American Journal of Cardiology, 2007, Vol. 99, pp. 154-8