New Review Casts Doubts on Benefits of Omega-3s

A recent study contradicted the commonly held belief that enrichment of omega-3 fatty acids in the diet helps prevent both heart disease and cancer.

A simple search of the Internet readily produced information relating to the purported benefits of omega-3 fatty acids. For example, one article stated that men who consumed one or more fish meals--rich in omega-3 fatty acids--per week had a 50% lower risk of developing sudden cardiac death than men who rarely ate fish (less than one fish meal per month). In a separate article, scientists compared blood levels of omega-3 fatty acids in 94 men who died of sudden cardiac death against living men matched for age and smoking habits. They found that high levels of omega-3 fatty acids in the blood were associated with a low risk of cardiac sudden death. Men with the highest blood levels of omega-3 fatty acids had an 80% lower risk of sudden cardiac death than men with the lowest blood levels.

In order to put findings regarding omega-3 fatty acids on a firm scientific base, investigators at the University of East Anglia (Norwich, UK) conducted a systematic review of the professional literature relating to the subject.

Their report published in the March 24, 2006, online edition of the British Medical Journal covered 15,159 titles and abstracts including 48 randomized controlled trials (36,913 participants) and 41 cohort studies.

Surprisingly, the reviewers found little evidence to support the beneficial effects of omega-3 fatty acids. No strong evidence of reduced risk of total mortality or combined cardiovascular events in participants taking additional omega-3 fats was actually reported. When data from a subgroup of studies of long chain omega-3 fats were analyzed separately, total mortality and cardiovascular events were not clearly reduced.

The authors concluded that, "Long chain and shorter chain omega-fats do not have a clear effect on total mortality, combined cardiovascular events, or cancer.” Nonetheless, it will require more high-quality randomized controlled trials of long duration before a final verdict on the benefits of omega-3 fatty acids can be rendered.




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University of East Anglia