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Omega-3 fatty acids may improve coronary health

September 15, 2011

ncreased intake of long-chain polyunsaturated fatty acids http://www.nutri-facts.org/eng/essential-fatty-acids/essential-fatty-acids/ from marine sources may reduce the risk of ischemic heart disease in women, a new Danish study suggests.

In this prospective cohort study spanning more than 23 years, the omega-3 fatty acid intake of 3277 Danish women and men free of known ischemic heart disease (IHD) was observed (1). During the study, 471 cases of IHD were documented. An analysis showed that high intake of long-chain omega-3 eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA) – 0.45 to 11.2 grams per day – was associated with a 38% reduction in the risk of IHD in women only. High intake of alpha-linolenic acid (ALA) – with a median daily intake of 1.2 g/d to 1.6 g/d – and intake of omega-6 fatty acid linoleic acid (LA) did not significantly decrease the risk of IHD among men or women. However, there was no statistically significant trend showing a reduced risk of IHD in men with increased ALA intake.

The researchers concluded that only a higher intake of long-chain omega-3 fatty acids such as EPA and DHA – not ALA or LA – may reduce the risk of ischemic heart disease in women. EPA and DHA are common in fish and in fish oil supplements, while ALA and LA come from plants. They noted, however, that about one-half of the study population was under the estimated minimum requirement of ALA (about 1.2 g/d in adults). Further larger studies would be necessary to examine the potential effect modification of different omega-3 fatty acids.

Past studies indicated that the conversion rate of ALA to the longer chain EPA is very small. It has been reported that in humans only between 8 and 20 percent of ALA is converted to EPA, while between 0.5 and
9 percent of ALA is converted to DHA. In addition, gender seems to play an important role among women of reproductive age, reportedly converting ALA to EPA at a 2.5-fold greater rate than healthy men. Moreover, the conversion could also affected by the existing levels of EPA and DHA in the body.

References

  1. Vedtofte M. S. et al. Dietary a-linolenic acid, linoleic acid, and n–3 long-chain PUFA and risk of ischemic heart disease. American Journal of Clinical Nutrition. Online publication, August 2011