Replacing Saturated Fats with Polyunsaturated Fats Best Bet for Heart

Background Coronary heart disease (CHD) is the leading cause of death in the United States, and a first-line approach for decreasing its risk is lowering saturated fatty acid (SFA) intake. However, whether dietary SFAs should be replaced with unsaturated fatty acids or carbohydrates remains an area of active debate. Further, sex and age may influence the relation between SFAs and CHD, and it is difficult to measure precisely what free-living people really eat. These factors, therefore, need to be accounted for, and this necessitates the use of a very large number of individuals in studies related to this topic. To meet this challenge, a multinational group of nutrition researchers pooled data from several previously conducted human studies to investigate the effect of replacing SFAs with unsaturated fatty acids or carbohydrates to prevent CHD. Their results are published in the May 2009 issue of The American Journal of Clinical Nutrition. Accompanying their article is a discerning editorial by Katan.

Study Design Data from 11 American and European cohort studies were used to investigate associations between a lower energy intake from SFAs and a concomitant higher energy intake from monounsaturated fatty acids (MUFAs), polyunsaturated fatty acids (PUFAs), or carbohydrates on risk of CHD events. The final population consisted of 344,696 middle-aged and older women and men. Factors, such as sex and age, known to be important risk factors for CHD were controlled for in the analyses.

Results These data indicated that, for a 5% lower energy intake from SFAs and a concomitant 5% higher energy intake from PUFAs, one might expect a 13% lower risk of coronary events and a 26% lower risk of coronary deaths. Conversely, for a 5% lower energy intake from SFAs and a concomitant 5% higher energy intake from carbohydrates, one might expect a modestly higher risk of coronary events. These relations were not influenced by sex or age.

Conclusions Results from this large, epidemiologic study suggest that replacing SFAs with PUFAs rather than MUFAs or carbohydrates may provide the best macronutrient mix for preventing CHD. In his companion editorial, Katan compares the effect of PUFA intake in this study with metabolic trials on PUFA consumption and blood lipids and the scattered clinical trials on PUFA intake and CHD. He concludes that the 3 lines of research provide remarkably consistent results. He also reminds us that data and conclusions obtained from cell culture and animal studies might not always be relevant to humans. For example, although animal and in vitro studies have suggested that increasing PUFA intake might increase risk of CHD, the human data refute this hypothesis.

Lähde: AJCN Research Highlights, May 2009