Individual fatty acids in cardiometabolic disease
Since the formulation of the diet-heart hypothesis, fatty acids have been implicated in the etiology of cardiometabolic diseases and have been studied extensively. Early metabolic ward studies reported that replacement of dietary calories from saturated fat with polyunsaturated fat leads to small, but important, reductions in low-density lipoprotein cholesterol concentrations as well as improved insulin action. Subsequent evidence from epidemiological studies indicated positive associations for diets high in saturated fats and inverse associations for diets high in unsaturated fats with coronary risk. As a consequence of this evidence, current nutritional guidelines encourage reduced consumption of total saturated fats, increased consumption of polyunsaturated fats from fish oil or plant sources, and avoidance of artificial trans fats. Nonetheless, current guidelines provide divergent recommendations about individual fatty acid subtypes, potentially reflecting uncertainties surrounding the specific associations of these fatty acids subtypes with cardiometabolic outcomes. This is of particular significance as different subtypes and isomers of fatty acids may have diverse biological and health effects, and the overall balance between various individual fats may be more important than any composite fatty acid family alone. This chapter provides a broad discussion to summarize the biology, determinants, and key epidemiologic evidence of total and individual fatty acids in relationship with coronary heart disease and diabetes risk.