Fatty acids and insulin sensitivity

Purpose of review Given the pathophysiological importance of insulin resistance, the potential impact of dietary fatty acids is highly relevant. The effects of different types of dietary fatty acids on insulin sensitivity in humans are discussed, with focus on recent controlled studies. Recent findings Observational studies assessing fatty acid composition in serum or tissues suggest that insulin resistance is associated with relatively high intakes of saturated fat (e.g. palmitic acid) and low intakes of polyunsaturated fat (e.g. linoleic acid), findings that are supported by recent clinical data. Most controlled studies have hitherto examined the effect of monounsaturated fat on insulin sensitivity, several indicating that it has beneficial effects when substituted for saturated fat. More clinical data comparing n-6 polyunsaturated, monounsaturated and saturated fat are needed to identify the optimal dietary fat composition, especially in patients with insulin resistance/obesity and diabetes. The total fat content of the background diet should also be considered in future studies. Finally, we and others hypothesize that dietary fatty acids may partly mediate their effects on insulin action by regulating the activity of lipogenic enzymes and desaturases. Summary Substituting saturated fat with unsaturated fat seems to have beneficial effects on insulin sensitivity, although the clinical significance of modifying fat quality alone is still unclear.