Abstract

Obesity, type 2 diabetes and insulin resistance are highly prevalent, and these conditions are strongly related to disorders of lipid metabolism characterized by increased tissue/cellular lipid accumulation, particularly in skeletal muscle. Recent evidence shows that specific fatty acids affect cell metabolism, modifying the balance between fatty acid oxidation and lipogenesis. Thus, it has been hypothesized that changes in dietary fatty acid composition can modify insulin resistance. Animal studies provide support for this notion. In humans, intake of dietary saturated and n-6 polyunsaturated fatty acids have increased, while n-3 fatty acid intake has decreased, which strengthens the need for assessing the influence of the specific type of fatty acid on insulin action. This review specifically examines the evidence relating saturated fat with insulin resistance in humans. Most of the available evidence does not show increased insulin resistance after consuming a saturated fat diet versus an unsaturated fat diet. However, a well-powered and well-designed study found that consumption of saturated fat increased insulin resistance by 10% when compared with a high-monounsaturated fat diet. Modifications in dietary fatty acid composition may have implications in addressing the present epidemic of nutrition-related chronic disease. © CAB International 2009.