Fatty Acids: Friends or Foe? Relation Between Dietary Fat and Insulin Sensitivity

A high dietary fat intake is associated with an increased risk for the development of obesity. Obesity, in a particular abdominal obesity, is one of the major risk factors for the development of insulin resistance and type 2 diabetes mellitus. There are indications for a direct relation between dietary fat and insulin sensitivity, independent of body weight, which may be mainly mediated by dietary fat quality. Cross sectional studies in humans show a clear relationship between dietary fat quality and markers of insulin sensitivity. Also, the composition of fatty acids in serum lipids and tissues (muscle, adipose tissue), partly reflecting dietary fatty acid intake, show that insulin resistance is related to a specific pattern of fatty acids with a high content of SFAs (mainly palmitic acid) and a low concentration of PUFAs (mainly n-3 and n-6 PUFAs). There is increased evidence that lipid overflow to non-adipose tissues (lipotoxicity) may interfer with insulinmediated glucose uptake through an accumulaton of intramyocellar lipids. PUFAs may regulate fuel partitioning within the muscle cell through effects on membrane phospholipid composition and intramuscular fat storage mediated by changes in membrane fluidity, intracellular signaling molecules and gene expression. The relationship between dietary fat and insulin sensitivity needs additional confirmation in well-controlled human dietary intervention trials