Dietary fat, fatty acid composition in plasma and the metabolic syndrome

Abstract

The metabolic syndrome, a cluster of disorders often including abdominal obesity, is associated with a high risk of cardiovascular disease and premature death. Insulin resistance is a key feature of the metabolic syndrome. Observational studies have indicated that the type of fat in the diet may be related to the development of insulin resistance and the metabolic syndrome, also independent of possible effects on body weight. Dietary surveys are often imprecise. One way to monitor the type of fat in the diet is to record the fatty acid composition in plasma. This review summarizes recent data on the relationships between fatty acid composition in plasma and insulin resistance, diabetes and other disorders related to the metabolic syndrome. Insulin resistance and insulin resistant states are often associated with the fatty acid pattern in plasma, characterized by an increased proportion of palmitic (16 : 0) and a low proportion of linoleic (18 : 2 n-6) acids, with a distribution of other fatty acids indicating an increased activity of delta-9 and delta-6 desaturase. This shows that there may be a causal relationship between the type of fat in the diet and insulin action, an assumption supported by recent dietary intervention studies. In a public health perspective these results, from both observational and intervention studies, underline the importance of fat quality in the diet for the development of a number of prevalent diseases. Taken together with several earlier studies and recent epidemiological findings, they give strong support to present dietary guidelines.