Plasma cholesteryl ester fatty acid composition, insulin sensitivity, the menopause and hormone replacement therapy

This study was designed to determine the effect of menopause and hormone re placement therapy (HRT) on plasma cholesteryl ester fatty acid (CEFA) compo sition and insulin sensitivity and the relationships between these variable s in perimenopausal women (aged 40-55 years) including 49 who were premenop ausal and 32 who were postmenopausal. Plasma cholesteryl ester proportions of dihomo-gamma-linolenic acid (20:3 n-6) were correlated significantly wit h insulin sensitivity index (r = -0.319, P = 0.005), fasting serum insulin levels (r = 0.230, P = 0.038), body mass index (r = 0.242, P = 0.03) and pe r cent body fat (r = 0.329, P = 0.003) in perimenopausal women (n = 81). Si milar associations were observed in premenopausal women. Regression analysi s suggested the relationships between 20:3 n-6 proportions and indices of i nsulin action may be partly mediated by levels adiposity. In postmenopausal women, 6 months of HRT significantly (P = 0.008) increased the ratio of ar achidonic acid (20:4 n-6) to Linoleic acid (18:2 n-6), which is an indicato r of activity in the pathway of 20:4 n-6 synthesis, compared with placebo. These findings suggest that the type of fat in the diet indicated by plasma CEFA composition is linked to adiposity and insulin action. They also sugg est that in postmenopausal women, HRT may increase the synthesis of 20:4 n- 6, which is the precursor for eicosanoids with important cardiovascular fun ctions.