Dietary lipids: an additional regulator of plasma levels of sex hormone binding globulin.

The effect of dietary lipid consumption on plasma levels of sex-hormone binding globulin (SHBG), free testosterone and cholesterol was studied in 6 normal men. After consuming a diet with a high fat content (greater than 100 g fat/day) for two weeks, the mean plasma cholesterol level increased (p less than 0.02) while the mean SHBG level decreased (p less than 0.02). Changing the diet from one with a high fat to low fat content (less than 20 g fat/day) for a further two week period resulted in a significant reduction in mean plasma cholesterol level (p less than 0.001) while the mean SHBG level increased (p less than 0.01). The increase in plasma SHBG was associated with a significant decrease in the free testosterone fraction and free testosterone concentration. No significant changes were detected in plasma samples obtained from the same men during a control period. The results from this study demonstrate that dietary lipid intake is an additional factor involved in the regulation of plasma levels of SHBG.