Responses of plasma lipoproteins and sex hormones to the consumption of lean fish incorporated in a prudent-type diet in normolipidemic men

Objective: The effects of lean fish on plasma lipoproteins. postheparin pla sma lipolytic activities and sex hormones were examined in 11 normolipidemi c male subjects. Methods: This study was a randomized crossover trial of two isoenergetic pr udent-type diets, lean fish diet and beef, pork, veal, eggs and milk (nonfi sh) diet. Experimental diets provided approximately 11800 kJ-18% as protein s, 50% as carbohydrates, 32% as lipids [ratio of polyunsaturated to saturat ed fatty acids (P:S) of 1:1 compared with 0.5:1 in preexperimental diet], a nd 260 mg cholesterol/day. Results: Compared with the nonfish diet, the lean fish diet induced higher plasma total and LDL apolipoprotein (apo) B and apo B:apo A-1 ratio, indica ting that the substitution of lean fish for beef, veal, pork, eggs and milk provides little benefits with regard to plasma apo B concentrations in a l ow-fat high P:S diet. Moreover, triglycerides:apo B and cholesterol:apo B r atios of VLDL were lower following the lean fish diet than the nonfish diet , suggesting the presence of smaller very low-density lipoprotein (VLDL) pa rticles following the consumption of lean fish. Higher plasma concentration s of sex hormone-binding globulin (SHBG), HDL2 cholesterol and HDL,:HDL, ch olesterol ratio were found with the lean fish diet compared with the nonfis h diet. Negative correlations between plasma postheparin lipoprotein lipase (LPL) activity and VLDL triglycerides (n = 11, r = -0.53, p = 0.02), and b etween plasma postheparin LPL activity and VLDL triglycerides:apo B ratio ( n = 11, r = -0.64, p = 0.02) were also observed following the lean fish die t. Conclusion: These results suggest that the effects of substituting lean fis h for beef, veal, pork, eggs and milk on plasma lipoproteins may be partly associated with variations in plasma sex hormone status and plasma LPL acti vity in normolipidemic men.