Moderate dietary salt restriction does not alter insulin resistance or serum lipids in normal men

Dietary salt restriction lowers blood pressure and has been advocated as a population-based strategy to reduce the cardiovascular morbidity associated with hypertension. However, the effect of lowering salt intake on metabolic vascular risk factors such as insulin resistance and levels of atherogenic lipids and fasting insulin is uncertain. We have studied the short-term effect of moderate dietary salt restriction on insulin resistance and serum lipids in 34 nonobese (body mass index [mean +/- SD] 23.4 +/- 1.8 kg/m2), normotensive young white men. Subjects were maintained on a low salt diet ( < 80 mmol/day) for the 2-week study period. In a randomized, cross-over, double-blind fashion, each subject also received 120 mmol of sodium chloride per day during one of the study weeks, and a matching placebo during the other. Insulin resistance, serum insulin, lipids, and blood pressure were measured in the fasting state at the end of each study week. Urinary sodium excretion (185 +/- 46 v 52 +/- 25 mmol/day, P < .001), serum sodium (141.2 +/- 1.2 v 140.1 +/- 1.3 mmol/L, P < .001) and body weight (75.4 +/- 9.1 v 75.0 +/- 9.3 kg, P < .05) were higher during the high salt than the low salt period. Serum creatinine was higher during the low salt period (100 +/- 8 v 90 +/- 9 mumols/L, P < .01). There was no difference in blood pressure, insulin resistance, serum insulin, C-peptide, total cholesterol, low density lipoprotein cholesterol, high density lipoprotein cholesterol or its subfractions, triglycerides, apolipoprotein A1, or apolipoprotein B between the high salt and low salt periods. We conclude that short-term, moderate dietary salt restriction does not adversely affect insulin sensitivity or levels of atherogenic lipids in normotensive nonobese men.