Salt restriction: effects on lipids and insulin production in hypertensive patients

The object of the study was to evaluate blood pressure, insulin and glucose metabolism, and serum lipids in hypertensive patients, during 8 weeks on a moderately salt-restricted diet. A double-blind, cross-over study was conducted with hypertensive patients following a moderately salt-restricted diet. Patients were randomised to sodium capsules in one period and placebo capsules during the other period. After a 1-month run-in period, 13 males and three females with mild to moderate essential hypertension (mean age 50 years) complied with a salt-reduced diet. They were randomized to a salt-supplemented group (5 capsules of 10 mmol sodium per capsule) or a salt reduced diet group (5 capsules of placebo) with cross-over after 8 weeks. Serum insulin, insulin C-peptide, and glucose were measured, fasting and 30 min after a 75-g glucose load. Serum lipids and lipoproteins constituting an atherogenic index were measured, along with blood pressure and 24-h urine excretion of sodium and chloride. Non-significant reductions of systolic and diastolic blood pressure (4 mmHg, p = 0.06, and 2 mmHg, p = 0.13, respectively) were observed during the reduced-salt period. The changes observed for fasting insulin, insulin C-peptide, glucose, serum lipids and the atherogenic index were also non-significant. It is concluded that moderate salt restriction seems not to adversely influence insulin resistance or serum lipids in hypertensive patients.