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

Abstract

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 nonsignificant.

It is concluded that moderate salt restriction seems not to adversely influence insulin resistance or serum lipids in hypertensive patients.

Key Words:

• hypertension
• insulin resistance
• lipids
• sodium-restricted diet