Salt intake and insulin sensitivity in healthy human volunteers.
Level 2 - randomized trial
Randomized crossover trial testing dietary salt interventions against physiological outcomes
PubMed 17425514 · doi:10.1042/CS20060361
What was done
Healthy, normotensive, lean volunteers completed a crossover dietary intervention comprising 6 days of a low-salt diet (20 mmol sodium daily) and subsequently 6 days of a high-salt diet (200 mmol sodium daily). After each period, participants underwent a euglycaemic clamp. Investigators measured insulin-mediated glucose disposal, calf blood flow before and during insulin infusion, plasma non-esterified fatty acids, renin concentration, aldosterone activity, and plasma noradrenaline concentration.
What was found
Insulin-mediated glucose disposal during euglycaemic clamp conditions was significantly higher following the high-salt diet than the low-salt diet (7.41 +/- 0.41 vs 6.11 +/- 0.40 mg x kg(-1) x min(-1); P = 0.03). No significant changes were detected in calf blood flow or plasma non-esterified fatty acids between interventions. The low-salt diet led to expected increases in renin concentration, a 4-5-fold increase in serum aldosterone, and a significantly greater increase in plasma noradrenaline during insulin infusion compared to the high-salt diet.
Why it matters
This study indicates that short-term low sodium intake reduces insulin sensitivity in healthy lean individuals, likely mediated by compensatory neurohormonal activation including elevated aldosterone and sympathetic activity.
Limits
The abstract does not state the sample size (n) or participant demographics beyond healthy lean status. The dietary interventions were short (6 days each), tested extreme dietary extremes (20 vs 200 mmol sodium daily), and findings may not generalize to individuals with hypertension, diabetes, or over longer durations.
Cited by
- contradicts Placing a human subject on a high-salt diet can induce insulin resistance within one week.