Low-salt diet increases insulin resistance in healthy subjects.
Level 2 - randomized trial
Randomized crossover trial in human subjects
PubMed 21036373 · doi:10.1016/j.metabol.2010.09.005
What was done
In a randomized crossover design, 152 healthy men and women (mean age 39.1 ± 12.5 years, BMI 25.3 ± 4.0 kg/m²) were evaluated after consuming a low-salt (LS) diet (target urine sodium <20 mmol/d) for 7 days and a high-salt (HS) diet (target urine sodium >150 mmol/d) for 7 days in random order. Insulin resistance was assessed using the homeostasis model assessment (HOMA) index alongside neurohormonal measurements, comparing unadjusted and multivariable-adjusted models.
What was found
Mean ± SD HOMA index was significantly higher after the LS diet compared with the HS diet (2.8 ± 1.6 vs 2.4 ± 1.7, P < .01). The LS diet also led to higher serum aldosterone (21.0 ± 14.3 vs 3.4 ± 1.5 ng/dL, P < .001), 24-hour urine aldosterone excretion (63.0 ± 34.0 vs 9.5 ± 6.5 µg/d, P < .001), and 24-hour urine norepinephrine excretion (78.0 ± 36.7 vs 67.9 ± 39.8 µg/d, P < .05). The association between the LS diet and higher HOMA index remained statistically significant after adjusting for age, sex, blood pressure, BMI, serum electrolytes, angiotensin II, plasma renin activity, aldosterone, and catecholamines.
Why it matters
These findings show that severe short-term dietary sodium restriction can induce insulin resistance in healthy individuals, highlighting a potential adverse metabolic trade-off associated with extreme sodium restriction.
Limits
The study tested very strict, short-term dietary interventions (7 days each), leaving long-term metabolic effects unknown. Insulin sensitivity was estimated via HOMA index rather than the gold-standard hyperinsulinemic-euglycemic clamp, and the study was conducted exclusively in healthy volunteers, limiting generalizability to populations with hypertension, diabetes, or metabolic syndrome.
Cited by
- contradicts Placing a human subject on a high-salt diet can induce insulin resistance within one week.