Iodine supplementation reduces elevated total‐ and LDL‐cholesterol in iodine‐deficient, overweight women: a randomized, placebo‐controlled trial in Morocco

Abstract

ObjectiveWhether higher serum TSH caused by iodine deficiency adversely affects serum lipids is unknown. Our objective was to determine if correction of iodine deficiency in adults decreases serum TSH and thereby improves the lipid profile. We also measured the effect of iodine repletion on parameters of glucose metabolism and subclinical inflammation.MethodsIn an area of moderate iodine deficiency in Morocco, we randomized overweight women (n=163; mean±SD age 38.6±6.7 y and mean BMI 32.4±4.1 kg/m2) to receive 200 µg iodine daily for 6 months or placebo tablets. At baseline, 3 and 6 months, we measured serum TSH, free T3 and T4, Tg, total, LDL‐ and HDL‐cholestrol, triglycerides, leptin, glucose, insulin, C‐peptide, C‐reactive protein, and urinary iodine concentrations (UIC).ResultsAt baseline, median (95%CI) UIC was 41.6 (37.3, 47.1) µg/L and prevalences of subclinical hypothyroidism, hypothyroxinemia, and hypercholesterolemia were 4, 14.5, and 40.5%, respectively. There were significant time by treatment effects on: UIC and free T4 (higher with treatment; p<0.001), serum TSH and Tg (lower with treatment; p<0.024, p<0.001). Treatment decreased the prevalence of hypercholesterolemia and elevated LDL cholesterol (at 6 months, comparing treatment vs control: 21.5% vs. 34.8% and 35.4% vs. 44.9%; p=0.005, p=0.068)ConclusionsCorrection of iodine deficiency in overweight women decreases serum TSH, reduces hypercholesterolemia and improves the lipid profile. Thus, iodine prophylaxis may help reduce cardiovascular disease risk in populations with high rates of obesity.