The Effect of Some Micronutrients Multi-Supplementation on Thyroid Function, Metabolic Features and Quality of Life in Patients Treating With Levothyroxine and Vitamin D: A Double-blind, Randomized Controlled Trial.

Background: It has been reported that reducing inflammatory damage and providing essential nutrients can improve thyroid function. Although sufficient clinical evidence does not support the routine prescription of nutritional supplements except for vitamin D therapy, as part of hypothyroidism treatment. We aimed to investigate the effects of supplementation with certain micronutrients known as essential for normal thyroid function on thyroid function, metabolic manifestations, and quality of life in patients with hypothyroidism.

Methods: In the current randomized controlled trial, we randomly assigned 104 patients with hypothyroidism receiving levothyroxine and vitamin D to either supplementation with 200 µg selenium, 15 mg zinc, 250 mg magnesium, 2500 IU vitamin A, 120 mg vitamin C, and 100 IU vitamin E per day (LT4VDS group) or placebos (LT4VDP group) for 8 weeks. Serum thyroid-stimulating hormone (TSH), free thyroxine (fT4), anti-thyroid peroxidase antibody (TPO-Ab), triglyceride (TG), total cholesterol (TC), low-density lipoprotein (LDL-c), high-density lipoprotein (HDL-c), fasting blood sugar (FBS), fasting insulin, homeostatic model assessment for insulin resistance (HOMA-IR), C-reactive protein (CRP), as well as blood pressure, and anthropometric values, were measured before and after intervention. The 36-item short-form survey, the International Physical Activity Questionnaire, and 2 food recalls were completed. Thyroid function test, metabolic factors, and quality of life indices were compared between the 2 groups after the intervention, using analysis of covariance tests, with robust standard errors and intention to treat analysis, "multiple imputation method," adjusted for covariates.

Results: In the LT4VDP group, higher postintervention values of FBS (98.5 [85.7, 106.5] in LT4VDP group vs 89 [82.5, 95.7] in LT4VDS group; P = 0.012; effect size, 0.083), and HOMA-IR (2.1 [1.3, 3.8] in LT4VDP group vs 1.6 [1.1, 2.4] in LT4VDS group; P = 0.031; effect size, 0.053) were observed. Intention to treat analysis (n = 95 participants) showed similar results regarding FBS. In the LT4VDP group, a marginal increase regarding CRP (Δ: 1 [-1, 1] in LT4VDP group vs -0.6 [-1, 1] in LT4VDS group; P = 0.051), and Insulin (Δ: 2.9 [0.4, 6.1] in LT4VDP group vs 1 [-0.5, 2.3] in LT4VDS group; P = 0.042) were observed, whereas in the LT4VDS group the physical quality of life partially improved (Δ: 0.2 [9.1] in LT4VDP group vs 3.6 [6.3] in LT4VDS group; P = 0.044, effect size, 0.012). Between-group comparison of difference values did not show significant results regarding other outcomes, including TSH, fT4, TPO-Ab, mental quality of life, TG, TC, LDL, HDL, and blood pressure.

Conclusion: An 8-week supplementation with the nutrients above may affect insulin resistance and quality of life in patients with hypothyroidism; additional clinical trials are recommended.