• The Effects of Synbiotic Supplementation on Thyroid Function in Hypothyroid Patients: A Randomized, Double‑Blind, Placebo‑Controlled Trial
  • Sepide Talebi,1,* Gholamreza Askari,2 Mozhgan Karimifar ,3 Zahra Heidari ,4 Hamed Mohammadi ,5
    1. Student Research Committee, Department of Community Nutrition, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran
    2. Food Security Research Center and Department of Community Nutrition, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran
    3. Endocrine & Metabolism Research Center, Isfahan University of Medical Sciences, Isfahan, Iran
    4. Department of Biostatistics and Epidemiology, School of Health, Isfahan University of Medical Sciences, Isfahan, Iran
    5. Student Research Committee, Department of Clinical Nutrition, School of Nutrition and Food Science, Isfahan University of Medical Sciences, Isfahan, Iran


  • Introduction: : Hypothyroid disease, which is a major endocrine problem worldwide, characterized by impaired production of thyroid hormones. There is a positive link between thyroid homeostasis and the composition of gut microbiota. A limited number of studies have suggested the efficacy of probiotic products on levothyroxine metabolism and thyroid hormone activity. Therefore, the purpose of this study was to investigate the effect of synbiotic supplementation on thyroid function in subjects with hypothyroidism.
  • Methods: This study was conducted as a randomized, double-blind, placebo-controlled trial involving 60 patients with hypothyroidism. Participants were randomly recruited into two groups to receive either 500 mg/d of synbiotic (n=30) or a placebo (n=30) for 8 weeks. Thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), anti–thyroid peroxidase (Anti-TPO), levothyroxine dose (LT4 dose) were assessed at first and the end of intervention.
  • Results: A total of 60 patients with hypothyroidism (5 males and 55 females) were enrolled at the beginning of this study. Finally, only 56 patients (29 in synbiotic and 27 in placebo groups) completed to the final analysis. Our findings presented, TSH concentration, and levothyroxine dose were significantly decreased after the 8-week intervention in the synbiotic group (P< 0.05), while there were no significant differences seen in the placebo group. In addition, FT3 at the end of intervention was significantly higher (P = 0.001) in both groups, although these changes were not significant between the two groups (P = 0.259). Moreover, no statistical significance was observed within or between groups in serum anti-thyroid peroxidase (P > 0.05).
  • Conclusion: We found taking synbiotic among hypothyroid patients for 8 weeks had beneficial effects on thyroid function in within group analysis, whereas did not have any effects on all variables in comparison to the placebo. Further studies with larger sample size and longer duration are needed to confirm this effect.
  • Keywords: Synbiotic, Thyroid function, Hypothyroidism