Endocrine Abstracts

Background: There is evidence that dietary interventions can reduce antibody levels in patients with autoimmune thyroid disease (ATD), which can have a beneficial effect on the clinical manifestations of the disease. The aim of this study was to review the literature regarding the different types of dietary supplementations and their effectiveness in the management of ATDs.

Methods: Using a predefined search strategy, four databases were searched (PubMed, Web of Science, CINAHL and Cochrane central register of clinical trials). Efficacy was assessed from randomized controlled trials and cluster randomized controlled trials including post-intervention mean, standard deviation and sample sizes for both the intervention and control group to calculate pooled effect sizes. Outcomes evaluated included serum levels of TSH, FT3 and FT4, levels of antibodies and change from baseline in symptoms of ATD. Risk of bias was assessed using the Cochrane tool for assessment of risk of bias.

Results: Twenty eight studies were included in the analyses, focusing on ATD (n = 9), Graves’ disease (n = 8), Hashimoto thyroiditis (n = 7), postpartum thyroiditis (n = 3)and a prevention trial (n = 1).Treatments included supplementation with Selenium (n = 15), Vitamin C (n = 1), Nigella sativa (n = 1), a combination of carotene, vitamin C, Vitamin E and Selenium (n = 2), Vitamin D (n = 4), anatabine lozenges (n = 1) and Myo-inositol plus L-selenomethionine (n = 1).

Selenium supplementation improved serum TSH levels –0.48 (95% CI : –0.87 to –0.03); anti-TPO antibody –1.056 (–1.76 to –0.35); and FT4 levels –0.259 (95% CI : –0.57 to 0.05). Improvement across other outcomes was not significant. Nigella Sativa supplementation also showed an improvement in TSH –0.77 (95% CI : –1.41 to –0.13) and FT4 levels 0.67 (95% CI : 0.04 to 1.31). Myoinositol and selenium combination revealed improvement in FT4 0.54 (95% CI : 0.24 to 0.85) and Anti Tg antibody levels –0.52 (955 CI : –0.83 to –0.21). Iodine supplementation yielded a statistical significance only for anti TR antibodies –0.76 (95% CI : –0.96 to –0.56). Use of Vitamin A improved Anti Tg antibody levels 0.46 (95% CI : 0.13 to 0.79). Vitamin C and D supplementation revealed no significant effect on outcomes.

Conclusion: Dietary interventions were found to have a limited role in the management of ATDs. The evidence was generally of poor quality. We recommend that higher quality trials be conducted in the future to build a solid evidence base for use of supplements in autoimmune thyroid conditions.