Effects of bee propolis on thyroid function tests in healthy volunteers

Purpose: The current study investigates the effects of bee propolis as a dietary supplement on thyroid function in healthy individuals. Methods: Sixty-nine apparently healthy subjects of both genders aged between 25 and 45 years and had a body mass index in the range of 18.5-25 kg m-2 were enrolled in the study. The participants were divided into two groups, 34 volunteers treated with 1 gram of bee propolis daily and the other 35 were on placebo pills for 2 months. Total triiodothyronine (TT3), total thyroxine (TT4) and ultra-sensitive thyroid stimulating hormone (USTSH) were measured in the two groups before and after treatment to assess thyroid function. Results: The results showed a significant increase in body weight (from 73.4 ± 7.2 to 74.8 ± 7.5 kg, p < 0.05) and BMI (from 24.2 ± 1.2 to 24.7 ± 1.5 kg m-2 , p < 0.05) with significantly decreased TT3 (from 2.17 ± 0.07 to 1.87 ± 0.09 nmol/L, p < 0.01) in bee propolis-treated group, whereas TT4 and USTSH showed non-significant changes. Conclusion: The results reveal a significant association of bee propolis supplementation with reduced TT3 levels in healthy subjects. The link may assist clinicians in monitoring the safety of bee propolis supplementation.