Written by Greg Arnold, DC, CSCS. In this 12-week study of 68 obese female adults with hypothyroidism, those who supplemented with zinc or a zinc-selenium combination had a significant improvement in thyroid hormones (free T3 and T4); however, additional tests are needed to determine if a combination of selenium-zinc or zinc alone are effective in preventing thyroid dysfunction.
Hypothyroidism is when the thyroid gland, located in the front of the neck surrounding the windpipe, does not produce enough hormones. This can slow down the metabolism, frequently leading to weight gain, fatigue, lethargy, even constipation and decreased quality of life (1). About 1 in 22 Americans over the age of 12 (4.6%) suffer from hypothyroidism (2).
Now a new study (3) suggests either supplementation with zinc or zinc and selenium may improve thyroid health. The study involved 68 females aged 25 to 65 with a body mass index between 25 and 40 kg/m2 and diagnosed with hypothyroidism. They received one of the following per day for 12 weeks:
- 30 milligrams zinc (as zinc gluconate) and 200 micrograms selenium (as selenium yeast)
- 30 mg zinc
- 200 micrograms selenium
- Placebo (control group)
Blood samples were obtained before and after the study to measure for thyroid function. Each woman also completed a 24-hour recall questionnaire and completed a physical activity questionnaire (4).
After 12 weeks, researchers noted three significant thyroid-related improvements in the groups:
- The first improvement was a 9.2% increase levels of a thyroid hormone called “Free T3” in the zinc-selenium group (4.13 to 4.51 picomoles/Liter, p = 0.017) and a 27% increase in the zinc-only group (4.06 to 5.16 pmol/l, p = 0.004).
- The second improvement regarded another thyroid hormone, “Free T4”, with a 12.4% increase in the zinc-selenium group (17.97 to 20.20 pmol/l, p = 0.025).
- Finally, the ratio between Free T3 and Free T4 improved by 23.8% increase in the zinc-only group (0.21 to 0.26, p = 0.044).
No significant differences were seen in body mass index in any of the groups.
Citing research showing zinc to be “necessary for biological activity of Free T3 and Free T4 (5), the researchers concluded that “This study showed some evidence of an effect of zinc alone or in combination with selenium on thyroid function of overweight or obese female hypothyroid patients” and that “Similar clinical trials are required to examine the effectiveness of zinc and selenium supplementation…on thyroid inflammation factors and to indicate whether thyroid dysfunction can be prevented with Zn and Se supplementation or not.”
Source: Mahmoodianfard, Salma, et al. “Effects of zinc and selenium supplementation on thyroid function in overweight and obese hypothyroid female patients: a randomized double-blind controlled trial.” Journal of the American College of Nutrition 34.5 (2015): 391-399.
Posted May 4, 2015.
Greg Arnold is a Chiropractic Physician practicing in Hauppauge, NY. You can contact Dr. Arnold directly by emailing him at PitchingDoc@msn.com or visiting his web site at www.PitchingDoc.com.
References:
- “Hypothyroidism” posted on the National Institutes of Health Website
- Golden SH, Robinson KA, Saldanha I, Anton B, Ladenson PW. Prevalence and incidence of endocrine and metabolic disorders in the United States: a comprehensive review. Journal of Clinical Endocrinology & Metabolism. 2009;94(6):1853–1878
- Mahmoodianfard S Effects of Zinc and Selenium Supplementation on Thyroid Function in Overweight and Obese Hypothyroid Female Patients: A Randomized Double-Blind Controlled Trial. J Am Coll Nutr. 2015 Mar 11:1-9. [Epub ahead of print]
- Craig CL, Marshall AL, Sj€ostr€om M, Bauman AE, Booth ML, Ainsworth BE, Pratt M, Ekelund U, Yngve A, Sallis JF, Oja P: International physical activity questionnaire: 12-country reliability and validity. Med Sci Sports Exerc 35: 1381–1395, 2003
- Freake HC, Govoni KE, Guda K, Huang C, Zinn SA: Actions and interactions of thyroid hormone and zinc status in growing rats. J Nutr 131: 1135–1141, 2001
