Subclinical hypothyroidism less likely for men with higher dietary vitamin E intake
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Key takeaways:
- Men with a daily dietary vitamin E intake of 4.5 mg or higher had lower odds for subclinical hypothyroidism.
- Vitamin E intake was not linked to lower odds for any thyroid dysfunction for women.
Men who consumed more dietary vitamin E may be less likely to develop subclinical hypothyroidism and autoimmune thyroiditis, though no associations were observed among women, according to findings published in Thyroid.
“At present, research on the relationship between vitamin E and thyroid dysfunction consists primarily of small-sample case-control studies or animal experiments,” Yongze Li, MD, PhD, and Tingting Liu, MD, PhD, of the department of endocrinology and metabolism, Institute of Endocrinology, NHC Key Laboratory of Diagnosis and Treatment of Thyroid Diseases at the First Hospital of China Medical University in Shenyang, China, and colleagues wrote. “Our study, conducted from a population perspective, explored the association between dietary vitamin E intake and thyroid dysfunction, providing evidence for a potential association of lower prevalence rates of subclinical hypothyroidism and autoimmune thyroiditis with increased dietary vitamin E intake.”
Researchers conducted a cross-sectional study using data from the National Health and Nutrition Examination Survey. The study included 7,773 adults with complete dietary intake and thyroid measures who did not have preexisting thyroid disease from 2007 to 2012. Free triiodothyronine, total T3, total thyroxine, free T4, thyroid-stimulating hormone, thyroid peroxidase antibodies and thyroglobulin antibodies were measured. Thyroid measures were used to define subclinical hypothyroidism, overt hypothyroidism and autoimmune thyroiditis. Vitamin E intake was assessed in a 24-hour dietary recall. Participants were divided into tertiles based on vitamin E intake. The lowest tertile group had a daily vitamin E intake of 4.53 mg or less, the moderate group had vitamin E intake of 4.54 mg to 8.1 mg and the highest group had a vitamin E intake of 8.11 mg or higher.
The study group had a mean vitamin E intake of 8.6 mg per day. The proportion of adults who met the recommended daily vitamin E intake of 15 mg was 11.8%.
In fully adjusted logistic regression analysis, adults in the highest tertile for vitamin E intake were less likely to have subclinical hypothyroidism than adults in the lowest tertile (adjusted OR = 0.28; 95% CI, 0.15-0.54; P < .001). Vitamin E intake did not affect risk for overt hypothyroidism or autoimmune thyroiditis.
In subgroup analysis, men in the moderate (aOR = 0.45; 95% CI, 0.23-0.87; P = .02) and highest tertiles (aOR = 0.19; 95% CI, 0.09-0.39; P < .001) for vitamin E intake were less likely to have subclinical hypothyroidism than men in the lowest tertile. Men in the moderate (aOR = 0.59; 95% CI, 0.37-0.93; P = .024) and highest tertiles (aOR = 0.52; 95% CI, 0.36-0.75; P < .001) for vitamin E intake were also less likely to have autoimmune thyroiditis than men in the lowest tertile. No associations were observed for women.
“We found that moderate to high dietary vitamin E intake was associated with a reduced prevalence of autoimmune thyroiditis in males,” the researchers wrote. “Similar reports have also indicated a protective effect of vitamin E in other autoimmune diseases, such as asthma and inflammatory bowel disease. This association may be attributed to the direct immunomodulatory functions of vitamin E.”
The researchers cautioned that causality could not be established in the study due to its cross-sectional nature. They also said randomized controlled trials are needed to assess the effects of vitamin E supplementation among adults with subclinical hypothyroidism or autoimmune thyroiditis.
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