The effect of vitamin A supplementation on thyroid function in premenopausal women

J Am Coll Nutr. 2012 Aug;31(4):268-74. doi: 10.1080/07315724.2012.10720431.


Objective: Vitamin A and its retinoid derivates play an important role in regulation of normal growth and development. Vitamin A has been shown to regulate thyroid hormone metabolism and inhibit thyroid-stimulating hormone (TSH) secretion via down regulation of TSH-β gene expression; however, the effect of vitamin A on thyroid function in obese individuals who are at higher risk of subclinical hypothyroidism is still unclear. In the present study we investigate the impact of vitamin A supplementation on thyroid function in obese women.

Method: A 4-month randomized, double blind controlled trial was conducted among 84 healthy women aged 17-50 years old: 56 were obese (body mass index [BMI] 30-35 kg/m(2)) and 28 were nonobese (BMI 18.5-24.9 kg/m(2)). Obese women were randomly allocated to receive either vitamin A (25,000 IU/d retinyl palmitate) or placebo. Nonobese women received vitamin A. At baseline and 4 months after intervention, serum concentrations of TSH, total thyroxine (T4), total triiodothyronine (T3), retinol-binding protein (RBP), and transthyretin (TTR) were measured.

Results: Baseline concentrations of thyroid hormones, RBP and TTR were not significantly different between groups. Vitamin A caused a significant reduction in serum TSH concentrations in obese (p = 0.004) and nonobese (p = 0.001) groups. Serum T3 concentrations also increased in both obese and nonobese vitamin A-treated groups (p < 0.001). Serum T4 decreased in all 3 groups after treatment. The results showed a significant reduction in serum RBP in the obese group after vitamin A supplementation (p = 0.007), but no significant change was seen in serum TTR.

Conclusions: Serum TSH concentrations in vitamin A-treated subjects were significantly reduced; therefore, vitamin A supplementation might reduce the risk of subclinical hypothyroidism in premenopausal women.

Publication types

  • Randomized Controlled Trial
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adolescent
  • Adult
  • Body Mass Index
  • Dietary Supplements*
  • Double-Blind Method
  • Down-Regulation
  • Female
  • Humans
  • Hypothyroidism / physiopathology
  • Hypothyroidism / prevention & control
  • Middle Aged
  • Obesity / drug therapy
  • Prealbumin / analysis
  • Premenopause / drug effects
  • Retinol-Binding Proteins / analysis
  • Thyroid Gland / drug effects*
  • Thyroid Gland / metabolism
  • Thyrotropin / blood
  • Thyrotropin, beta Subunit / analysis
  • Thyroxine / blood
  • Triiodothyronine / blood
  • Vitamin A / administration & dosage*
  • Young Adult


  • Prealbumin
  • Retinol-Binding Proteins
  • Thyrotropin, beta Subunit
  • Triiodothyronine
  • Vitamin A
  • Thyrotropin
  • Thyroxine