Written by Greg Arnold, DC, CSCS. In this study of 84 healthy premenopausal women (aged 17 – 50), those who took 25000 IU of Vitamin A daily for 4 months decreased their thyroid stimulating hormones to normal levels compared to placebo. Researchers suggested that Vitamin A is effective in correcting mild thyroid abnormalities.

A thyroid condition called “subclinical hypothyroidism” is characterized by a mild elevation of a hormone called thyroid-stimulating hormone and normal levels of a hormone called T4. But subclinical hypothyroidism can progress to full-blown hypothyroidism, which can cause high blood pressure, high cholesterol levels, and other cardiovascular problems (1).

Although the prescription medication levothyroxine has shown “several clinical benefits” (1), it can also have significant side effects (2). As a result, finding natural ways to help maintain thyroid health would be a benefit. Now a 2014 study (3) suggests vitamin A supplementation may help normalize thyroid function.

In the study, 84 healthy premenopausal women aged 17 to 50 were given either vitamin A (25,000 International Units per day as retinyl palmitate given in 1 capsule) or placebo for 4 months. Blood samples were drawn before and after the study to measure for thyroid function. The researchers decided to study women of reproductive age, as they are one of the most vulnerable groups for vitamin A deficiency and thyroid dysfunction (4).

Of the 84 women in the study, 56 were obese (body mass index between 30 and 35 kg/m2) and 28 were not obese (body mass index between 18.5 and 24.9 kg/m2). The 56 obese women received either vitamin A or placebo and all non-obese women received vitamin A (no placebo group for non-obese women).

After 4 months, the researchers noted the following changes between the three groups:

What was MeasuredObese Vitamin AObese PlaceboNonobese vitamin Ap value
Thyroid-Stimulating Hormone(milli-International Units)29.9% decrease(3.08 to 2.16)11.6% decrease(3.71 to 3.28)33.3% decrease(3.0 to 2.0)0.004
T3 Hormone, Total(nanomoles/Liter)38.2% increase(2.04 to 2.82)17.3% increase(2.31 to 2.71)61.1% increase(1.88 to 3.03)< 0.001
T4 Hormone, Total(nmol/L)16.5% decrease(124.37 to 103.88)23.5% decrease(118.86 to 90.95)22.6% decrease(123.40 to 95.63)< 0.001

The most significant finding in these results is the normalizing of thyroid-stimulating hormone levels in the vitamin A group, eventually falling into the 0.3-3.0 milli-International Units range as recommended by the American Association of Clinical Endocrinologists (4). The placebo group did not achieve normal thyroid-stimulating hormone levels.

Regarding Total T3 hormone levels, the current recommendations are 1.1-3.0 nmol/L (5).

Regarding Total T4 hormone levels, the current recommendations are 64-155 nmol/L (5)

For the researchers, “it is likely that [Vitamin A given as retinyl palmitate] supplementation at 25,000 IU/d is effective for correcting mild thyroid abnormalities and reducing the risk of subclinical hypothyroidism in premenopausal women” but that “additional studies are needed to evaluate the iodine status and to clarify the possible different sex-related effects of vitamin A on thyroid function.”

Source: Farhangi, Mahdieh Abbasalizad, et al. “The effect of vitamin A supplementation on thyroid function in premenopausal women.” Journal of the American College of Nutrition 31.4 (2012): 268-274.

© The Author(s). 2016 Creative Commons Attribution 4.0 International License (http://creativecommons.org/licenses/by/4.0/)

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Posted May 11, 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:

  1. Papi G, Uberti ED, Betterle C, Carani C, Pearced EN, Bravermand LE, Roti E: Subclinical hypothyroidism. Curr Opin Endocrinol Diabetes Obes 14:197–208, 2007
  2. Biondi B, Fazio S, Carella C, Amato G, Cittadini A, Lupoli G, Sacca L, Bellastella A, Lombardi G: Cardiac effects of long term thyrotropin-suppressive therapy with levothyroxine. J Clin Endocrinol Metab 77:334–338, 1993
  3. Farhangi MA.  The effect of vitamin A supplementation on thyroid function in premenopausal women.  J Am Coll Nutr 2012 Aug;31(4):268-74
  4. Baskin HJ, Cobin RH, Duick DS, Gharib H, Guttier RB, Kaplan MM, Segal RL: American Association of Clinical Endocrinologists. American Association of Clinical Endocrinologists medical guidelines for clinical practice for the evaluation and treatment of hyperthyroidism and hypothyroidism. Endocr Pract 8:457–469, 2002
  5. American College of physicians, Normal Lab Values Reference Table. Accessed April 16, 2015 (https://www.acponline.org/clinical_information/resources/normal_lab_values.htm https://www.acponline.org/clinical_information/resources/normal_lab_values.htm