Although turmeric has been used medicinally for at least 4,000 years, there are no clinical studies and few peer-reviewed, evidence-based studies regarding the effect of turmeric on your thyroid. The lack of studies is surprising because alternative practitioners claim that turmeric might help everything from fibromyalgia to ringworm and Alzheimer's disease. If you're concerned about the health of your thyroid, double-check with your doctor. Simple thyroid function tests can determine whether there is a real problem.
Thyroid Function
Your pituitary gland secretes thyroid stimulating hormone, or TSH. TSH causes your thyroid gland to produce two hormones called thyroxine and triiodothyronine, better known as T4 and T3. T4 and T3 work together to regulate cellular metabolism. Cellular metabolism refers to how effectively the cells use glucose. A thyroid function test measures the levels of TSH, T4 and T3 in your blood.
Turmeric
Turmeric plays a central role in Ayurvedic and Chinese medical traditions, as well as in Indian cuisine. The active ingredient is curcumin.The mechanism of action is unknown, but is probably related to its antioxidant and anti-inflammatory properties. In the kitchen, this spice provides a yellow color to curries, dals and rice.
Animal Studies
The June 2002 issue of the "Indian Journal of Experimental Biology" included a study in which the diet of lab rats with an induced thyroid disorder was supplemented with vitamin E, vitamin C or turmeric extract. The two sets of control animals were a group of healthy animals with no supplements and a group of animals with the induced thyroid disorder that did not receive any supplements. While levels of T3 and T4 in control rats with the thyroid condition were lower than other controls, levels of T3 and T3 in animals receiving any of these supplements were less suppressed. As of 2011, this single result has not been replicated. Conclusions based on a study in rats in which a thyroid condition was artificially induced may have little relevance to human thyroid problems.
Safety Concerns
While the Maryland Medical Center reports that the amount of turmeric found in food is safe, higher doses might adversely affect your thyroid. A November 1985 study appearing in "Food Chemistry and Toxicology" examined the effect of high doses of turmeric in pigs. Groups of pigs were fed either 60, 296 and 1,551 mg/kg body weight/day for more than three months. At the end of the study, hyperplasia, or uncontrolled cell growth, of the thyroid was observed in the two higher-dose groups. A similar hyperplasia was observed in rats and mice used in a two-year study published by the National Toxicology Program in the August 1993 "National Toxicology Program Technical Report Series."
References
- "Indian Journal of Experimental Biology"; Effect of Antioxidants (Vitamin C, E and Turmeric Extract) on Methimazole Induced Hypothyroidism in Rats; U.R. Deshpande, et al.; June 2002
- "Food Chemistry and Toxicology"; Subchronic Oral Toxicity of Turmeric Oleoresin in Pigs; N. Bille, et al.; November 1985
- "National Toxicology Program Technical Report Series"; NTP Toxicology and Carcinogenesis Studies of Turmeric Oleoresin (CAS No. 8024-37-1) (Major Component 79%-85% Curcumin, CAS No. 458-37-7) in F344/N Rats and B6C3F1 Mice (Feed Studies). National Toxicology Program; August 1993
- Medline Plus: Turmeric
- University of Maryland Medical Center: Turmeric
- American Thyroid Association: Thyroid Function Test
