Melatonin, a sleep-inducing hormone, can reduce oxidative stress, a condition in which byproducts from the interaction of oxygen with molecules cause cell damage. Hypothyroidism, a condition in which the thyroid gland is underactive, may be associated with oxidative stress. Though melatonin helps prevent oxidative stress, evidence suggests that melatonin may reduce the growth and activity of the thyroid gland. So it may not be safe for individuals with hypothyroidism to take melatonin. Always consult with your physician before taking any new supplement.
Hypothyroidism
Hypothyroidism is a condition in which the activity in the thyroid gland is lower than normal. As a result, the thyroid gland secretes reduced amounts of thyroid hormone. Thyroid hormones are responsible for maintaining a normal metabolic rate. When the activity in the gland decreases, the metabolic rate drops. This normally leads to weight gain. Hypothyroidism can be an autoimmune disease, a condition in which your own immune system attacks the gland. It can also result from an iodine deficiency or from a common treatment of hyperthyroidism that destroys the thyroid gland.
Hypothyroidism and Oxidative Stress
Scientists disagree about whether hypothyroidism causes oxidative stress. A study of younger women with hypothyroidism published in the August 2009 issue of "Acta Bio Medica" didn't find an increase in oxidative stress. The authors suggest that the conflicting results in this area of research may be due to the difficulty of studying the link between oxidative stress and thyroid dysfunction. Both oxidative stress and the activity of the thyroid gland depend on environmental factors, such as diet and exposure to pollution, which can be difficult to control for.
Hypothyroidism and Cholesterol
A study of hyperthyroid women published in the November 2010 issue of "Clinical Chemistry and Laboratory Medicine" looked at both dietary factors and thyroid hormones in relation to oxidative stress. The researchers found increased oxidative stress and increased levels of low-density lipoprotein, or bad cholesterol, decreased levels of high-density lipoprotein and increased levels of triglycerides in the groups with hypothyroidism. They also found that the bad cholesterol levels had a greater impact on oxidative stress than the dysfunction of the thyroid gland. So oxidative stress may be an indirect effect of hypothyroidism.
Melatonin
Melatonin plays a crucial role in regulating the human 24-hour cycle, also known as the circadian rhythm. In synthetic form, melatonin may help regulate sleep. Melatonin is also an antioxidant that can help reduce oxidative stress. A study published in the February 2001 issue of "Experimental Gerontology" further showed that melatonin may help regulate the activity level of the thyroid gland in individuals with hypothyroidism linked to the onset of menopause. However, according to a review of the existing scientific evidence published in the April 2002 issue of "Neuro Endocrinology Letters," melatonin can inhibit thyroid function, which can worsen hypothyroidism. So taking melatonin with hypothyroidism may be unsafe.
References
- Mayo Clinic: Hypothyroidism
- "Acta Biomedica"; Serum Oxidative Stress Parameters of Women with Hypothyroidism; M.J. Coria, et al.; August 2009
- "Clinical Chemistry and Laboratory Medicine"; Association Between Thyroid Hormones, Lipids and Oxidative Stress Biomarkers in Overt Hypothyroidism; A. Santi, et al.; November 2010
- "Experimental Gerontology"; Effects of Melatonin in Perimenopausal and Menopausal Women: A Randomized and Placebo Controlled Study; G. Bellipanni, et al.; February 2001
- "Neuro Endocrinology Letters"; Melatonin and the Thyroid Gland; A. Lewinski, et al.; April 2002
