Antioxidant Plays a Role in Optimal Arterial Function

By CP Staff

A recently published clinical trial evaluated the impact of supplementation of a potent antioxidant on arterial function in subjects with subclinical hypothyroidism. Previous research has shown that individuals with subclinical hypothyroidism have impaired flow-mediated endothelial-dependent arterial dilation, which is a local mechanism in which the cells that line the arteries (endothelium) release substances to dilate the artery. Impairment of this mechanism is related to early atherosclerosis and increased blood pressure.

According to the American Association of Clinical Endocrinologists, subclinical hypothyroidism is a condition in which thyroid stimulating hormone is slightly elevated and may represent an early stage of decreased thyroid function. Approximately 1-10 percent of adults have this condition, and it progresses to overt hypothyroidism in 3-20 percent of individuals. Although it is often asymptomatic, it is associated with elevated blood lipids and cardiovascular and neuropsychiatric effects.

This new study assessed the potential effect of supplementation with the antioxidant alpha-lipoic acid on endothelial-dependent arterial dilation in subjects with subclinical hypothyroidism. The subjects included 40 women with recently diagnosed subclinical hypothyroidism and 18 healthy women with normal thyroid function. The women received alpha-lipoic acid or no treatment for 3 weeks. Flow-mediated endothelium-dependent arterial dilation was measured at the beginning of the study and again after the 3-week intervention. Additionally, levels of plasma thiobarbituric acid reactive substances, a measurement of lipid peroxidation and oxidative stress, were evaluated.

The study showed that levels of plasma thiobarbituric acid reactive substances decreased significantly in the subjects supplemented with alpha-lipoic acid compared to the levels in the subjects at the beginning of the study. There was no change in plasma thiobarbituric acid reactive substances in the subjects who received no treatment. Additionally, flow-mediated endothelium-dependent arterial dilation improved in the subjects receiving alpha-lipoic acid, while there was no change seen in the subjects in the non-intervention group. The improvement in flow-mediated endothelium-dependent arterial dilation correlated to the decrease in plasma thiobarbituric acid reactive substances.

The study authors concluded that their data showed that subclinical hypothyroidism patients have impaired endothelial function, and that the “antioxidant alpha-lipoic acid can improve endothelial function, through decrease of oxygen-derived free radicals.”

Reference:

Gd X, Jh P, Hl S, Ls Z. Alpha-lipoic Acid Improves Endothelial Dysfunction in Patients with Subclinical Hypothyroidism. Exp Clin Endocrinol Diabetes. 2010 Feb 16. Published Online Ahead of Print. PMID: 20162509.