Iodine Testosterone Levels Men

Low iodine levels linked to higher testosterone in US men. Study suggests excess iodine may be harmful. #Iodine #Testosterone #Health

A study published in JAMA Network Open found that lower iodine concentrations in the urine were linked to higher testosterone levels in nearly 3,000 U.S. men. The researchers, led by Arcangelo Barbonetti, PhD, from the University of L'Aquila in Italy, discovered that men with lower urinary iodine concentrations had significantly higher total testosterone levels than men with normal or high iodine levels. This association remained even after adjusting for various factors such as BMI, blood pressure, glucose, triglycerides, HDL cholesterol, and creatinine, as well as demographic factors.

The study defined low iodine concentrations as being under 100 μg/L, normal between 100-299 μg/L, and high as 300 μg/L or over. Men in the lowest iodine category had median total testosterone levels of 446.70 ng/dL, while those in the normal and high categories had testosterone levels of 398.68 ng/dL and 398.50 ng/dL, respectively. The same trend was observed for calculated free testosterone levels.

The researchers suggested that excess iodine could directly affect testicular steroidogenesis, as seen in preclinical animal models where iodine accumulated in the testis and led to lower testosterone levels. They also noted that men in the low iodine category had the lowest levels of thyroid dysfunction compared to the normal and high categories, although the differences were not statistically significant.

Barbonetti expressed surprise at the findings, as iodine has traditionally been considered a harmless and beneficial element. He warned that iodine, when in excess, may be harmful to health and could be associated with extra-thyroid disorders, including androgen deficiency. He suggested that regulatory agencies should reconsider the mode and extent of iodine prophylaxis, especially in areas with iodine sufficiency.

The study included a total of 2,934 men with an average age of 47.1, and data was obtained from five cycles of the National Health and Nutrition Examination Survey. Men with lower urinary iodine concentrations tended to be younger and have better metabolic and glycolipid profiles, such as a lower BMI. This study highlights the potential impact of iodine on testosterone levels and the need for further research in this area.