Athletes and Iodine Deficiency

According to recent research, iodine deficiency has increased fourfold over the past 40 years, and 74 percent of adults might not get adequate amounts. This is especially concerning to those who eat balanced and exercise regularly because iodine is pretty much devoid from most vegetables, meats and fruit, and you lose large amounts when you sweat, especially in hot, humid environments. To throw another wrench into the works, certain minerals block iodine from functioning properly: fluoride from our water system and bromide from pesticides, soft drinks and many commercial baked goods. But what about athletes?

Normal exercise increases the amount of iodine in the thyroid gland. As exercise increases metabolic activity and thyroid hormones drive metabolic rate (among many factors). This makes physiologic sense as exercise increases thermogenesis and metabolism – both tightly connected with the increased production of thyroid hormones. A Russian study of 3000-meter runners, had a higher iodine uptake in the thyroid gland compared to sedentary controls. Another interesting study showed that a soccer team in training had thyroid enlargement from iodine deficiency as compared with sedentary controls. Replacement of electrolytes and minerals is an established practice. However, given the rigorous training protocols of many athletes it is easy to have an iodine deficiency. The far right table shows that iodine excretion can reach nearly 2 milligrams after 7 days. It may not seem like a lot, but this can cause thyroid problems!

By far, the most important pathway of iodine loss (approximately 90%) is through urinary excretion (see above). But other losses come from exhalation from the lungs and sweating from the skin. Iodine loss in sweat can be very important for athletes. One Japanese study showed that the iodine content in sweat was about 0.4 mg per liter of sweat. This may not sound like a lot, but in a heavy sweater with an iodine poor diet, at high altitude, this could be significant. Be conscious of your iodine intake and you could notice a burst of energy, improved results in the gym and a more positive outlook in general.