3 min readApr 29, 2026 06:16 AM IST First published on: Apr 29, 2026 at 06:16 AM ISTAt a time when non-communicable diseases dominate global health conversations, the thyroid gland, small yet metabolically powerful, is emerging as a barometer of how modern life is altering human biology. At the 35th annual scientific meeting of the American Association of Clinical Endocrinology in Las Vegas, the Hossein Gharib Educational Lectureship offered an opportunity to reflect on a small gland with a large message. The lecture, ‘Impact of Iodine on Thyroid Autoimmunity, Goiter and Oncogenesis’, centred on one simple truth: In thyroid physiology, more is not always better. Both deficiencies and excess can be harmful. The thyroid operates within a narrow biological window, and when iodine intake strays outside this range, disease follows.The thyroid gland lives by balance. Too little iodine, and it struggles — goiter, hypothyroidism, nodular disease, impaired neurodevelopment. Too much, and it may rebel — autoimmunity, thyrotoxicosis, thyroiditis, altered disease patterns. Endocrinologists call this a U-shaped curve. Life calls it wisdom. For decades, iodine deficiency was the enemy. Iodised salt became one of public health’s greatest success stories, including in India. But today, iodine exposure is no longer limited to dieting. Iodine also comes from supplements, seaweed-based products, processed foods, iodinated contrast, antiseptics, and unregulated “health” practices. Environmental exposures, from plastics like bisphenol A to fluoride and other endocrine-disrupting chemicals, are interacting with iodine biology in ways that amplify risk.AdvertisementThe thyroid is exquisitely sensitive to such shifts. It needs iodine to make T3 and T4, hormones that influence metabolism, growth, energy, and brain development. Yet when iodine crosses its biological threshold, the same nutrient can disturb the very gland it was meant to nourish. Truly, dose becomes biology. Even more concerning is the growing evidence that excess iodine may enhance thyroid autoimmunity. A newer concern is the “double hit” model, where iodine imbalance interacts with endocrine-disrupting chemicals, which may interfere with thyroid hormone signalling, iodine uptake, and immune balance. There is also growing evidence linking iodine excess to cardiovascular changes, metabolic dysfunction, and alterations in the gut microbiome, the complex ecosystem increasingly recognised as central to immune and endocrine health. This is where medicine must become more attentive. Behind every TSH, T3, and T4 value is a person — what they eat, what they inhale, what they apply, what they believe is “natural,” and what their body is trying to balance.The lesson is also spiritual. Vedanta has long taught that harmony, not accumulation, sustains life. The Bhagavad Gita reminds us that moderation in food, sleep, action, and thought leads to well-being. The thyroid seems to repeat the same truth: Neither deprivation nor excess creates health. Endocrinology calls this homeostasis. Indian wisdom calls it samatva — equanimity, balance. In iodine intake, as in human living, the path is not “more” or “less,” but “right”. The future of medicine must therefore move from precision treatment to precision balance — knowing what is enough, what is too much, and what each individual truly needs. Health is not the victory of excess. It is the art of alignment.The writer is a consultant endocrinologist at Lilavati Hospital and Research Centre based in Mumbai, a Padma Shri awardee and a recipient of the Hossein Gharib Educational Lectureship at AACE 2026