<unk>  is an essential trace element in<unk> cal systems. It has the distinction of being the heaviest element commonly needed by living organisms as well as the second-heaviest known to be used by any form of life (only tungsten, a component of a few bacterial enzymes, has a higher atomic number and atomic weight). It is a component of biochemical pathways in organisms from all<unk> cal kingdoms, suggesting its fundamental significance throughout the evolutionary history of life.<unk>  is critical to the proper functioning of the vertebrate endocrine system, and plays smaller roles in numerous other organs, including those of the digestive and reproductive systems. An adequate intake of<unk> -containing compounds is important at all stages of development, especially during the fetal and neonatal periods, and diets deficient in<unk>  can present serious consequences for growth and metabolism.
Iodine in biology
Selenium in biology
Thyroid's secretory capacity
Biological aspects of fluorine
Estrogenic fat
Thyroid hormones
Estrogenic substances
Hormone