The impact of nutrition on thyroid hormone physiology and action.

In summary, nutritionally directed alterations in thyroid hormone metabolism appear to be adaptive and to serve important protective roles in the overall economy of the body. These adjustments to nutrition are found at practically every level of thyroid regulation, beginning in the CNS and ending with the final action of thyroid hormones in the nucleus of cells. The cellular actions of thyroid hormones modify, and are modified by, as yet poorly understood interrelationships with substrates and other hormones. The level and composition of the energy intake, including whether the organism is in energy balance, are important signals directing these hormonal adaptations.