Physiological functions of Sulfur Sulfur helps proteins stay rigid. There is no known RDA or minimum requirement for sulfur. The trace minerals are named so because the body needs such small amounts that it is not possible to construct a deficient human diet. The trace minerals that have RDA's established include iodine, iron, zinc and selenium. Safe and Adequate Daily Dietary Intakes have been established for copper, manganese, fluoride, chromium and molybdenum.
Human requirements are under study for arsenic, nickel, silicon and boron.
Iodine is needed by the body in extremely small quantities. It is a part of the hormone thyroxin. If iodine is low in the body, the thyroid gland enlarges to try to make more thyroxin. This causes a lump on the neck known as goiter. Oversupply of iodine can also cause a lump in the neck.