Sulfur exists in the body as a constituent of three amino acids – cysteine, cystine, and methionine and of many other organic molecules. It exists as part of these organic molecules in all cells and extracellular compartments such as connective tissues.
Sulfur acts primarily as a component of organic molecules in cells rather than as an inorganic element. The sulfur atoms remain part of the organic structures until hepatic degradation of the cysteine and the formation of inorganic sulfate groups that are excreted by the kidneys. Several nonhepatic cells use sulfate for the synthesis if iron-sulfur proteins. In addition, structural molecules within cells contain sulfated monosaccharide residues. Taurine, a sulfur-containing amino acid made by liver cells, is used to conjugate bile acids before secretion.
Excess inorganic sulfur generated as a result of hepatic or renal metabolism is excreted in the urine as sulfates. The metabolism of sulfur-containing amino acids generates inorganic acids, especially sulfate anions, in substantial amounts. These sulfates are thought to combine with calcium ions in the glomerular ultrafiltrate, thereby reducing the renal tubular resorption of calcium. That is why as much as 50% of the calcium loss associated with protein-induced hypercalciuria, which develops after consumption of meals rich in animal proteins – proteins that are rich in sulfur.
Sulfur are primarily found in unprocessed animal foods and seafood. It is also found in great abundance in raw egg yolks.
Sulfur deficiency is a big threat to vegans and vegetarians that do not consume any eggs or dairy food.
Dietary reference intake
There are no DRIs for sulfur.
Sulfur content of selected foods
Sulfur deficiency is rare because it is available in many food sources, and it is also synthesized in the body from the breakdown of proteins. Sulfur deficiency causes difficulty in synthesizing proteins, as well as poor muscle mass and weakness. Because sulfur deficiency usually only occurs when there is also a protein deficiency, it is difficult to know which symptoms are caused by a deficiency in sulfur and which are caused by a deficiency in protein.
Sulfur toxicity is highly unlikely.