Sulfur is an interesting nonmetallic element that is found mainly as part of larger compounds. It is not discussed much in nutrition books, mainly because it has not been thought to be essential—that is, sulfur deficiency does not cause any visible problems.
Sulfur represents about 0.25 percent of our total body weight, similar to potassium. The body contains approximately 140 grams of sulfur-mainly in the proteins, although it is distributed in small amounts in all cells and tissues. Sulfur has a characteristic odor that can be smelled when hair or sheep's wool is burned. Keratin, present in the skin, hair, and nails, is particularly high in the amino acid cystine, which is found in sulfur. The sulfur-sulfur bond in keratin gives it greater strength.
Sulfur is present in four amino acids: methionine, an essential amino acid; the nonessential cystine and cysteine, which can be made from methionine; and taurine, which is not part of body tissues but does help produce bile acid for digestion. Sulfur is also present in two B vitamins, thiamine and biotin; interestingly, thiamine is important to skin and biotin to hair. Sulfur is also available as various sulfates or sulfides. But overall, sulfur is most important as part of protein.
Sulfur has been used commonly since the early 1800s. Grandma's "spring tonic" consisted mainly of sulfur and molasses. This also acted as a laxative. Sulfur has been known as the "beauty mineral" because it helps the complexion and skin stay clear and youthful. The hydrogen sulfide gas in onions is what causes tearing. This gas can also be made by intestinal bacteria and is absorbed by the body or released as gas with a characteristic odor.
Sulfur is absorbed from the small intestine primarily as the four sulfur-containing amino acids or from sulfates in water or fruits and vegetables. It is thought that elemental sulfur is not used by the human organism. Sulfur is stored in all body cells, especially the skin, hair, and nails. Excess amounts are eliminated through the urine or in the feces.
Sources: As part of four amino acids, sulfur is readily available in protein foods-meats, fish, poultry, eggs, milk, and legumes are all good sources. Egg yolks are one of the better sources of sulfur. Other foods that contain this somewhat smelly mineral are onions, garlic, cabbage, brussels sprouts, and turnips. Nuts have some, as do kale, lettuce, kelp and other seaweed, and raspberries. Complete vegetarians (those who eat no eggs or milk) and people on low-protein diets may not get sufficient amounts of sulfur; the resulting sulfur deficiency is difficult to differentiate clinically from protein deficiency, which is of much greater concern.
Functions: As part of four amino acids, sulfur performs a number of functions in enzyme reactions and protein synthesis. It is necessary for formation of collagen, the protein found in connective tissue in our bodies. Sulfur is also present in keratin, which is necessary for the maintenance of the skin, hair, and nails, helping to give strength, shape, and hardness to these protein tissues. Sulfur is also present in the fur and feathers of other animals. The cystine in hair gives off the sulfur smell when it is burned. Sulfur, as cystine and methionine, is part of other important body chemicals: insulin, which helps regulate carbohydrate metabolism, and heparin, an anticoagulant. Taurine is found in bile acids, used in digestion. The sulfur-containing amino acids help form other substances as well, such as biotin, coenzyme A, lipoic acid, and glutathione. The mucopoly-saccharides may contain chondroitin sulfate, which is important to joint tissues.
Sulfur is important to cellular respiration, as it is needed in the oxidation-reduction reactions that help the cells utilize oxygen, which aids brain function and all cell activity. These reactions are dependent on cysteine, which also helps the liver produce bile secretions and eliminate other toxins. L-cysteine is thought to generally help body detoxification mechanisms through the tripeptide compound, glutathione.
Uses: In its elemental form, sulfur was used for many disorders during the nineteenth century. In the twentieth century, the focus is more on the sulfur-containing amino acids, used internally; or as elemental sulfur-containing ointments used for skin disorders such as eczema, dermatitis, and psoriasis. Psoriasis has been treated with oral sulfur along with zinc. Other problems of the skin or hair have been treated with additional sulfur-containing compounds.
Joint problems may be helped by chondroitin sulfate, which is found in high amounts in the joint tissues. For centuries, arthritis sufferers have been helped by bathing in waters that contain high amounts of sulfur. Oral sulfur as sulfates in doses of 500-1,000 mg. may also reduce symptoms in some patients. Magnesium sulfate, which is not absorbed, has been used as a laxative. Taurine, another sulfur-containing amino acid, has been used in epilepsy treatment, usually along with zinc. A physiologic form of sulfur called methylsulfonyl methane (MSM) has recently become available and may be helpful in patients with allergies (see Chapter 7, Accessory Nutrients).
If we need additional sulfur, we can get it by eating an egg or two a day or eating extra garlic or onions, as well as other sulfur foods. There is no real cause for concern about the cholesterol in eggs if the diet is generally low in fat and blood cholesterol level is not elevated.
Deficiency and toxicity: There is minimal reason for concern about either toxicity or deficiency of sulfur in the body. No clearly defined symptoms exist with either state. Sulfur deficiency is more common when foods are grown in sulfur-depleted soil, with low-protein diets, or with a lack of intestinal bacteria, though none of these seems to cause any problems in regard to sulfur functions and metabolism.
Requirements: There is no specific RDA for sulfur other than the amino acids of which they are part are needed to meet protein requirements. Our needs are usually easily met through diet. About 850 mg. are thought to be needed for basic turnover of sulfur in the body. There is not much information available on sulfur content of foods, nor are there supplements specifically for sulfur. I have found that it is not really a nutritional concern.