Low-sulfur diet

A low-sulfur diet is a diet with reduced sulfur content. Sulfur containing compounds may also be referred to as thiols or mercaptans. Important dietary sources of sulfur and sulfur containing compounds may be classified as essential mineral (e.g. elemental sulfur), essential amino acid (methionine) and semi-essential amino acid (e.g. cysteine). Sulfur, as an essential mineral and as sulfur containing amino acids are fundamentally important to human health, and conditions such as nitrogen imbalance and protein-energy malnutrition may result from deficiency. Methionine cannot be synthesized by humans, and cysteine synthesis requires a steady supply of sulfur. The recommended daily allowance (RDA) of methionine (combined with cysteine) for adults is set at 13–14 mg kg-1 day-1 (13–14 mg per kg of body weight per day), but some researchers have argued that this figure is too low, and should more appropriately be 25 mg kg-1 day-1. Despite the importance of sulfur, restrictions of dietary sulfur are sometimes recommended for certain diseases and for other reasons. Practitioners of complimentary and alternative medicine also sometimes recommend low sulfur diets for the so-called dental amalgam mercury poisoning, a condition which is not accepted to exist by most mainstream experts.

Cystathionine beta-synthase deficiency
Cystathionine β-synthase (CBS) deficiency is a serious disorder of transsulfuration which is managed with methionine restricted dieting.

Lifespan alteration
Methionine restricted diets are also investigated for their possible role in prolonging lifespan (see methionine restriction).

Ulcerative colitis
Reduced dietary sulfur is investigated in ulcerative colitis research, but this is controversial.

Agriculture
In the farming industry, environmental concerns over air pollution lead to research aimed at reducing the odor of manure. A body of evidence emerged that increased sulfur containing amino acid content of feed increased the offensive odor of feces and flatus produced by livestock. This is thought to be due to increased sulfur containing substrate available to gut microbiota enabling increased volatile sulfur compound (VSC) release during gut fermentation (VSC are thought to be the primary contributors to the odor of flatus and feces). This theory is supported by the observation that feces from carnivores is more malodorous than feces from herbivore species, and this appears to apply to human diets as well (odor of human feces shown to increase with increased dietary protein, particularly sulfur containing amino acids).

"Amalgam toxicity"
Low sulfur diets are purported to be therapeutic for non medically recognized conditions such as "dental amalgam mercury poisoning".

Sulfur content of food
Generally, a low sulfur diet involves reduction of cruciferous vegetables (cauliflower, cabbage, cress, broccoli and other leafy vegetables), dairy products, eggs, onions and peas.