Low-sulfur diet

A low-sulfur diet is a diet with reduced sulfur content. 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 is an essential dietary mineral primarily because amino acids contain it. Sulfur is thus considered 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.^{[citation needed]}

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.^[1]

Despite the importance of sulfur, restrictions of dietary sulfur are sometimes recommended for certain diseases and for other reasons.^{[citation needed]}

Cystathionine beta-synthase deficiency

Cystathionine β-synthase (CBS) deficiency is a serious disorder of transsulfuration which is managed with methionine restricted dieting.^[2]

Food sources of Methionine^[3]
Food	g/100g
Egg, white, dried, powder, glucose reduced	3.204
Sesame seeds flour (low fat)	1.656
Egg, whole, dried	1.477
Cheese, Parmesan, shredded	1.114
Brazil nuts	1.008
Soy protein concentrate	0.814
Chicken, broilers or fryers, roasted	0.801
Fish, tuna, light, canned in water, drained solids	0.755
Beef, cured, dried	0.749
Bacon	0.593
Beef, ground, 95% lean meat / 5% fat, raw	0.565
Pork, ground, 96% lean / 4% fat, raw	0.564
Wheat germ	0.456
Oat	0.312
Peanuts	0.309
Chickpea	0.253
Corn, yellow	0.197
Almonds	0.151
Beans, pinto, cooked	0.117
Lentils, cooked	0.077
Rice, brown, medium-grain, cooked	0.052

Agriculture

In the farming industry, environmental concerns over air pollution led 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.^[4]

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,^{[citation needed]} 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).^[5]^[6]