<unk>  is a water-soluble B vitamin. Consumption of large amounts as a dietary supplement results in absorption, followed by excretion into urine as<unk> . Consumption of<unk>  as part of a normal diet results in urinary excretion of<unk>  and<unk>  metabolites. Absorption<unk>  in food is bound to proteins. Digestive enzymes reduce the proteins to<unk> -bound peptides. The intestinal enzyme<unk> idase, found in pancreatic secretions and in the brush border membranes of all three parts of the small intestine, frees<unk> , which is then absorbed from the small intestine. When consumed as a<unk>  dietary supplement, absorption is nonsaturable, meaning that even very high amounts are absorbed effectively. Transport across the jejunum is faster than across the ileum. The large intestine microbiota synthesize amounts of<unk>  estimated to be similar to the amount taken in the diet, and a significant portion of this<unk>  exists in the free (protein-unbound) form and, thus, is available for absorption. How much is absorbed in humans is unknown, although a review did report that human epithelial cells of the colon in vitro demonstrated an ability to uptake<unk> . Once absorbed, sodium-dependent multivitamin transporter (SMVT) mediates<unk>  uptake into the liver. SMVT also binds pantothenic acid, so high intakes of either of these vitamins can interfere with transport of the other. Metabolism and excretion<unk>  catabolism occurs via two pathways. In one, the valeric acid sidechain is cleaved, resulting in bisnorbiotin. In the other pathway, the sulfur is oxidized, resulting in<unk>  sulfoxide. Urine content is proportionally about half<unk> , plus bisnorbiotin,<unk>  sulfoxide, and small amounts of other metabolites. Factors that affect<unk>  requirements Chronic alcohol use is associated with a significant reduction in plasma<unk> . Intestinal<unk>  uptake also appears to be sensitive to the effect of the anti-epilepsy drugs carbamazepine and primidone. Relatively low levels of<unk>  have also been reported in the urine or plasma of patients who have had a partial gastrectomy or have other causes of achlorhydria, burn patients, elderly individuals, and athletes. Pregnancy and lactation may be associated with an increased demand for<unk> . In pregnancy, this may be due to a possible acceleration of<unk>  catabolism, whereas, in lactation, the higher demand has yet to be elucidated. Recent studies have shown marginal<unk>  deficiency can be present in human gestation, as evidenced by increased urinary excretion of 3-hydroxyisovaleric acid, decreased urinary excretion of<unk>  and bisnorbiotin, and decreased plasma concentration of<unk> .
Biotin
Selenous acid
Zinc
Iron
Copper 
Cerate
Sybil 
Calamine