Biotin
Biotin (less commonly known as vitamin B7) is a water-soluble vitamin, part of the vitamin B complex, and a coenzyme for many reactions, including gluconeogenesis and the synthesis of fatty acids and amino acids.
Biotin deficiency is very rare.
Biotin excess does not seem to produce any ill-effects . However large doses of biotin in those on vitamin supplements may interfere with biochemical assays leading to misdiagnoses e.g. hyperthyroidism .
Recent work suggests that biotin may have a role in the treatment of secondary progressive multiple sclerosis .
Interestingly, it was formerly known as vitamin H or coenzyme R.