Thiamine (B₁)

Thiamine pyrophosphate

Aldehyde transfer

Beriberi (weight loss, heart problems, neurological dysfunction)

Riboflavin (B₂)

Flavin adenine dinucleotide (FAD)

Oxidation–reduction

Cheliosis and angular stomatitis (lesions of the mouth), dermatitis

Pyridoxine (B₆)

Pyridoxal phosphate

Group transfer to or from amino acids

Depression, confusion, convulsions

Nicotinic acid (niacin) (B₃)

Nicotinamide adenine dinucleotide (NAD⁺)

Oxidation–reduction

Pellagra (dermatitis, depression, diarrhea)

Pantothenic acid (B₅)

Coenzyme A

Acyl-group transfer

Hypertension

Biotin (B₇)

Biotin–lysine adducts (biocytin)

ATP-dependent carboxylation and carboxyl-group transfer

Rash about the eyebrows, muscle pain, fatigue (rare)

Folic acid (B₉)

Tetrahydrofolate

Transfer of one-carbon components; thymine synthesis

Anemia, neural-tube defects in development

B₁₂

5′-Deoxyadenosyl cobalamin

Transfer of methyl groups; intramolecular rearrangements

Anemia, pernicious anemia, methylmalonic acidosis