As human beings, we don't synthesize most of the co-enzymes we need. We get them from our diet in the form of vitamins, which each have a series of metabolic processes (chemical reactions) that take place before becoming a co-enzyme, such as co-enzyme A or the well known molecule NAD.
The following table provides a summary of select B vitamins, which should not be used as a basis for any therapeutic or medical use - consult a health care professional for such advice.
VITAMIN | 
COENZYME | 
TYPICAL REACTION TYPE | 
CONSEQUENCES OF DEFICIENCY | 
 
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 Molecule(B7) | 
Biotin-lysine adducts (biocytin) | ATP-dependent carboxylation and carboxyl-group transfer | Rash about the eyebrows, muscle pain, fatigue (rate) | 
 
Folic acid (B9) | 
Tetrahydrofolate | Transfer of one-carbon components thymine systhesis | Anemia, neural-tube defects in development | 
 
B12 | 
5'-Deoxyadensosyl cobalamin | Transfer of methyl groups; intramolecular rearrangements | Anemia, pernicious anemia, methylmalonic acidosis | 
Chemicals Drawn With

Thiamine (B1)
Riboflavin (B2)
Pyridoxine (B6)
Nicotinic acid (niacin) (B3)
Pantothenic acid (B5)
Biotin Molecule(B7)
Folic acid (B9)
B12