[quote="jurplesman
Various coenzymes are needed to complete to conversions.
People with a niacin (B3) deficiency may not be able to produce serotonin, because the body will convert tryptophan into niacin at the rate of 60 to 1, leaving little
tryptophan for conversion to serotonin.
Hence some people may overcome their depression by taking niacin. It is better to take 5-HTP.
In nutritional medicine we need to avoid the temptation to think in terms of
single causes, suggesting that
single remedies can treat depression. Psychiatrist tend to make the same mistake believing that single drugs can "cure" depression. They too underestimate the complexity of nutritional medicine.
Nutritional biochemistry is far too complex for this. Nutrients are dependent on other nutrients and work in cooperation of one another.
See:
Hit or Miss Supplements for Depression[/quote]
http://www.smart-drugs.com/JamesSouth-depression.htm
In people who are even marginally vitamin B6 deficient, Tryptophan may be immediately degraded by the liver into the mildly toxic metabolites hydroxykynurenine, xanthurenic acid, and hydroxyanthranilic acid, then excreted in urine (9). Thus, the brain typically receives less than l% of ingested Tryptophan.
Vitamin b6 is essential for serotonin levels. (Niacin is also important to prevent a NAD deficiency.) But if anyone needs to supplement amino acids like tryptophan or 5htp then there are either not breaking down proteins into amino acids or not eating enough protein. Either situation should be corrected.