B-6 & 5-HTP

Vitamin B-6, or pyridoxine, is a member of the B complex family. Like all B vitamins, pyridoxine is water-soluble, so dietary excesses are readily eliminated in your urine. Once inside your body, pyridoxine is converted to its active form, pyridoxal-5-phosphate. P5P serves as a cofactor for about 100 enzymes in your cells, and participates in the metabolism of several neurotransmitters, including dopamine, norepinephrine and serotonin. P5P plays a particularly important role in converting 5-hydroxytryptophan (5-HTP) to serotonin.

Serotonin

Neurotransmitters are chemical messengers that relay electrical impulses from neuron to neuron within your nervous system, and many act as neurohormones or signaling molecules for other processes. According to an issue of the "Journal of Psychopharmacology" published in March 1998, serotonin modulates your moods, emotions, sleep cycles and appetite. Thus, serotonin has been a principal target for medications designed to treat depression, anxiety and obesity. Vitamin B-6 and 5-HTP are intimately involved in regulating serotonin levels in your body.

Synthesis

Serotonin is synthesized in a two-stage process that requires a different enzyme for each step. L-tryptophan -- an amino acid found in meats, eggs, dairy products, nuts and seeds -- is initially converted to 5-HTP by the enzyme tryptophan hydroxylase. Then, 5-HTP is subsequently converted to serotonin by the amino acid decarboxylase, an enzyme that requires P5P for its proper function. Without sufficient "fuel" for this pathway -- either L-tryptophan or 5-HTP and vitamin B-6 -- serotonin synthesis is impaired.

Recommendations

Recommended dietary allowances for vitamin B-6 -- the doses needed to avoid deficiency -- vary from 100 mcg daily for infants to 2 mg for nursing mothers. Dr. Elson Haas, author of "Staying Healthy with Nutrition," states that vitamin B-6 doses of 50 to 100 mg daily are well tolerated and safe for adults. Typical adult doses of 5-HTP vary from 50 to 200 mg. You can take both vitamin B-6 and 5-HTP in single doses, or you can divide them into two or three daily doses.

Considerations

Vitamin B-6 and 5-HTP are essential ingredients in the synthesis of serotonin, an important neurotransmitter and neurohormone in your brain, bloodstream and gastrointestinal tract. Your body can manufacture serotonin from L-tryptophan via a two-step enzymatic pathway, or it can produce it more directly using 5-HTP, a process that involves a vitamin B-6-dependent enzyme. Increasing your brain's serotonin levels may help combat depression, anxiety, insomnia or even some eating disorders, but check with your doctor before using 5-HTP for any medical condition, especially if you are already taking medications.