Tryptophan is an essential amino acid and is needed to maintain optimum health. Tryptophan must be obtained from the diet. The unusual indole side chain of tryptophan is also the nucleus of the important neurotransmitter serotonin, which is biosynthesized from tryptophan. The aromatic portion of tryptophan also serves as an ultraviolet marker for detection of this amino acid either separately, or incorporated into proteins and enzymes, via ultraviolet spectrophotometry. Tryptophan is incorporated into proteins and enzymes at the molar rate of 1.1 percent compared to other amino acids, making it the rarest amino acid found in proteins.

Tryptophan is required for the production of niacin (vitamin B3). It is used by the human body to produce serotonin, a neurotransmitter that is important for normal nerve and brain function. Serotonin is important in sleep, stabilizing emotional moods, pain control, inflammation, intestinal peristalsis, etc.

It is further important in controlling hyperactivity in children, assists in alleviating stress, helps with weight loss and reducing appetite. It has been found that people suffering from migraine headaches have abnormal levels of tryptophan. In this case, supplementation may be helpful.

A shortage of tryptophan, combined with a shortage of magnesium, may be a contributing factor to heart artery spasms.

Supplementation with high dosage of Tryptophan could lead to gastrointestinal upsets, headaches, sleepiness and anxiety.

Good dietary sources for this amino acid are cottage cheese, meat, soy protein and peanuts.