Tryptophan is the lowest essential amino acid in corn, many cereal grains, and legumes. The dietary intake of tryptophan in general is lower than most other amino acids. It is not particularly high in any foods but is readily available in flesh foods, eggs, dairy products, and some nuts and seeds. It is present in the casein component of milk.
Functionally, tryptophan is very important, and it has been used effectively for a variety of medical problems. Vitamin B6, vitamin C, folic acid, and magnesium are needed to metabolize tryptophan. It is the precursor for a vital neurotransmitter, serotonin, which influences moods and sleep, and serotonin levels are directly related to tryptophan intake. As other amino acids, such as tyrosine and phenylalanine, compete for absorption with tryptophan, tryptophan must often be taken as a supplement to increase its blood levels. It also acts differently than other amino acids, as it can exist free in the blood and can be carried by protein. In a sense tryptophan is really an essential vitamin since it is the precursor of vitamin B3 (niacin); a deficiency of tryptophan, combined with inadequate dietary niacin, can cause the symptoms of pellagra: dermatitis, diarrhea, dementia, and death (the four D's; see the section on Niacin in Chapter 5, Vitamins). Low tryptophan levels are found in many patients with dementia and may have subclinical or subtle psychological effects.
Tryptophan has been used effectively to treat insomnia in many people. Serotonin is needed in the brain to induce and maintain sleep. Usually, 1–2 grams of L-tryptophan (the desired form) are needed to increase blood levels sufficiently to induce sleep. However, the lowest dose that works to aid sleep (often as little as 500 mg.) should be maintained. It can be repeated if the person wakes in the middle of the night. As an initial treatment, I suggest 1 gram of L-tryptophan taken 30–45 minutes before bed, which reduces the time it takes to fall asleep (sleep latency period). Some formulas contain vitamin B6 and niacinamide, which improve tryptophan utilization. If 1 gram is insufficient, increase the dose 500 mg. each night, up to a total of 3000 mg., and add calcium, 300–600 mg., and magnesium, 200–400 mg., to your good-night supplements.
Tryptophan works better for acute insomnia than for chronic sleep problems. Patients with asthma or systemic lupus erythematosus should not take tryptophan. Generally, side effects are negligible, and tryptophan does not distort sleep patterns until more than 10 grams are taken. Occasionally, some morning sluggishness may occur.
Tryptophan also has an antidepressant effect and is particularly effective in manic depression and depression associated with menopause. Many depressed patients have low levels of tryptophan. Tryptophan can be a useful and safe pain reliever. It has been shown most helpful for dental pain, headaches (migraines in particular), and cancer pain, often in conjunction with aspirin or acetaminophen. Tryptophan appears to increase the pain threshold. It may help treat anorexia by increasing the appetite. Since it is the precursor of niacin, tryptophan supplementation may help to lower cholesterol and blood fat levels. Other possible uses for L-tryptophan include parkinsonism, epilepsy, and schizophrenia, and with further research, we may find this important amino acid may provide help in other medical conditions.