Tryptophan is one of the ?essential? amino acids; ?essential? in this context meaning that it cannot be produced by the body, and must therefore be obtained from dietary sources. The best dietary sources of tryptophan are the animal proteins known as first class proteins because they contain all ten essential amino acids; principally meat, including poultry, fish and dairy produce. Second class proteins are typically obtained from vegetables, grains, nuts and beans, and contain some but not all of the essential amino acids. Taken in appropriate combinations, however, these food types can also help provide the full range of essential amino acids.

As an essential amino acid, tryptophan has an important general role, together with the other twenty or so amino acids which have been identified, in the production of the countless thousands of proteins which form much of the body's tissue. Many of the enzymes which control the countless biochemical reactions which are vital for health are also formed from protein, as are the antibodies that fight disease.

More specifically, there is good evidence that taking tryptophan as an individual amino acid in the form of a dietary supplement may increase the amount of serotonin produced by the body. Serotonin has become popularly known as the ?feel-good hormone?, or the body's own natural tranquiliser, and the body's production of serotonin is very heavily dependent on its intake of tryptophan.

The fact that tryptophan is the most organically complex of the amino acids makes it the most expensive to obtain in supplement form, but the importance of serotonin to health, particularly mental health, may nevertheless make it well worth considering in certain circumstances.

Good levels of serotonin are also required for the production of melatonin, the hormone which is principally responsible for the maintenance of regular cycles of sleep and wakefulness, and consequently has a profound effect on overall health. Tryptophan (or 5 hydroxy-tryptophan) has therefore been commonly recommended for those suffering from insomnia and other sleep disturbances, but it has also been used to tackle a range of conditions including depression, anxiety and panic attacks, migraine, obsessive compulsive and attention deficit disorders, social phobias, eating disorders and even autism.

Perhaps most excitement, however, has been generated by tryptophan's apparent role in controlling the appetite. Serotonin is known to be secreted on the digestion of carbohydrate, helping to produce that feeling of satisfaction and fullness following a meal which is an important signal to the body to stop eating. There is some evidence, therefore, that supplements of tryptophan may help with weight loss for those following reduced calorie control programs by reducing the sensation of hunger; in effect by tricking the body into believing it is fuller than it actually is.

Supplements are normally taken in three doses totalling between 150 ? 300 mg a day, preferably taken on an empty stomach. Side effects are only very rarely seen at such levels, and have been confined to minor digestive upsets and headaches. Such supplementation should not be continued for too long, however, because amino acids operate in a complementary manner, and their proper functioning may be disturbed if an imbalance is created through single supplements. It is therefore not recommended that any supplementation with tryptophan should be continued for longer than three months, and it should be avoided in any case during pregnancy and while taking anti-depressant drugs. Tryptophan may also cause drowsiness and so is also contra-indicated for use when high levels of alertness are required, eg whilst driving. And, as always, the holistic nature of the body's functioning should be stressed; meaning that amino acids, including tryptophan, are no different from any nutrient or supplement in that they will perform correctly only when at least adequate amounts of all the nutrients needed by the body are present.

So if taking supplements of tryptophan, you should ensure that you continue to include good supplies of high quality protein foods in your diet; and for maximum absorption and optimum effect these should be taken with plentiful quantities, including supplements if necessary, of all necessary vitamins and minerals. But in the case of tryptophan, in particular, it appears that vitamin B6 and vitamin C are especially important, and in precise proportions, if serotonin is to be released, and that 1,000 mg of vitamin C and 100 mg of B6 are required for each 2,000 mg of tryptophan.