Tryptophan

What's this

Tryptophan is an essential amino acid for the human body.

Foods rich in Tryptophan

Given our inability to synthesize it independently, tryptophan must be taken through food; legumes, meat, fish, dairy products and eggs are rich.

Particularly well known for its high tryptophan content are chocolate, peanuts, milk, cheese, yogurt, ricotta, spirulina algae and sesame seeds.

requirement

The daily requirement in adults is estimated at 3-3.5 mg / kg. Given that there are 560 mg in 100 grams of Parmesan and 240 mg in a 100 pound chicken, just to name a few, the dietary intake of tryptophan is normally higher than the requirement.

Functions

In addition to being a key amino acid in protein synthesis, tryptophan is the starting point for the synthesis of some biological substances, such as serotonin and niacin.

Serotonin is a substantially excitatory neurotransmitter, synthesized through a metabolic pathway called tryptophan hydroxylase (from the name of an enzyme involved in this pathway). Also known as "good mood hormone", serotonin can be converted into melatonin, which is very important in regulating the sleep-wake cycle.

Niacin, better known as vitamin PP, is involved in cellular metabolisms that convert macronutrients into energy; approximately 3.3% of the food tryptophan is destined for the synthesis of niacin.

Tryptophan supplements

Its amino acid as a supplement is substantially due to its already mentioned role in the synthesis of serotonin.

Tryptophan levels in the blood are particularly low in lactose intolerant people (remember that dairy products are particularly rich in tryptophan) or with fructose absorption disorders.

On the other hand, serotonin levels are often decreased in depressed patients, who not by chance are frequently treated with drugs "selective inhibitors of the reabsorption of serotonin" (fluoxetine, sertraline, citalopram, escitalopram, fluvoxamine, paroxetine). These medicines act at the level of cerebral synapses (spaces intended for nerve transmission between two neurons), preventing the normal re-uptake and physiological elimination of serotonin (the proportion reabsorbed by the presynaptic terminal is processed by monoamine oxidases, which oxidize serotonin, then transformed into 5-hydroxyindoleacetic acid excreted in the urine). Thanks to these active principles, the higher levels of serotonin available to postsynaptic receptors can rebalance the disorders generated by its possible deficiency, such as those associated with obsessive-compulsive disorder or major depression.

SEROTONIN SYNTHESIS starting from tryptophan involves two different enzymes, called triprofan hydroxylase and amino acid decarboxylase. In the first stage the tryptophan is converted into 5-hydroxytryptophan, thanks to the action of tryptophan-hydroxylase; then the 5-hydroxytryptophan is decarboxylated to serotonin, by the amino acid decarboxylase.

Precursor: the amino acid tryptophan
conversion to 5-hydroxytryptophan by the enzyme tryptophan-hydroxylase
5-hydroxytryptophan is decarboxylated to 5-HT, by the decarboxylase of aromatic amino acids

5-hydroxytryptophan supplements

The limiting factor of this biological process lies in the activity of the enzyme tryptophan hydroxylase, which is why it is preferred to resort to the integration not so much of tryptophan itself, as of the product of this enzyme: 5-hydroxytryptophan, present in food in quantities negligible. This amino acid derivative, capable of crossing the blood-brain barrier, is proposed as an antidepressant, a valid aid against insomnia and anorectics (inhibitor of appetite, in particular the immoderate need for sweets).

Although it has been shown to be effective in increasing serotonin and melatonin levels in the body, the use of a 5-hydroxytryptophan supplement cannot replace the classic antidepressant or hypnotic therapies, which - although with inevitable side effects - ensure an effective therapeutic action. The reader is therefore advised NOT to spontaneously substitute classic pharmacological therapy with 5-hydroxytryptophan-based supplements, nor to take them together with antidepressant drugs (unless otherwise prescribed by a doctor).

Furthermore, 5-hydroxytryptophan can be converted to serotonin directly in the liver and this significantly increases the risk of cardiac valve dysfunction (effect demonstrated in animal models by direct administration of serotonin).