Tryptophan is an amino acid discovered by two British biochemists, Hopkins and Cole, in the early 1900s and is one of the eight amino acids defined essential, that is that they are not produced by the body but have to be introduced with diet (Richard et al, Int J Tryptophan Res, 2009).
Tryptophan, what is it?
Tryptophan is used by the brain to produce serotonin. Serotonin, in turn, is a neurotransmitter involved in various processes such as sleep induction, pain threshold control, thermoregulation, hunger and mood. This is why low levels of tryptophan are associated with insomnia, depression but also anxiety. A research (Lindseth et al, Arch Psychiatr Nurs, 2016) has just shown how a diet with a high intake of tryptophan followed for four days was able to improve mood and to reduce symptoms of depression compared to those who had followed a diet with a low tryptophan intake. People of the latter group, moreover, were even more irritable and anxious. Not only that, scientific studies have also demonstrated the essential role of tryptophan in ensuring a correct functionality of the intestine brain axis, that is the system that connects the brain and the gastrointestinal tract so that changes of the microbiome, namely the intestinal bacterial flora, can cause disorders of the central nervous system, but tryptophan also plays a role in determining the health of the cardiovascular system and of the immune system (Kaluzna-Czaplinska et al, Food Rev Nutrition Crit., 2019 - Friedman et al, Int J Tryptophan Res, 2018 - Jenkins et al, Nutrients, 2016). That's why a proper intake of tryptophan through diet is important.
Tryptophan, daily requirement and food sources
The daily intake of tryptophan for adults is set between 250 and 450 mg per day. Possible food sources of tryptophan are oats, bananas, prunes, milk, cheeses, bread, chicken, turkey, lean fish, chocolate and peanuts.
Tryptophan and supplements
As reported by the University of Rochester Medical Center, it is preferable to take tryptophan through the diet and avoid the use of supplements unless they are prescribed or recommended by the doctor as these could cause health problems, such as gastrointestinal problems, diarrhea, loss of appetite, headache and fatigue.