5-HTP, a close relative of tryptophan, is being taken as a substitute for it. Its potential dangers outweigh any possible benefits.
Neurotransmitters play a complex role in the brain and nervous system.
But the brain makes its supplies of neurotransmitters mostly from amino acids, the building blocks of protein, and these do enter the brain from the bloodstream. For example, the amino acid tryptophan is converted into that important neurotransmitter serotonin. Thus, for years people took tryptophan pills to treat insomnia and as a mood modifier, with some success. Then in 1989 an outbreak of a rare and incurable blood disease among thousands of people taking tryptophan led the FDA to ban all sales of the pills. At least 38 people died, and most of the other victims have remained crippled with painful nerve damage, severe joint pain, and scarring of internal organs.