Although purified tryptophan increases brain serotonin, foods containing tryptophan do not. This is because tryptophan is transported into the brain by a transport system that is active toward all the large neutral amino acids and tryptophan is the least abundant amino acid in protein. There is competition between the various amino acids for the transport system, so after the ingestion of a meal containing protein, the rise in the plasma level of the other large neutral amino acids will prevent the rise in plasma tryptophan from increasing brain tryptophan. The idea, common in popular culture, that a high-protein food such as turkey will raise brain tryptophan and serotonin is, unfortunately, false. Another popular myth that is widespread on the Internet is that bananas improve mood because of their serotonin content. Although it is true that bananas contain serotonin, it does not cross the blood–brain barrier.
Source.
Bookmarks