tryptophan

Etymology

From German Tryptophan, from Ancient Greek φαίνω (phaínō, “to appear”).

noun

1. (biochemistry) An essential amino acid having an indole side chain; it is present in many foods, especially chocolate, oats, bananas and milk; it is essential for normal growth and development and is the precursor of serotonin and niacin; any specific form of this compound, or any derivative of it.
   The quickest way to raise serotonin levels again is to send more tryptophan into the brain, because serotonin is made from tryptophan. 1999, Matt Ridley, Genome, Harper Perennial, published 2004, page 169
   Tryptophan is an amino acid found in many foods, including dairy and turkey, which is one of the reasons commonly given for why so many of us feel so sleepy after our Thanksgiving feasts. 2020-12-10, Anahad O’Connor, “How Foods May Affect Our Sleep”, in The New York Times, →ISSN