tryptophan
Americannoun
noun
Etymology
Origin of tryptophan
1900–05; trypto- (irregular combining form representing Greek trīptós “rubbed”) + -phan(e) ( def. )
Explanation
Tryptophan is an amino acid that humans need in their diets in order to be healthy. Meat is known for providing lots of tryptophan. You may be familiar with tryptophan as the chemical present in turkey that is supposed to make people feel like taking a nap after their Thanksgiving feasts. In reality, scientists suspect that carbohydrates and alcohol — as well as overeating — are the true culprits in post-feast sleepiness. Tryptophan is important, though, since it helps our bodies synthesize the protein that we eat.
Example Sentences
Examples are provided to illustrate real-world usage of words in context. Any opinions expressed do not reflect the views of Dictionary.com.
The nutrients are involved in converting tryptophan into the sleep-promoting hormone melatonin, she said.
From The Wall Street Journal ● Dec. 29, 2025
No—they’re football tryptophan, a snoozy bore to watch.
From The Wall Street Journal ● Nov. 24, 2025
Both of these behavioral changes stemmed from altered tryptophan metabolism.
From Science Daily ● Nov. 13, 2025
The research reveals how dietary tryptophan -- an amino acid found mostly in animal products, nuts, seeds, whole grains and legumes -- can be broken down by gut bacteria into small molecules called metabolites.
From Science Daily ● Mar. 13, 2024
Maize lacks digestible niacin, the amino acids lysine and tryptophan, necessary to make proteins and diets with too much maize can lead to protein deficiency and pellagra, a disease caused by lack of niacin.
From "1491" by Charles C. Mann
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