Reducing One Amino Acid Could Increase Lifespan
John Bryson writes "Eating less of one amino acid might lengthen your life. There have been lots of previous studies showing that many species live long on highly restricted calories, but a lot of this benefit may be possible by only restricting one amino acid. Amino acids that have shown this have been tryptophan and methionine. A recent study, published online December 2 in Nature, a highly respected journal, may help explain some of the health benefits of restricted-calorie diets."
RTFA indeed, if you read as far as the third paragraph you'd know that it was also proven on mice, dogs, and baboons. That makes this pretty likely to apply to humans as well. Though I'm confused as to why the summary says that tryptophan also has this property, as the article doesn't even use the word. I couldn't find the original Nature article, but the linked one certainly said nothing about it.
Quidquid latine dictum sit, altum videtur.