"A cheese sandwich is the key to making all difficult decisions!" — truth or fiction? On the one hand, it's true, and on the other hand, it's just a beautiful title that attracts ordinary people (that is, not scientists with a degree). What other stuffing do scientists and journalists pack their articles with in order to attract non-ordinary readers?
And yes, cheese, meat and chocolate do contain tryptophan, which influences decision-making. But only in the experiment itself there was no cheese or chocolate. There was only an unpleasant-tasting drink, but will you read an article with the title "The amino acid tryptophan affects decision-making"? But people have already read about cheese and chocolate and ran to the shops for shopping.
And so it is with almost every study. The human brain still remains an unsolved mystery for scientists. They can only assume about his various reactions to certain stimuli, but no one has managed to get 100% of the evidence yet. And you and I, as people who are used to believing scientists, are left to read, analyze information and question it. The truth is really out there somewhere.