PINEAPPLES, BLUEBERRIES, AND CHERRIES First, I want to talk about fruits. Especially pineapples, cherries, and blueberries. Pineapples are a great source of the amino acid tryptophan. Tryptophan is a precursor of the “happy hormones” serotonin. When serotonin is at normal levels, you feel more focused, emotionally stable, happier, and calmer. …