 When people think tryptophan, they think Thanksgiving turkey and warm milk. But researchers in MIT dispelled those myths about a decade ago. Tryptophan is one amino acid among many found in proteins, and they all compete with one another for transport across the blood-brain barrier into the brain. And since tryptophan is present in most animal proteins in relatively small quantities, it gets muscled out of the way. The plant foods, though, the carbohydrates cause a release of insulin, which causes your muscles to take up the non-tryptophan amino acids as fuel, and so your tryptophan can be first in line for brain access. Animal foods can even make things worse. When tryptophan is ingested as part of a protein meal, serum tryptophan levels rise, but brain tryptophan levels decline due to the mechanism of transport used by tryptophan to cross the blood-brain barrier. The tryptophan levels in those given a high protein turkey egg cheese breakfast dropped, whereas in the waffle OJ group, their tryptophan levels went up. This may actually explain the carbohydrate cravings one sees in PMS. Your brain may be trying to get you to boost tryptophan levels to feel better. Consumption of a carbohydrate-rich protein-poor evening meal during the premenstrual period improved depression, tension, anger, confusion, sadness, fatigue, alertness, and common scores significantly among patients with premenstrual syndrome. Because synthesis of brain serotonin, which is known to be involved in mood and appetite, increases after carbohydrate intake when premenstrual syndrome subjects may over-consume carbohydrates in an attempt to improve their dysphoric mood state. Ideally, though, it'd be more than just carbs. We'll cover the ideal mixture in tomorrow's video of the day.