1. Yeast cells digest food to obtain energy for growth. Their favorite food is sugar in its various forms: sucrose (beet or cane sugar), fructose and glucose (found in honey, molasses, maple syrup and fruit), and maltose (derived from starch in flour).
2. Yeast metabolism produces compounds derived from tryptophan, which are found in fermented beverages, such as wine and beer. In particular, melatonin and serotonin, may be relevant due to their bioactivity in humans.
3. Serotonin is in the brain. It is thought to regulate mood, happiness, and anxiety. Low levels of serotonin are linked to depression, while increased levels of the hormone may decrease arousal.
