Sisu 5-HTP - A metabolite of the amino acid tryptophan. Proteins in the food we eat provide us with amino acids. One of those amino acids is tryptophan. Tryptophan is broken down by vitamins, enzymes and other co-factors, into 5-HTP and then 5-HTP is turned into serotonin. Serotonin is the neurotransmitter that tells your brain that you are satisfied and do not need to eat anymore. Serotonin deficiency contributes to weight gain, anxiety, sleeplessness and other symptoms. Low serotonin levels also lead to carbohydrate cravings (sugar cravings) and overeating. 5-HTP can help reduce appetite, while it also can enhance your mood, and increase your energy levels.