L-Tryptophan- Tryptophan is an essential amino acid as well as within the group of only twenty standard amino acids that are required by the human diet. It is one of the building blocks required for protein biosynthesis. It is also viewed as a precursor to serotonin and thereby also melatonin, niacin and also auxin. Interestingly enough, lactose intolerance and fructose malabsorption have the side effect that tryptophan is only improperly absorbed in the intestines which leads to diminished levels of it in the system. Dietary sources of tryptophan are plentiful, it can be found in red meat, poultry, fish, milk, milk products, peanuts, mangoes, dates, chocolate and oats, among others. As a dietary supplement tryptophan has found applications as a safe sleeping aid and also as a calming agent.