HealthyPIG Magazine

Bananas indirectly contain serotonin by providing the amino acid tryptophan. Tryptophan is an essential amino acid that is a precursor to serotonin...

Tryptophan is an essential amino acid used to make proteins. Your body can't make it, so you need to get it from your diet. Foods containing tryptophan include animal products such as chicken and fish and plant foods such as nuts or soybeans.
When we eat tryptophan, our body converts part of it into 5-HTP, which is then converted into the neurotransmitter serotonin. The body also converts some tryptophan into nicotinic acid adenine dinucleotide (NAD), which is why tryptophan is also considered a dietary source of niacin.
There are two types of tryptophan: L-tryptophan and D-tryptophan. The only difference between the two types is the orientation of the molecules.
You can get tryptophan through certain foods or supplements in powder form.