5-HTP is aminotransmitter precursor used by the brain to synthesize serotonin. Serotonin is a nervous system messenger, also called a neurotransmitter, with many functions in the body. One of those functions is that it can help to reduce appetite. In fact, in the pharmaceutical market, the role of serotonin in appetite control and satiety (which means the state of being satisfactorily full and unable to eat more) is well established, and is the basis for selective serotonin reuptake inhibitor (SSRI) medications, which increase serotonin levels and help reduce food intake.
5-HTP and Depression
The causes of depression are multiple and varied, with low levels of the neurotransmitter Serotonin in the brain being one potential cause.
Serotonin is associated with improved mood and overall behavior. Elevated Serotonin levels have a positive effect on sleep, mood, anxiety, appetite, and even how the body responds to pain.
The amino acid Tryptophan, and consequently 5-HTP, is a precursor to Serotonin. Tryptophan is an essential amino acid, meaning it cannot be produced in the human body. Tryptophan must be obtained through the diet or supplements. Dietary sources of Tryptophan include many protein-rich foods such as turkey, milk, red meat, eggs, green beans, garlic, and chickpeas.
When Tryptophan is broken down in the liver, 5-HTP and other metabolites are produced. Some 5-HTP travels through the bloodstream to the brain. The 5-HTP crosses the barrier separating the bloodstream and the brain.
Once in the brain, 5-HTP is converted into Serotonin. Some Serotonin in the brain is further converted into Melatonin. Melatonin is the main neurotransmitter associated with circadian rhythm (sleep-wake cycles) in the body.
One could use a Tryptophan supplement for depression, mood enhancement, and improved sleep patterns. However, taking 5-HTP directly is often considered more effective since it avoids the unnecessary initial conversion. Serotonin cannot cross the blood-brain barrier, therefore it is ineffective to supplement directly with Serotonin to increase levels in the brain.