Serotonin

Serotonin is the messenger for mood, emotional stability, sleep and satiety. 95 % of serotonin is produced in the gut – not in the brain. Its precursor is tryptophan; the conversion needs vitamin B6, iron and BH4; daylight influences serotonin turnover in the brain. Chronic intestinal inflammation and dysbiosis act on serotonin production.

How serotonin acts in the body

Serotonin is made from the amino acid tryptophan: tryptophan hydroxylase forms 5-hydroxytryptophan (it needs BH4 and iron for this), and the decarboxylase with vitamin B6 turns it into serotonin. Most of it is produced in the gut lining, where it stimulates gut movement and secretion; platelets take it up and release it at injuries. Because serotonin does not cross the blood-brain barrier, the brain makes its own – there it acts via many receptor types on mood, the sleep-wake rhythm, appetite and pain processing. At night part of it becomes melatonin.

Low serotonin – what happens in the body?

When little serotonin is available, gut movement is stimulated less, and the brain lacks signals that help regulate mood, impulse control, satiety and sleep; in the evening less starting material for melatonin is available. Causes are little tryptophan, too little of the helpers vitamin B6, iron or BH4, and increased tryptophan breakdown via the kynurenine pathway, for example with inflammation.

High serotonin – what happens in the body?

A lot of serotonin in the gut speeds up gut movement (diarrhoea, cramps). In the nervous system, a marked excess – usually from combining several serotonin-enhancing medications – can cause restlessness, sweating, muscle twitching and racing heart; this requires immediate medical attention.

The interpretation is given in your report.