What makes Serotonin?

As serotonin is so important to help us feel good and levels are low in those with seasonal affective disorder, what can we do to help increase our levels.

Low levels of serotonin in the brain are thought to be one of the causes of seasonal affective disorder and symptoms are often treated by trying to raise the levels of this feel-good brain chemical. But what makes serotonin in our brain?  Can't we just supplement our levels with serotonin medication?

Unfortunately serotonin can't be taken as a supplement as it fails to pass from our digestive systems and blood stream to our brain. That's because of the blood-brain barrier designed to stop harmful chemicals reaching our brain.  In doing its job, this useful mechanism also screens out some beneficial chemicals too.

Serotonin has to be manufactured by the brain itself using the amino acid tryptophan. Tryptophan is transported to the brain along with five other amino acids: leucine, isoleucine, valine, tyrosine and phenylalanine. And this can create a bottleneck in getting tryptophan to the brain as the other amino acids are in larger supply in our typical diet than tryptophan (about 8 to 1). This means they tend to get more than their fair share of the transport mechanism. Result : low levels of serotonin.

By eating sweet and starchy food, insulin levels spike (to regulate the sudden rush of glucose to the blood) and this has a side effect of reducing the levels of other amino acids in the blood, giving tryptophan quick access to the brain and increasing serotonin levels. 

All would be well if it were not for the fact that the insulin has the effect of promoting the conversion of the amino acids (plus glucose and fats) it removes from the blood to be stored as fat. Typical sufferers of seasonal affective disorder can put on 10 to 30lbs in weight in the winter.

Tryptophan itself was available as a supplement at one time but it has been withdrawn from sale due to safety issues.  The latest supplement to be used is called L-5-Hydroxytryptophan (5-HTP) and appears to have fewer causes for concern but discuss this supplement with  your doctor if you wish to try it.

Recent studies have shown that bright light also increases the level of serotonin in the brain. This is reflected in the benefits found using light therapy treatment by the majority of patients with seasonal affective disorder. But little is yet known about exactly how daylight increases serotonin levels.

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