Why eating tryptophan-rich foods may not increase brain serotonin

Hi,

I will continue on the note of last week.  Tryptophan, as I said earlier, is one of the 14 essential amino acids (building blocks of proteins) we need to get through food. (Examples of  other essential amino acids are Tyrosine, Phenylanine, Valine, Leucine, Isoleucine, Taurine, Glutamine, Alanine and Asparagnine etc)  

Tryptophan is especially essential for migraineurs as they form the raw material for serotonin – the key player in migraine occurence and prevention. Unlike most of the other essential amino acids, tryptophan has large molecular structure (as shown in my last post). Such large molecules are not allowed through the blood-brain barrier.  

We must understand that tryptophan is required in only trace quantities by the body. The RDA value for it is set at 0.2 grams. Our meals on an average provide us anything between 1 to 1.5 grams every day. Yet only a small fraction of it reaches our brain where it is needed most. Let us see how the scarce tryptophan can play truant in the various stages of it’s metabolisation:

Stage #1: Tryptophan is first broken down by the enzyme Tryptophan Hydroxylase with the help of Vitamin B3 (or Niacinamide) into 5HTP. Here is Catch #1: It might so happen that you are deficient in Vitamin B3, which will spin into action a whole new string of events in the body. When the liver encounters the dietary tryptophan in the absence of adequate levels of Vitamin B3, it will use the scarce tryptophan to manufacture Vitamin B3. It does so at a very steep ratio of  60mg of tryptophan to produce 1mg of Vitamin B3!!

Stage # 2: Here, another enzyme called Decarboxylase converts 5HTP to 5HT with the help of Vitamin B6. Catch # 2: In the liver, tryptophan is metabolised using the enzyme tryptophan pyrrolase. However, if you are even mildly deficient in Vitamin B6, this tryptophan will be converted to toxic metabolites such as hydroxikynurenine, xanthurenic acid and hydroxyanthranilic acid, by the liver. 

Now assuming that tryptophan was successfully converted to the 5HT compound without being lost as Vitamin B3 or toxin metabolites or both, it now faces competition with 5 other amino acids (tyrosine, valine, leucine, isoleucine and phenylanine) to reach the blood-brain barrier. 5HT is carried to the barrier through carbohydrate transport molecules. What can be done at this stage, is to make more carbohydrate available so that the chances of tryptophan transportation increase. A migraineur’s preference should be a mild increase in the intake of complex carbs (wholemeal grains, cereals, lentils, pulses etc). This makes free buses available to carry the tryptophan to the brain.

Crossing the blood brain barrier and reaching the Central Nervous System, 5HT is converted to serotonin. 

Doctors prescribe 5HTP supplements as they have better chances to convert to serotonin than tryptophan supplements. It is generally also prescribed with a low dose of Vitamin B3 and B6. The indicative doses are generally in the range of 1 -3 grams of tryptophan, 100 mg of B3 and 25 mg of Vitamin B6.  Consult your doctor before taking them.

Next week I shall touch upon the importance of serotonin and how it helps alleviate symptoms of disturbed sleep, depression etc in migraineurs.

Until then, take care.

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