Vitamin D in Autism – too much or too little?

Reader’s of this blog will be aware that serotonin plays a major role in autism, and also in many other mental health conditions, like depression.

Vitamin D also regularly raises its head in discussions about autism.  You may recall the Somali autism clusters in Sweden and Minneapolis; researchers suggested that the Somali immigrants were not getting enough sun and therefore lacked vitamin D and so produced children with autism.  I did point out that another large Somali autism cluster exists in sun-drenched San Diego.

Even Martha Herbert talks about vitamin D deficiency and autism.

A while back we had a guest blogger, Seth Bittker, present his opposing view, that too much vitamin D added to food in the American diet may be contributing to the rise in autism there.

In same week that Seth has published his paper on this subject, yet another paper has appeared with the opposing view.  So who is right?

The case for (even) more Vitamin D

The first paper is:- 

Vitamin D hormone regulates serotonin synthesis. Part 1:relevance for autism

 

The authors make the following case:-

Serotonin and vitamin D have been proposed to play a role in autism, however, no causal mechanism has been established. Now, researchers show that serotonin, oxytocin, and vasopressin, three brain hormones that affect social behavior related to autism, are all activated by vitamin D hormone. Supplementation with vitamin D and tryptophan would be a practical and affordable solution to help prevent autism and possibly ameliorate some symptoms of the disorder.

After absorbing L-tryptophan from food, our bodies convert it to 5-HTP (5-hyrdoxytryptophan), and then to serotonin.

The supplements L-tryptophan and 5-HTP are widely available and have been used in ADHD and autism but there is no evidence that they are effective.  All that has been shown is that too little tryptophan is bad; there is nothing to show that abnormally large amounts do any good.

If you read the full paper there is an excellent explanation of the role of serotonin in autism.  It is beyond doubt that in many kids with ASD there is high blood serotonin, but low brain serotonin.

To fully treat autism, one thing to be done is to raise brain serotonin levels, without any nasty side effects.  SSRI drugs like Prozac, used to treat depression, do raise brain serotonin but often cause dependence and side effects (like suicidal thought).

It would be great if some vitamin D and tryptophan could do the job.

If you read the older literature, you will see that there is nothing new about the idea to supplement with Tryptophan in autism.  The results to date have been nothing special.

Here is a paper by Paul Whiteley and Paul Shattock:-
 

Effects of Supplementation with Tryptophan and derivatives.  

“It has been shown that a diet depleted of tryptophan is not beneficial for children with ASDs and that some symptoms are exacerbated. Presumably, the existing lack of available serotonin (and other tryptophan derivatives) was exacerbated under these circumstances. Supplementation with tryptophan would probably not be helpful in the majority of cases because the conversions along the important pathways are inhibited and tryptophan is likely to be converted along the IAG route, which would be unhelpful. Anecdotal clinical reports suggest that some children show benefits and others may get worse but no formal studies have been reported.

For this reason, and because tryptophan is a prescription-only drug*, we have looked at other methodologies. The active transmitter, serotonin, does not cross the blood brain barrier and so would be ineffectual in this respect. However, the precursor molecule 5-HTP does cross the blood brain barrier and reach the appropriate target areas. Some parents have reported impressive consequences, particularly with regard to sleep patterns; some physicians have been able to reduce the doses of e.g. risperidone (an anti-psychotic drug) by supplementing 5-HTP but, on the whole, the results have been less useful than would have been predicted.”

Vitamin D and Children with ASD

Children with autism are probably amongst the most “vitamin-supplemented” of any, since parents tend to give copious amounts of multi-vitamins and also vitamin D rich omega 3 fish oil.  It is hard to imagine that any of these children are deficient in vitamin D.

 

The case for too much vitamin D

In his paper, Bittker seeks to correlate the increase in vitamin D fortification in America with the rise in autism; he highlights groups that do not have vitamin D fortified food and where autism is far less prevalent.

Infant Exposure to Excessive Vitamin D: A Risk Factor for Autism

 

Conclusion

So who is right?  Well for sure too little tryptophan or vitamin D is bad for you; but are abnormally high levels good or bad?  In the case of tryptophan, plenty of people have tried supplementation in autism and ADHD and we would probably have heard if it produced a great effect.

Do large amounts of vitamin D help with autism? I very much doubt it, but it would be very easy to do a trial, assuming you found some parents who had not read the Bittker paper.

The good thing is that raising the low level of brain serotonin seems agreed by everyone as a prime target of any autism intervention. For me, vitamin D and tryptophan is not the answer.