November 27, 2010

Carbidopa and 5-HTP mixed messages

If when contemplating 5-HTP you do what I did and check it out on Google to see if there are safety concerns, you find that the most oft-cited concern is about mixing 5-HTP with carbidopa.  Since Carbidopa/Levodopa is the "gold medal" med for treating Parkinson's, this concern would seem to make it advisable to forget about 5-HTP, particularly since the numerous mentions made it appear that a number of studies had led to this concern.

However, when I checked into it further, I found that virtually every website that expressed a caution about this used exactly the same words: 
 “A scleroderma-like skin condition has been reported in some taking a combination of 5-HTP and carbidopa."

I began  to suspect that everybody was quoting each other.

Then I went to PubMed, the service of the US National Library of Medicine that includes over 19 million citations from MEDLINE and other life science journals, and searched for "5-HTP and carbidopa and scheroderma" This produced 7 hits.  But in examining them, it appeared that the 6 most recent reports were on unrelated studies that happened to cite  the 7th study -- a 1980 study in France that was published in the New England Journal of Medicine  and involved 15 people.   The published abstract provided a very thin basis for all of the subsequent cautions.  See:

It's amazing that one small study in 1980 can generate a web-full of warnings.  Meanwhile thousands, if not millions, of people have used 5-HTP without any current reports of this condition. Europeans have been using 5-HTP much longer and more frequently than in the U.S.  AND in Europe it is recommended that 5-HTP be taken WITH carbidopa.

Here's what the Wikipedia entry on Carbidopa has to say:

"Carbidopa is also used in combination with 5-HTP, a naturally occurring amino acid which is a precursor to the neurotransmitter serotonin and an intermediate in tryptophan metabolism. Carbidopa prevents 5-HTP's metabolism in the liver and the resulting elevated levels of serotonin in the blood. Research shows that co-administration of 5-HTP and carbidopa greatly increases plasma 5-HTP levels. 5-HTP has no reported cases of heart valve disease associated with it as found in the peer reviewed literature. [2][3] In Europe, 5-HTP is prescribed with carbidopa to prevent the conversion of 5-HTP into serotonin until it reaches the brain.[4]"


Anonymous said...

Dear John,

My father just got a diagnos where they suspect Parkinson. I try to understand the interaction of the medicines in all common cures for this decease.

I read at wikipedia ( that 5-HTP together with carbidopa causes nausea and vomiting.

Have you ever had these problems ?

Anonymous said...

This article is interesting since it says 5-HTP combined with B6 is better than 5-HTP combined with carbidopa and reduced b6 which some people advocate.

John Schappi said...

Replying to Anonymous, I've not experienced nausea and;or vomiting. Nausea is sometimes listed as a side effect for those taking high dosages of 5-HTP. I did have some mild stomach queasiness when first taking 5-HTP, but it went away.

I commend you for trying "to understand the interaction of the medicines in all common cures for this disease." On 5-HTP, you might want to take a look at the generally favorable report it gets in this posting from the Blue Shield of California:

John Schappi said...

P.S. The California Blue Shield posting does a good job of refuting the warnings you see on Wikipedia and elsewhere about 5-HTP and contamination that are based on a small and flawed study. It concludes:
"there is no firm evidence that this substance has caused or contributed to any toxicity or disease." I made the same point in an earlier posting based on my own research.