Recently, JP Richie Jr. published an article where oral glutathione ingestion was shown to be successful in raising body stores of glutathione (PMID 24791752) http://www.ncbi.nlm.nih.gov/pubmed/?term=24791752
It has been my understanding that oral glutathione has been demonstrated to be relatively inneffective in human subjects. This paper claims a 30-35% increase in glutathione levels were found in healthy adults. This flies in the face of decades of previous research. Comments would be appreciated.
Dr. Gutman: As you have said, oral gluathione availability in human subjects is very limited.
We know that limited studies in humans have reported insignificant absorption of GSH. Human gastrointestinal tract and liver contain significant levels of the enzyme, gamma-glutamyltransferase, which recycles GSH precursors; consequently the absorption of GSH is very limited. This is the reason that N-acetyl-L-cysteine has been considered for diabetics.
Here is a study that may guide you in 'a direction'. http://www.ncbi.nlm.nih.gov/pubmed/11029607, I am not sure what your application is, but in general oral glutathione intake that has not been altered to increase bioavailability is an expensive and somewhat ineffective way to increse levels in the body. Taking NAC is more productive and effective, and may be more effective if taking with Glutamine and Glycine. .
It is well known that N-acetyl-L-cysteine is more absorbed and bioavailable than GSH is. It comes from the amino acid, L-cysteine; L-cysteine is a precursor of GSH (along with the amino acids, L-glutamine and glycine). Glutathione (GSH) is L-γ-glutamyl-L-cysteinyl-glycine.
The current question is different; Dr Jimmy Gutman’s question is clear cut and well-articulated. He states in his question that JP Richie Jr. recently published an article where oral glutathione ingestion was shown to be successful in raising body stores of glutathione. This is in stark contrast to what is known - that oral glutathione is relatively ineffective in human subjects. Dr Gutman is wondering whether this observation by JP Richie Jr can be explained.
Dr. Kandaswami is quite correct in his analysis of my question. I will likely try to contact Dr. Richie to get his personal viewpoint on why this one study has shown different results from historical exeperience/
i had the same question and asked it of product developers in several companies and am still awaiting replies. my best guess is the liposomal system increases the percent absorption
In a randomized, double-blind, placebo-controlled clinical trial in 2011, conducted at Bastyr University Research Institute, Kenmore, WA and the Bastyr Center for Natural Health, Seattle, WA, reported that short-term, oral intake (500 mg twice daily administered to volunteers for 4 weeks) GSH does not improve glutathione status or reduce markers of oxidative stress in healthy adults. The authors indicated that routine supplementation might not offer health benefits in the absence of disease or oxidative challenge.
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3162377/
A more recent set of work is using S-acetyl glutathione, better than N-acetyl-cysteine
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