Saturday Nov 9, 2013 (foodconsumer.org) -- Taking glycine and cysteine as dietary supplements can help restore glutathione in cells of people with glutathione deficiency, according to a study recently published in the Journal of Clinical Endocrinology & Metabolism.

Glutathione considered one of the most important antioxidants in human body plays a very crucial role in all sorts of physiological functionalities in cells.  One major role it plays as an antioxidant is preventing cellular components from being damaged by reactive oxygen species such as free radicals and peroxides generated from metabolism of sugars and fatty acids.  These reactive components are otherwise causes for many chronic diseases if not taken care of properly.

The current study led by Rajagopal V. Sekhar, M.D. from Baylor College of Medicine in Houston, TX  and colleagues shows that HIV patients with glutathione deficiency had glutathione levels restored or improved after 14 days of oral supplementation with cysteine and glycine.  

Early studies have found supplementation with glutathione, which is an expensive dietary supplement, in a dose of 3 grams per day cannot help overcome glutathione deficiency effectively.  Glutathione is a tripeptide consisting of cysteine, glutamic acid and glycine.  From a chemical viewpoint, it is possible that taking glutathione precursors cysteine and glycine may help biosynthesis of glutathione.

It have been reported that HIV infected patients may have impaired oxidation of fatty acids indicating a mitochondrial defect, according to the study report.  Mitochondria are the place where fuel is used to produce energy.

For the study, eight older glutathione deficient HIV infected men were assigned to take cysteine and glycine orally as dietary supplements and the researchers measured "glutathione synthesis, fasted and insulin-stimulated (fed) mitochondrial fuel oxidation, insulin sensitivity, body composition, anthropometry, forearm-muscle strength and lipid profiles" after supplementation.

Supplementation with cysteine and glycine restored the impaired synthesis which was found to contribute to glutathione deficiency.  This improvement was coupled with marked improvement in fasted and fed mitochondrial fuel oxidation, the authors reported.  Other improvements were observed in "insulin sensitivity, body composition, anthropometry, muscle strength and dyslipidemia."

The study concluded that taking cysteine and glycine dietary supplements can not only restore the glutathione reservoir in people with glutathione deficiency, but also improve  mitochondrial fat and carbohydrate oxidation in both fasted and fed states and insulin sensitivity, body composition and muscle strength.

Both cysteine and glycine are amino acids.  The former, which is critical for glutathione biosynthesis, is not as abundant as other amino acids.  Dietary supplements of this amino acid may be a good source.  Cysteine is a food ingredient commonly used in the bakery industry as a dough conditioner.  Glycine is relatively cheaper.  It can help not only biosynthesis of glutathione, but also prevent the damaging glycation induced by reactive sugars and their metabolic intermediates. (David Liu, PHD)