The impact of bariatric surgery on glutathione synthesis in individuals with severe obesity

Authors: TAN, HONG - Singapore General Hospital; HSU, JEAN - Children'S Nutrition Research Center (CNRC); TAI, E SHYONG - National University Of Singapore; CHACKO, SHAJI - Children'S Nutrition Research Center (CNRC); KOVALIK, JEAN-PAUL - Duke-Nus Medical School; JAHOOR, FAROOK - Children'S Nutrition Research Center (CNRC)

Submitted to: Antioxidants
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/6/2024
Publication Date: 8/9/2024
Citation: Tan, H.C., Hsu, J.W., Tai, E., Chacko, S., Kovalik, J., Jahoor, F. 2024. The impact of bariatric surgery on glutathione synthesis in individuals with severe obesity. Antioxidants. 13(8). Article 967. https://doi.org/10.3390/antiox13080967.
DOI: https://doi.org/10.3390/antiox13080967

Interpretive Summary: Glutathione is a biochemical substance made up of three amino acids that includes glycine. It is found in large amounts inside cells and protects against harmful substances. Glutathione levels in red blood cells are decreased in obesity and a decrease in glutathione availability is linked to health-related issues with heart and metabolism. Low plasma glycine concentration in morbidly obese condition in humans is associated with impaired glycine synthesis and this is improved after bariatric surgery. The objective of the study was to examine the impact of bariatric surgery on glutathione synthesis in humans with obesity. The scientists at CNRC found that glutathione concentration in red blood cells was significantly lower in participants with obesity but glutathione synthesis rates were not significantly different. Further, bariatric surgery did not significantly change glutathione concentrations or synthesis rates. More studies are needed before recommending glycine supplementation to individuals with obesity to increase glutathione availability.

Technical Abstract: Glycine is deficient in individuals with obesity but improves following bariatric surgery. Glycine deficiency could impair glutathione (GSH) synthesis and worsen oxidative stress. We examined the impact of obesity-associated glycine deficiency and bariatric surgery on GSH synthesis. Twenty-one participants with severe obesity and twenty-one healthy weight controls were recruited. [1,2-13C2] glycine was infused to measure the erythrocyte (RBC) GSH synthesis rate. Participants with obesity underwent bariatric surgery, and 19 were restudied six months post-surgery. Compared to healthy weight controls, individuals with obesity had significantly lower concentrations of RBC GSH (2.43 +/- 0.23 vs. 2.63 +/- 0.26 mmol/L, p < 0.01). However, there were no differences in GSH fractional synthesis rate [78.0 (51.4–123.7) vs. 76.9 (49.3–110.1) % pool/day, p = 0.58] or absolute synthesis rate [1.85 (1.25–3.32) vs. 1.92 (1.43–3.03) mmol/L RBC/day, p = 0.97]. Despite a post-surgery increase in glycine concentration, no statistically significant changes in RBC GSH concentration or synthesis rates were detected. Further, the significant correlation between plasma glycine and RBC GSH concentration at baseline (r = 0.46, p < 0.01) was also lost following bariatric surgery. GSH concentration was significantly lower in participants with obesity, but bariatric surgery did not significantly increase GSH concentrations or synthesis rates.