Glucuronolactone (also known as Glucuronic acid lactone) is a naturally occurring organic metabolite found in the body and is an important structural component of connective tissues. This white solid odorless compound, can also be found as an ingredient in some pre-workout products and energy drinks. Find out why.
Does Glucuronolactone has Ergogenic Benefits?
It is difficult to draw conclusions on ergogenic effects of glucuronolactone as its independent ergogenic effects have not been studied. Besides that there is also a lack of information on the compound, which has led to lots of misinformation about its effectiveness and side effects. Studies evaluating the constituents of energy drinks (which include glucuronolactone) suggest no significant increase in energy [1,2]. However, several studies have noted significant improvements in training volume with combination of caffeine, taurine, and glucuronolactone [3-5]. Any muscular function enhancement from such drinks is probably due to their caffeine content.
When glucuronolactone was orally administered to exercise stressed rats there were no significant effects reported .
Glucuronolactone is Ascorbic Acid (Vitamin C) Precursor
Glucuronolactone is necessary for ascorbic acid biosynthesis in animals that are capable of synthesizing ascorbic acid (Vitamin C) endogenously (in the body). . Evidence for this has been presented in some human and animal studies. When six humans ingested D-glucuronolactone, the L-ascorbic acid in plasma rose markedly . Isherwood and coworkers  also reported that the administration of D-glucuronolactone and L-gulonolactone to rats produced an increase in the urinary excretion of L-ascorbic acid.
Glucuronolactone Safety Concerns
There is a rumour that say that glucuronolactone was banned due to brain tumor-related deaths, which was later proven false . Toxicological studies on the genotoxic, teratogenic or carcinogenic potential of D-glucuronolactone are not available. However, D-glucuronolactone is a normal human metabolite formed from glucose and according to European Food Safety Authority  there are no alerts for mutagenicity or carcinogenicity. The no-observed-adverse-effect level (NOAEL) for glucuronolactone is 1000 mg/kg/day, when calculated for a 60 kg person .
Kim, Woojae. “Debunking the effects of taurine in Red Bull energy drink.” Nutrition Bytes 9.1 (2003).
Mets, Monique AJ, et al. “Positive effects of Red Bull® Energy Drink on driving performance during prolonged driving.” Psychopharmacology 214.3 (2011): 737-745.
Forbes, Scott C., et al. “Effect of Red Bull energy drink on repeated Wingate cycle performance and bench-press muscle endurance.” International journal of sport nutrition and exercise metabolism 17.5 (2007): 433.
Hoffman, Jay R., et al. “Effect of a pre-exercise energy supplement on the acute hormonal response to resistance exercise.” The Journal of Strength & Conditioning Research 22.3 (2008): 874-882.
Ratamess, Nicholas A., et al. “Effects of an amino acid/creatine energy supplement on the acute hormonal response to resistance exercise.” International journal of sport nutrition and exercise metabolism 17.6 (2007): 608-623.
Nagao, Noriki, et al. “The Effect of Orally Administering Glucuronolactone to Exercise Stressed Rats.” Hiro to Kyuyo no Kagaku 14.1 (1999): 47-58.
Smirnoff, Nicholas. “L-ascorbic acid biosynthesis.” Vitamins & Hormones 61 (2001): 241-266.
Baker, Eugene M., et al.. “Effect of D-glucuronic acid and D-glucuronolactone on ascorbic acid levels in blood and urine of man and dog.” The American Journal of Clinical Nutrition 8.3 (1960): 369-373.
- Isherwood, F. A., Chen, Y. T., and Mapson, L. W., Biochem. J., 69,l (1954).
- Barbara Mikkelson “Bull Marketed” Retrieved 2. Nov 2013
- EFSA – “Opinion of the Scientific Committee/Scientific Panel: The use of taurine and D-glucurono-gamma-lactone as constituents of the so-called energy drinks”. European Food Safety Authority. Retrieved 3. Nov 2013.