The use of taurine and D-glucurono-γ-lactone as constituents of the so-called “energy” drinks

Taurine. Upon oral exposure taurine is readily bioavailable in the systemic circulation. The Panel concludes that new ADME data support the contention that oral exposure to taurine was not The use of taurine and D-glucurono-γ-lactone as constituents of the so-called “energy” drinks increasing taurine levels in the brain, because in rat studies, brain taurine levels did not increase after dosage. The SCF already concluded in 1999 that toxicological studies did not reveal any indication for a genotoxic, teratogenic or carcinogenic potential of taurine. It can be concluded that the NOAEL derived from a new 13-week oral neurotoxicity study in male and female rats including functional observational battery and locomotor activity tests, confirmed the NOAEL established in the prior 13-week study, described already by the SCF in 2003, of 1000 mg taurine/kg bw/day, and provided evidence for a NOAEL of 1500 mg taurine/kg bw/day for behavioural effects. The results of this study were sufficient to address the concerns raised previously, notably the observation of increased activity and possible decrements in motor skills on the rotarod. The NOAEL of at least 1000 mg/kg bw/day for pathological changes is respectively 120-fold higher than the estimated mean and 43-fold higher than the estimated 95th percentile exposure to taurine from “energy” drinks only, when calculated for a 60 kg person. Given that taurine is a natural body constituent, the Panel concludes that these margins of safety are sufficiently large to conclude that exposure to taurine at the levels mentioned above is not of safety concern. D-glucurono- γ-lactone. Toxicological studies on the genotoxic, teratogenic or carcinogenic potential of D-glucurono-γ-lactone were not available. However, D-glucurono-γ-lactone is a normal human metabolite formed from glucose and there are no structural alerts for mutagenicity or carcinogenicity. At physiological pH it is in equilibrium with glucoronic acid, its immediate precursor. Dglucurono-γ-lactone and its hydrolysis product glucuronic acid are endogenous metabolites in humans and other mammals, they occur naturally in several dietary sources and are readily metabolized to innocuous products and excreted. Furthermore, in the high dose 13-week rat studies there was no evidence of any effect on the gonads which might indicate the need for The use of taurine and D-glucurono-γ-lactone as constituents of the so-called “energy” drinks The NOAEL for D-glucurono-γ-lactone of 1000 mg/kg bw/day is 200-fold higher than the estimated mean and 71-fold higher than the estimated 95th percentile exposure to Dglucurono- γ-lactone from “energy” drinks only, when calculated for a 60 kg person. Given the fact that D-glucurono-γ-lactone is a natural body constituent the Panel concludes that these margins of safety are sufficiently large to conclude that exposure to D-glucurono-γ-lactone at the levels mentioned above is not of safety concern. Overall, the Panel concludes that the exposure to taurine and D-glucurono-γ-lactone at the levels currently used in “energy” drinks and mentioned in the present opinion is not of safety concern. The ANS Panel agrees with the considerations of the SCF Opinion from 2003 on the fact that it is unlikely that D-glucurono-γ-lactone would have any interaction with caffeine, taurine, alcohol or the effects of exercise. The Panel also concludes, based on the new data available, that additive interactions between taurine and caffeine on diuretic effects are unlikely. Other interactions between taurine and caffeine were not investigated.