Nothing to do with energy: energy drinks can kill your muscles

The global market for energy drinks was estimated at USD 46 billion in 2020. According to the latest projections, this is expected to reach USD 108 billion by 2031. This would correspond to an annual growth rate of around 8% [1].

Also due to aggressive marketing strategies by manufacturers, men between the ages of 18 and 34 drink the most energy drinks in the USA, while almost a third of teenagers between the ages of 12 and 17 also drink these drinks regularly [2].

The ingredients

The most common ingredients in most energy drinks are caffeine (between 70 - 240 mg depending on the drink), guarana, sugar, taurine, glucuronolactone, ginseng and B vitamins. However, certain ingredients in these drinks can have serious health effects on the cardiovascular system, our brain, gastrointestinal tract and metabolism. Due to the usually low pH value, these drinks are also highly corrosive to teeth.

Between 2007 and 2011 alone, the number of visits to an emergency room in the USA due to the consumption of energy drinks doubled. One tenth of visits resulted in hospitalisation [2]. Excessive caffeine consumption can lead to restlessness, insomnia, gastrointestinal disorders and anxiety [3].

Taurine is a chemical compound commonly found in animals, including humans, that is associated with numerous positive functions in the human body. For example, taurine appears to promote cognitive functions [4], as well as regulate the contractile function of muscles [5]. Furthermore, a few weeks ago a research article appeared in Science about the fact that a lack of taurine can promote the ageing process and that supplementation of taurine in mice increases the health span [6]. Taurine has also been linked to attenuating oxidative damage in muscles after intense exercise [7].

Up to this point, this reads rather positively. But now comes the other side of the coin.

Glucuronolactone is a carbohydrate and is often used in conjunction with caffeine or taurine in energy drinks. The influence of glucuronolactone and/or the interaction between glucuronolactone and taurine or caffeine has been little researched. However, there is evidence that these food additives or their interaction lead to neurotoxic effects in mice [8].

Excessive consumption of sugar through energy drinks has various negative consequences for the body. In the context of energy drinks, it is associated with cardiac arrhythmia, blood pressure problems and obesity [9-11].
To summarise, energy drinks can therefore be associated with various negative consequences for our health. The impact on the health of consumers and athletes is still largely unknown.

First study investigates the influence of energy drinks on muscle cell formation in vitro

A research team has investigated the impact of energy drinks on muscle cells in mice [12]. To do this, they exposed muscle cells from mice to different energy drinks and different concentrations in order to investigate the effects on skeletal muscle. The researchers analysed eight energy drinks from four well-known manufacturers: Red Bull, Red Bull Zero, Monster Energy, Monster Ultra Paradise, Rockstar, Rockstar Sugar Free, Celsius Live Fit and Celcius Heat. To ensure that cell growth and differentiation are not negatively affected by the low pH value of the energy drinks, they raised it to a pH value of around 7 using sodium hydroxide.

First, the researchers investigated the influence of different concentrations of RedBull on cell toxicity. The dilutions used were: 1:100, 1:50, 1:20, 1:15, 1:10, 1:8, 1:5, 1:2 and 1:1. Most dilutions had no major effect on the muscle cells with the exception of the 1:2 and 1:1 dilutions, which killed 30 - 40% of the muscle cells.

All eight energy drinks were then added to muscle cells on different culture media at 1:50 and 1:5 dilutions. In the culture medium, which promotes the growth of muscle cells, no increased toxicity was detectable with almost all dilutions and energy drinks. With two exceptions: Celcius Live Fit and Celsius Heat elicited 14 and 28% cell death, respectively, at the 1:5 dilution. On average, the other energy drinks had a caffeine concentration of 32.5 mg/100 ml. Celcius Live Fit and Celsius Heat have a caffeine concentration almost twice as high at 56.3 and 63.4 mg/100 ml respectively. This could be one reason for the higher cell toxicity. A future study that doubles the caffeine concentration in the other energy drinks could shed light on this.

In the culture medium, which promotes the differentiation of muscle cells, the 1:5 dilutions of almost all energy drinks showed toxic effects of around 20 - 30% on the muscle cells. The exception here was Red Bull Zero, which had no effect on cell death at either dilution.

In the next step, the research group investigated the influence of energy drinks on muscle cell differentiation. The differentiation of muscle cells is the process by which undifferentiated cells develop into specialised muscle cells. This process is regulated by various factors, including gene expression, signalling pathways and environmental influences. Muscle cells that were not exposed to an energy drink served as a negative control.

Exposure of muscle cells to energy drinks had a drastic effect on myoblast fusion. Myoblast fusion in muscle development causes the formation of multinucleated myotubes, the building blocks of skeletal muscle fibres. Six out of eight energy drinks inhibited the formation of these myotubes at a dilution of 1:5, the only exceptions being Red Bull and again Red Bull Zero. An indication of the lower inhibition in Red Bull and Red Bull Zero could be the vitamin B6 concentration, which is 2 to 4 times higher compared to the other energy drinks. Several studies show a positive effect of vitamin B6 on the development and differentiation of muscle cells [13,14].

Conclusion

As interesting as the study may be, it is also limited. It does not provide any answers to the effects of the individual ingredients or their biochemical interaction on the muscle cells. Mechanistic insights are not possible as the energy drinks were analysed as a whole with their different formulations. The identification of key molecules responsible for toxicity and the inhibition of cell growth and/or differentiation requires further studies looking at the individual ingredients in isolation and in combination. Nevertheless, it is the first study to observe negative effects of energy drinks on muscle cell formation in vitro.

References:

1. Energy Drinks Market Size, Share & Growth | Industry Report, 2031. [cited 21 Jun 2023]. Available: https://www.alliedmarketresearch.com/energy-drink-market
2. Rockville P. Energy Drinks | NCCIH. In: Nccih [Internet]. 2018 [cited 21 Jun 2023]. Available: https://www.nccih.nih.gov/health/energy-drinks
3. Jee HJ, Lee SG, Bormate KJ, Jung YS. Effect of Caffeine Consumption on the Risk for Neurological and Psychiatric Disorders: Sex Differences in Human. Nutr 2020, Vol 12, Page 3080. 2020;12: 3080. doi:10.3390/NU12103080
4. Jia N, Sun Q, Su Q, Dang S, Chen G. Taurine promotes cognitive function in prenatally stressed juvenile rats via activating the Akt-CREB-PGC1α pathway. Redox Biol. 2016;10: 179-190. doi:10.1016/J.REDOX.2016.10.004
5. Higgins JP, Tuttle TD, Higgins CL. Energy Beverages: Content and Safety. Mayo Clin Proc. 2010;85: 1033-1041. doi:10.4065/MCP.2010.0381
6. Singh P, Gollapalli K, Mangiola S, Schranner D, Yusuf MA, Chamoli M, et al. Taurine deficiency as a driver of aging. Science. 2023;380: eabn9257. doi:10.1126/SCIENCE.ABN9257/SUPPL_FILE/SCIENCE.ABN9257_MDAR_REPRODUCIBILITY_CHECKLIST.PDF
7. Thirupathi A, Pinho RA, Baker JS, István B, Gu Y. Taurine Reverses Oxidative Damages and Restores the Muscle Function in Overuse of Exercised Muscle. Front Physiol. 2020;11: 582449. doi:10.3389/FPHYS.2020.582449/BIBTEX
8. Boyina R, Dodoala S. Evaluation of the neurobehavioural toxic effects of taurine, glucuronolactone, and gluconolactone used in energy drinks in young rats. Turkish J Pharm Sci. 2020;17: 659-666. doi:10.4274/tjps.galenos.2019.33602
9. Voskoboinik A, Koh Y, Kistler PM. Cardiovascular effects of caffeinated beverages. Trends Cardiovasc Med. 2019;29: 345-350. doi:10.1016/J.TCM.2018.09.019
10. Mansour B, Amarah W, Nasralla E, Elias N. Energy drinks in children and adolescents: demographic data and immediate effects. Eur J Pediatr. 2019;178: 649-656. doi:10.1007/S00431-019-03342-7/FIGURES/2
11. Clapp O, Morgan MZ, Fairchild RM. The top five selling UK energy drinks: implications for dental and general health. Br Dent J 2019 2267. 2019;226: 493-497. doi:10.1038/s41415-019-0114-0
12. Park SY, Karantenislis G, Rosen HT, Sun H. Effects of energy drinks on myogenic differentiation of murine C2C12 myoblasts. Sci Reports 2023 131. 2023;13: 1-14. doi:10.1038/s41598-023-35338-7
13. Kumar A, Kumar Y, Sevak JK, Kumar S, Kumar N, Gopinath SD. Metabolomic analysis of primary human skeletal muscle cells during myogenic progression. Sci Reports 2020 101. 2020;10: 1-14. doi:10.1038/s41598-020-68796-4
14. Komaru T, Yanaka N, Kumrungsee T. Satellite cells exhibit decreased numbers and impaired functions on single myofibers isolated from vitamin B6-deficient mice. Nutrients. 2021;13: 4531. doi:10.3390/NU13124531/S1