Each and every energy drink contains its own special formula, but it’s unclear how these recipes combine to “give you wings” and make you feel so wired. Weirdly, their results leave us with more questions than answers.
Sure, energy drinks contain a lot of caffeine, which definitely contributes to that wired feeling. But as the authors of this study, published February 26 in the Journal of Nutrition, point out, energy drinks actually contain a host of other ingredients like taurine and glucuronolactone. This trial demonstrated that it’s nearly impossible to pin the effects of an energy drink on just one ingredient. Instead, they suggest that there may be a more complex interaction among ingredients that’s really behind how energy drinks make you feel.
To get to the bottom of how energy drinks make us feel, the researchers behind the study, led by Dr. Stephan Bischoff, a professor of Nutritional Medicine at the University of Honheim, gave volunteers a combination of store-bought and lab-made energy drinks.
Thirty-eight individuals consumed either a traditional energy drink, a control drink with no additives, one of several mixtures that contained each individual ingredient, or a mixture of just two of those ingredients combined. Within just an hour of drinking the store-bought energy drinks, (in this case Red Bull), 11 percent of his participants reported symptoms like tremors, increased heart rate, and, in one case, nausea. The volunteers also exhibited significant increases in blood pressure and insulin sensitivity — both of which could be risky for people who either have previous heart conditions or diabetes.
Participants also showed changes in their Q-T intervals — a measurement of how long it takes the heart to contract and then refill again with blood. That interval is sometimes used to asses whether a substance could cause heart arrhythmias in certain “toxic” doses. After drinking the energy drinks, the authors noted that participants had sightly longer Q-T intervals than expected. These changes in Q-T interval were statistically significant, but the researchers note that they probably weren’t large enough to raise concerns for most people.
“The adverse effects were marginal and possibly too small for short-term clinical consequences, at least in healthy individuals,” the authors write.
What really perplexed the authors was that they couldn’t figure out which ingredients in the energy drinks were actually causing these effects. When they administered control drinks with only taurine, glucuronolactone, or caffeine, they didn’t see the same changes. For instance, caffeine elevated heart rate but didn’t have the same effects on Q-T interval. When they combined taurine and caffeine together, they noticed slight increases in heart rate, and oddly, a reduction in the Q-T interval, but the changes weren’t statistically significant.
This combination seems to suggest that the ingredients in energy drinks interact with one another to create effects that are greater than the sum of their parts, a type of synergy called an “additive reaction.” Previous research has shown that taurine has a negative “additive reaction” when it’s mixed with alcohol, but it doesn’t seem to have large effects on energy on its own.
The question is whether mixing it with caffeine creates a special boost. These researchers suggest it might — though their study wasn’t enough to prove it.
“An additive effect of taurine and caffeine leading to a reduction of HR and QTc interval could be hypothesized,” they write. “However, in our study, increased HR and a prolonged QTc interval were observed after energy drink consumption. So far, these effects caused by energy drinks cannot be explained by any of the tested components: caffeine, taurine, or glucuronolactone.”
So as inconclusive as it may be, this research does make a statement with its negative results. When it comes to figuring out why energy drinks give us wings — or cause a battery of health effects — there’s no single chemical that’s responsible.
Instead, we’re dealing with the combined effects of a unique formulation that, for now, seems to be greater than the sum of its parts.
Background: Case reports suggest a link between energy drinks (EDs) and adverse events, including deaths. Objectives: We examined cardiovascular and metabolic effects of EDs and mixtures providing relevant ingredients of EDs compared to a similarly composed control product (CP) without these components.
Methods: This randomized, crossover trial comprised 38 adults (19 women, mean BMI 23 kg/m2, mean age 22 y). We examined effects of a single administration of a commercial ED, the CP, and the CP supplemented with major ED-ingredients at the same concentrations as in the ED. The study products were administered at 2 volumes, 750 or 1000 mL.
Results: Both volumes of the study products were acceptably tolerated with no dose-dependent effects on blood pressure (BP, primary outcome), heart rate, heart rate corrected duration of QT-segment in electrocardiography (QTc interval), and glucose metabolism. After ED consumption, 11% of the participants reported symptoms, in contrast to 0–3% caused by other study products. After 1 h, administration of an ED caused an increase in systolic BP (116.9 ± 10.4 to 120.7 ± 10.7 mmHg, mean ± SD, P < 0.01) and a QTc prolongation (393.3 ± 20.6 to 400.8 ± 24.1 ms, P < 0.01). Also caffeine, but not taurine or glucuronolactone, caused an increase in BP, but no QTc prolongation. The BP effects were most pronounced after 1 h and returned to normal after a few hours. All study products caused a decrease in serum glucose and an increase in insulin concentrations after 1 h compared to baseline values, corresponding to an elevation in the HOMA-IR (ED + 4.0, other products + 1.0–2.8, all P < 0.001).
Conclusion: A single high-volume intake of ED caused adverse changes in BP, QTc, and insulin sensitivity in young, healthy individuals. These effects of EDs cannot be easily attributed to the single components caffeine, taurine, or glucuronolactone. This trial was registered at clinicaltrials.gov as NCT01421979.