The cardiac death of a 14-year-old American girl in 2015 made headlines around the world. Caffeine-related cardiac arrhythmias caused by energy drinks that the girl had drunk the day before are said to have been to blame for the tragedy. The 14-year-old had suffered from Ehlers Danlos Syndrome, a rare disease that can affect the heart.
A study from 2013, however, shakes the apparent harmlessness of energy drinks. According to her, the caffeinated fashion drinks can change the heartbeat. For example, one hour after consuming an energy drink with caffeine and taurine, researchers found in 18 test persons that the contractions of the heart had become stronger. However, this effect of caffeine has long been known. However, it remains unclear whether the changed heartbeat has negative effects on health. In addition, the scientists withhold more detailed information. There is only a brief summary of their study, so some skepticism is warranted.
Adverse effects hardly studied
This is a general problem when assessing the safety of such beverages – meaningful studies have not yet been carried out. A summary of previous study results provides a contradicting picture, but few concrete findings. Energy drinks, for example, could potentially increase heart rate and blood pressure in the short term, but this is not the case in all studies. In general, most examinations checked the heart rate, blood pressure and certain blood values no more than three hours after consuming a single energy drink.
Only one team of scientists researched the effects over a longer period of time: 38 men were examined who drank energy drinks for ten weeks every day before exercising. But even ten weeks is too short to assess long-term effects on heart health. In addition, the number of 38 participants is too small to get meaningful results.
Conclusions from case reports difficult
What remains in addition to studies are case reports such as that of the deceased 14-year-old American. Such case reports up to 2008 have been compiled by the German Federal Institute for Risk Assessment (BfR) or a US research group led by Kevin Clauson. The German BfR reports the results of a Swedish investigation of hospital records. In three cases, young people who had previously consumed energy drinks, sometimes in combination with alcohol, died suddenly. However, it is not certain that the energy drinks caused death.
The BfR also reports cases of acute kidney failure or epileptic seizures – possibly triggered by taurine in energy drinks. Clauson lists four cases in which patients had epileptic seizures after consuming several energy drinks without consuming alcohol at the same time. However, it is by no means possible to conclude from these case reports whether the energy drinks were actually to blame for the seizures, and how great the risk for them would be in the general population.
Between 2001 and 2007 six German poison information centers documented around 90 cases of undesirable effects after consuming energy drinks. The symptoms ranged from abdominal pain, high blood pressure, increased heartbeat, ventricular fibrillation, visual disturbances to seizures. However, it is unclear whether those affected had not also consumed other medications, drugs or alcohol. Here, too, the following applies: whether and to what extent energy drinks are involved in the poisoning cases cannot be said without any doubt.
Children and teenagers should be careful
According to a recent Europe-wide survey, the majority of young people between the ages of ten and 18 (86 out of 100 respondents) consume energy drinks. Even younger people are enthusiastic about the caffeinated sugar drinks. About every fifth child between the ages of three and ten consumes such drinks.
For most adults, up to 400 milligrams (mg) of caffeine per day seems safe. Depending on the strength, this corresponds to around two to four cups of coffee. Energy drinks approved in the EU may contain a maximum of 80 milligrams of caffeine per quarter of a liter. For adolescents and children, however, experts do not know how large the still safe daily dose is – however, it is very likely to be significantly lower.
Caffeine is only safe in moderation
Those who drink coffee in moderation do not seem to harm their heart. There is no evidence that moderate doses of caffeine can induce arrhythmias or atrial fibrillation. Even moderate, regular caffeine consumption does not appear to increase blood pressure in the long term, or at most slightly. However, this should not increase the risk of dying from heart disease.
However, large amounts of caffeine can very well have health consequences. Larger doses of energy drinks can trigger palpitations, tremors, excitement and digestive problems. Especially in people with heart disease, larger doses of caffeine could cause cardiac arrhythmias or other heart problems. In epilepsy patients, caffeine could also cause epileptic seizures.
Interaction with other ingredients unknown
In addition to caffeine and sugar, many energy drinks contain other ingredients with allegedly invigorating effects, including taurine and glucuronolactone. The extent to which these substances could enhance the effects of caffeine or undesirable side effects has not been adequately researched.
Taurine is an important basic substance for many metabolic processes, which the body can normally produce itself. Both taurine and glucuronolactone occur naturally in foods, but in far lower concentrations. In an assessment from 2009, the European Food Authority EFSA assumes the harmlessness of taurine and glucuronolactone as additives in energy drinks. However, this assessment is based on toxicity studies on rats and mice. A safety assessment of energy drinks overall by this authority is still pending.
The above-mentioned Europe-wide survey on consumer behavior shows that more than half of adults and adolescents consume energy drinks together with alcohol. Interactions between alcohol and caffeine or other energy drink ingredients have also been insufficiently researched.
In any case, the German Federal Institute for Risk Assessment advises caution until further test results on humans are available.