Caffeine-laden energy drinks are popular, but they can make blood vessels less efficient, suggests a small study.
These beverages, sold as Monster and Red Bull, to name two people, were linked to cardiac, nervous and stomach problems, say the researchers.
"Many young people use energy drinks when they are exercising, a time when they need their artery function to be in their upper part," said lead researcher Dr John Higgins. He is a professor of medicine at McGovern Medical School at the University of Texas Health Science Center in Houston.
Exercise and sports require maximum blood flow so that oxygen can quickly reach the cells, Higgins said. Energy drinks that reduce the diameter of the vessels, in effect, restrict blood flow and oxygen delivery, he explained.
"It is more work for the heart and less oxygen supply to the heart. This could explain why there were cases in which children had cardiac arrest after an energy drink," he said.
In addition, people often drink energy drinks so that they get the full effect on a shot and this can be dangerous, said Higgins.
"These drinks are not intended for children," warns Higgins. In addition, people younger than 18, women who are pregnant or who are breastfeeding, caffeine-sensitive individuals, those who take stimulants or caffeine-based drugs or those with heart disease should stay away from energy drinks, he added.
There is no proven benefit
The study included 44 healthy and non-smoker medical students in their 20 years. The researchers examined the effect of an energy drink of 710ml in cells that had blood vessels, called endothelial cells.
The function of these cells was tested before and after the participants consumed the energy drink and 90 minutes later. The researchers observed dilatation mediated by arterial flow: an ultrasound measurement that is an indicator of the health of the blood vessels.
After 90 minutes, the internal diameter of the blood vessels tested was sharply lower, on average, than before, the researchers found.
This negative effect on blood vessels may be related to the ingredients in the energy drink, such as caffeine, taurine, sugar and other herbs, the researchers suggested. Taurine is an amino acid that is promoted as an energy boost and originally extracted from bull sperm, hence the name of Red Bull, said the researchers.
According to Dr. David Katz, director of the Yale-Griffin Prevention Research Center at Yale University, "the endothelial function is, in general, a powerful cardiovascular risk indicator."
But, said Katz, "this is a small study that only looks for acute effects and can not be considered proof that energy drinks damage the cardiovascular system over time."
Having said that, the combination of sugar and stimulants in these drinks has no proven benefits, added Katz.
"There are better ways to boost energy, such as standing and having a bit of exercise," he suggested. "In the absence of a reliable benefit, even a low level of risk is obligatory."
"Drinks are safe & # 39;
A spokesman for a pressure group representing many energy drink makers said that drinks are safe.
"The energy drinks of the mainstream contain about half of the caffeine of a cup of caffeine of similar size, and have been widely studied and confirmed safely for consumption by government security authorities around the world," said William Dermody, spokesman of the American Beverage Association. "Nothing in this preliminary investigation contrasts this fact well established."
The results of the study are scheduled for presentation on November 12 at a meeting of the American Heart Association in Chicago.
The investigation presented at the meetings is usually considered preliminary until it is published in a peer-reviewed journal.