Researchers measured the electrical activity of the volunteers' hearts by electrocardiogram, which records the way a heart is beating.
"Particularly those that have a genetic heart condition that predisposes them to abnormal heart rhythms and those with hypertension or high blood pressure should definitely be cautious", Shah said. All measurements were taken at the study's start and every 30 minutes for four hours after consumption. It can increase the total caffeine content in energy drinks as it already contains the stimulant.
Caffeine at doses under 400mg is not expected to induce any electrocardiographic changes, the study authors claimed.
Other common ingredients in the energy drinks analysed in this study included taurine, glucuronolactone and B-vitamins. On the other hand, the placebo drink consists of lime juice, carbonated water, and cherry flavouring.
They saw effects in just three to four hours, suggesting some people should be cautious when consuming energy drinks.More news: Wilder says Fury rematch is 'officially on'
The time it takes for the heart's chambers to contract and then return to a relaxed state is known as a QT interval. An interval too short or too long could result in a life-threatening irregular heartbeat. According to the American Heart Association, the results were concerning: researchers found that participants who drank 32oz of energy drinks in an hour experienced "statistically significant" blood pressure increases and changes in the electrical properties of the heart.
Lead author Dr Sachin A. Sha, of the University of the Pacific in California, said: "We found an association between consuming energy drinks and changes in QT intervals and blood pressure that can not be attributed to caffeine".
"Consumer products and supplements, unlike drugs, do not get necessarily tested for safety", Thomas J. Long School of Pharmacy and Health Sciences' pharmacy professor and study author, Sachin Shah wrote in an email (source).
Researchers conducted the largest controlled study yet of the effects of energy drinks on the heart and blood pressure in healthy adults.
Between 2007 and 2011, emergency department visits linked to energy drinks doubled, according to the Centers for Disease Control and Prevention.More news: Rocketman star Taron Egerton says Elton John won't stop sending him reviews
She said: 'Energy drinks are readily accessible and commonly consumed by a large number of teens and young adults'.
The Organic Energy Drink market research report analyzes adoption trends, future growth potentials, key drivers, competitive outlook, restraints, opportunities, key challenges, market ecosystem, and revenue chain analysis.
Among the study's limitations, it was created to assess the effects of short-term consumption of an energy drink and does not provide insight into long-term effects nor the effects of routine energy drink consumption. The soft drinks concentrate market is also segmented on the basis of end use applications as food Service, mass merchandise, fountain machine and others (Quick Serving Restaurants (QSR) and private clubs).Among these fountain machines is fastest growing segment as it reduces time for drink preparation and offers ease of operation.
"Energy drinks not only have been shown to raise stress levels, increase heart rate, increase blood pressure, they've also been shown to make the blood a little bit thicker", he added, all of which can pose a health risk. She's a professor of pharmacy at University of the Pacific in Stockton, Calif.More news: Celtic Celtic confirm Neil Lennon as new manager