Energy drinks have become increasingly popular in recent years, however a new study has found that they may disturb the heart's natural rhythm and increase blood pressure.

US scientists analysed the results from seven studies to assess the impact these drinks may have on a person's health.

They found that the drinks can prolong the heart's QT interval. This is a segment of the heart's rhythm that is measured on an ECG (electrocardiogram). A prolonged QT interval can cause serious irregular heartbeats and in some cases, sudden cardiac death.

The scientists found that among almost 100 people who had consumed between one and three cans of energy drinks, their QT interval was 10 milliseconds longer than people who had not consumed these drinks.

"Doctors are generally concerned if patients experience an additional 30 milliseconds in their QT interval from baseline. QT prolongation is associated with life-threatening arrhythmias (irregular heartbeat). The finding that energy drinks could prolong the QT, in light of the reports of sudden cardiac death, warrants further investigation," they commented.

Meanwhile, the analysis also revealed that systolic blood pressure - that is the number on top in a blood pressure reading, rose by an average of 3.5 points among over 130 people who consumed energy drinks.

"The correlation between energy drinks and increased systolic blood pressure is convincing and concerning, and more studies are needed to assess the impact on the heart rhythm. Patients with high blood pressures or long QT syndrome should use caution and judgment before consuming an energy drink," the scientists insisted.

They added that since energy drinks also contain caffeine, people who do not normally consume a lot of caffeine ‘might have an exaggerated increase in blood pressure'.

Older people and anyone with health problems may also suffer ‘more heart-related side-effects' from these drinks, the team said.

They presented their findings at the American Heart Association's Epidemiology and Prevention/Nutrition, Physical Activity and Metabolism 2013 Scientific Sessions.