(HealthDay News) — Some energy drinks appear to significantly improve endothelial function, while other energy drinks and coffee do not, according to a study published in the November 1 issue of The American Journal of Cardiology.

Janos Molnar, MD, and John C. Somberg, MD, both from the American Institute of Therapeutics in Lake Bluff, Illinois, evaluated the effect of three energy drinks and coffee on endothelial function with a device that uses digital peripheral arterial tonometry to measure the reactive hyperemia index (RHI). Six healthy volunteers received energy drinks in a random order at least two days apart. Drinks studied were 250ml Red Bull (80mg caffeine), 57ml 5-hour Energy (230mg caffeine), and 355ml NOS (120mg caffeine). Sixteen volunteers received a cup of 473ml coffee containing 240mg caffeine. Evaluations occurred before drink (baseline) and at 1.5 and four hours after drink.

The researchers found that Red Bull and 5-hour Energy significantly improved endothelial function at four hours after drink, whereas NOS and coffee did not change endothelial function significantly.

“Caffeine does not appear to be the component responsible for these differences,” conclude the authors.

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