Energy drinks, once aimed exclusively at athletes, have become a significant force in the worldwide beverage market. They come in a dizzying variety of colors, often feature exotic ingredients — guarana, ginseng, and ginkgo biloba, to name just a few — and aren’t shy when it comes to health claims. Marketers’ efforts to rebrand such drinks as “nutrition beverages” have continued to spur sales growth, though this comes at a time when the content of the drinks is coming under increased scrutiny.

A 2010 review of relevant nutritional studies by the Mayo Clinic, “Energy Beverages: Content and Safety,” aimed to look broadly at the contents of sports drinks, high-energy beverages and liquid supplements, and to explore the health impacts of such beverages.

The review’s findings include:

• Among the 23 separate ingredients contained in four popular energy beverages, the most common ingredient in energy beverages was caffeine (up to five times as much as an 8-oz cup of instant coffee).
• Studies linked oral caffeine intake with immediate rises in blood pressure, stiffening of arteries and faster and harder heartbeats.
• One of the studies reviewed had subjects drink two energy drink cans per day for a week. The study found subjects’ heart rates increased between 5 and 7 beats per minute, and systolic blood pressure increased by 10 mm, suggesting increased risks to people suffering hypertension in drinking energy beverages.
• Studies were generally split over the question of performance enhancement from high-caffeine energy drinks. Among physically active university students, no improvement was noted throughout the trials, but in a different study of 12 professional cyclists, a significant improvement in time trials was noted.

The authors state that, overall, the benefits of such drinks on exercise outcomes are at least questionable and there exists negative short-term health impacts in consuming highly caffeinated energy beverages.

Tags: consumer affairs, exercise, nutrition, safety