A look at what's behind the hype and health concerns

By Allison Lawlor

It’s a sweltering summer day. You’ve just run five kilometres along a hilly trail, and the sweat is pouring off you. You’re thirsty and looking for a boost, so you reach for one of the countless energy drinks on store shelves promising increased endurance and mental clarity in a bottle.

Think again, says Judy Fraser Arsenault, a dietitian in the Department of Applied Human Nutrition at Mount Saint Vincent University in Halifax, NS. Any zip you get from these beverages is mainly from large amounts of caffeine in them. "Caffeine is a known stimulant that generally increases alertness and reduces fatigue," says Fraser Arsenault. "Energy drinks aren't really a healthy choice for quenching your thirst."

Health concerns
Marketing claims of drinks, such as Red Bull® Energy Drink and SoBe Adrenaline Rush™, are often hyped, suggests Fraser Arsenault, and could be misleading. There have been reports of adverse reactions, including vomiting and heart irregularities, which occurred when people drank too much or mixed the energy drinks with alcohol. That’s why Health Canada has advised consumers to drink no more than 500 ml or two cans a day of Red Bull® Energy Drink. – Classified as a natural health product, it's the only energy drink Health Canada has evaluated so far, but it would be prudent to approach other similar beverages with the same precaution.

Energy vs. sports drink
"Energy drinks shouldn’t be confused with sports drinks," says Fraser Arsenault. Sports drinks such as Gatorade® or POWERade® are formulated to help re-hydrate the body. Geared toward athletes wanting to replenish their bodies with energy and electrolytes after serious physical activity, they are popular among average consumers.

What's in them?

Sports drinks usually contain:
•    sugars (such as sucrose and glucose)
•    electrolytes (sodium, potassium, and chloride) -- electrolytes maintain salt and potassium balances in the body

Energy drinks usually contain:
•    a stimulant, such as caffeine
•    glucuronolactone (a carbohydrate)
•    taurine (an amino acid and one of the building blocks of protein)
•    herbs, such as guarana and ginseng
•    sugar, sometimes

Some energy drinks also contain B-complex vitamins, involved in energy metabolism, adds Fraser Arsenault. High doses of vitamins can be harmful, though, and it takes time for the body to absorb the vitamins, she cautions, so it "isn’t going to suddenly give you an energy boost."

The makers of Impulse™ Energy Drink would disagree. They claim that its combination of vitamins, caffeine and carbohydrates not only increases physical and mental alertness but also improves reaction time, stamina, metabolism, and reduces the body’s stress recovery period.

The problem, says Fraser Arsenault, is not enough scientific data to back the health claims of some ingredients, or to advise what quantities are safe for human consumption. For example, while taurine is a naturally occurring amino acid, not enough is known about its safety in large doses, she says. Some energy drinks contain one gram of taurine per 246 ml can.

Caffeine high
Caffeine content is also not always accurately listed on the labels, she says. For example, yerba mate and guarana, two herbal plant extracts that can be found in energy drinks, both contain caffeine. But because they're considered natural products they don’t have to be listed as caffeine sources.

The listed caffeine content is usually high: SoBe Adrenaline Rush™, for example, lists 79 mg of caffeine per 246 ml can. By comparison, one 8 oz. (227 ml) cup of brewed coffee has about 135 mg of caffeine. The trouble with too much caffeine depends how sensitive you are to its effects. It can cause insomnia, headaches, irritability, and nervousness in some people.