Fr-chette stresses that supplements come with certain risks. "Their purity and preparation aren't as controlled as prescription medication," he says. "Sports supplements often contain other ingredients than those listed on the label. Some athletes consume prohibited drugs without knowing."

Other studies have shown that 12 to 20 percent of products regularly used by athletes contain prohibited substances. Fr-chette observed a particular interest by the athletes on the efficiency, legality and safety of those drugs.

"No less than 81 percent of athletes taking supplements already had sufficient protein from their diet," says Fr-chette. "The use of multivitamins and minerals can make up for an insufficient intake of calcium, folate yet not for lack of potassium."

What's more, consumers of supplements had levels of sodium, magnesium, niacin, folate, vitamin A and iron that exceeded the acceptable norms. "This makes them susceptible to health problems such as nausea, vision trouble, fatigue and liver anomalies," says Fr-chette.

Source: University of Montreal