Q. Are energy drinks helpful for enhancing my teenager's sports performance?

A. Red Bull, Jolt and similar drinks are marketed as ways to increase energy, improve concentration and enhance sports performance. Their main ingredients are sugar and caffeine. Eight ounces of most energy drinks contain 6 to 10 teaspoons of sugar and the caffeine equivalent of one to two cups of strong coffee.

The combination of sugar and caffeine gives energy-drink gulpers a quick burst of energy but often causes an energy crash later, leaving you feeling more tired than before.

Over time, repeated infusions of caffeine and sugar can contribute to blood sugar imbalances, overproduction of adrenaline and excess sugar being converted to fat in the body. This works against our body's natural mechanisms for providing energy and protecting health. We shouldn't do lasting damage to our internal energy machinery just for a short-term energy fix.

These drinks also can be addicting. If you drink them often, you start needing larger amounts to feel their effects. Eventually, without them you feel weak and tired. Then you need the energy drinks just to feel normal. The process is similar to drug addiction.

There is little research on the health effects of energy drinks in kids and teens, who are more sensitive to caffeine's effects than adults. Caffeine causes jitters, anxiety, moodiness and sleep disturbances in some kids. Caffeine also removes calcium from the bones which may increase the risk of fractures.

Some teens use energy drinks before and after sports to hydrate themselves. But in fact, the combination of sugar and caffeine slows the body's ability to absorb water, dehydrating the body.

For exercise that lasts less than 90 minutes, water is the best drink for rehydration. For longer bouts of activity, sports drinks such as Gatorade and Powerade may be useful — they replace fluids, carbohydrates and minerals lost during intense activity and don't contain caffeine.

At a time when professional athletes are under scrutiny for using performance-enhancing stimulants and muscle builders, using energy drinks sends keiki and teens the wrong message, teaching them they need something artificial to succeed.

Eating healthful foods is the best way to give your teen's body energy. Eating a variety of energy-producing carbohydrates, lean proteins and healthy fats provide long-lasting energy and nutrients that heighten alertness. This, combined with hard work and training, should improve performance without sacrificing health.

Amy Tousman is a registered dietitian with the Health Education Center of Straub Clinic & Hospital. Hawai'i experts in traditional medicine, naturopathic medicine and diet take turns writing the Prescriptions column. Send your questions to: Prescriptions, Island Life, The Advertiser, P.O. Box 3110, Hono-lulu, HI 96802; islandlife@hono luluadvertiser.com; or fax 535-8170. This column is not intended to provide medical advice.