Caffeine and kids: A safe mix?

Caffeine-infused waffles and maple syrup are being promoted as energizing alternatives to a morning mug of coffee.

But the recent craze of adding caffeine to a range of kid-friendly snack foods — including popcorn, chewing gum, candy bars, mints, Cracker Jack, jelly beans and ice cream — is raising enough concern that the U.S. Food and Drug Administration (FDA) has launched an investigation of caffeine's possible health effects on children and adolescents.

The effort, which comes amid the heated debate over whether energy drinks with stimulants are safe for children, marks the agency's first close look at the world's most popular psychoactive drug since its use in cola was approved in the 1950s.

Most healthy adults can safely tolerate moderate doses of 200 to 300 milligrams, which is about two to four cups of brewed coffee, the National Institutes of Health said. But the United States lacks official guidelines or limits for children, whose smaller bodies and developing brains may be more vulnerable to caffeine's effects, including the risk of physical dependence and addiction.

Part of what worries the FDA is the changing nature of how caffeine is delivered — through a greater array of products that may appeal to younger consumers and in higher doses than in the past.

Chewing a pack of Jolt Energy Gum, for example, would have effects similar to downing six energy drinks, according to the package.

"It's a question of finding caffeine in new and different places," said Michael Taylor, the FDA's deputy commissioner for food. "There are concerns over the perhaps subtle developmental impacts on kids and whether they become regular users of a central nervous system stimulant. What are the cumulative effects?"

Proponents say caffeine has been safely consumed in foods and beverages for centuries. Many of the newly caffeinated snacks target adults who want a quick pick-me-up but don't like coffee.

Consumed daily by 80 percent of the world, caffeine is a bitter-tasting nervous system stimulant that occurs naturally in coffee, tea, guarana and kola nuts. It's thought to work by interfering with a brain chemical called adenosine that facilitates sleep.

"It not only wakes up the brain, but it can increase heart rate," said Dr. Lynn Goldman, a pediatrician and dean of the School of Public Health and Health Services at George Washington University. "When I've seen people with caffeine overdose, they're scared; they end up in the ER because they think they're having a heart attack."

In adults, caffeine use is relatively safe. But the American Academy of Pediatrics recommended in 2011 that children and teens steer clear of caffeinated drinks because caffeine interferes with sleep and can contribute to anxiety, in addition to an increased heart rate.

"Childhood and adolescence is a period of rapid growth in the final stage of brain development; proper sleep and nutrition are essential," said Jennifer Temple, an assistant professor in the School of Public Health and Health Professions at the University of Buffalo who studies children's caffeine use. "Caffeine disrupts sleep patterns, and the excess consumption of soda is associated with poor diet, excess weight and cavities."

Sales of energy drinks grew by 78 percent from 2006 to 2011, according to the market research firm Mintel, and a recent study in the journal Pediatrics found that half of the energy drink market consists of children, adolescents and young adults.