Barry Meier / New York Times News Service

Three Democratic lawmakers Thursday sent letters to 14 marketers of highly caffeinated energy drinks requesting information about the products’ ingredients and any company studies showing their risks and benefits to children and young people.

In recent months, the Food and Drug Administration has begun examining the safety of energy drinks after reports of several deaths and injuries potentially associated with the products. The number of annual emergency room visits involving the drinks doubled from 2007 to 2011, according to a federal report released last week.

In addition, claims by drink producers that their proprietary formulations give consumers a physical and mental edge are coming under scrutiny. There is little scientific evidence, researchers say, that the drinks provide anything more than a high dose of caffeine similar to that in a cup of strong coffee.

The letters were sent by Sens. Richard Durbin of Illinois and Richard Blumenthal of Connecticut and Rep. Edward Markey of Massachusetts to companies including Monster Beverage, Rockstar, Red Bull and Living Essentials, the distributor of 5-Hour Energy.