The parents of a woman who died are suing Panera Bread over its caffeinated lemonade.

They say their 21-year-old daughter died from cardiac arrest a year ago after drinking the restaurant chain's "Charged Lemonade."

Sarah Katz, a University of Pennsylvania student from Jersey City, knew she had a heart condition known as Long QT syndrome. She took medication to control it and had to limit her caffeine intake.

The parents allege that the company failed to specify how much caffeine the drink had -- comparing it to that of a dark roast coffee.

Panera's website states that there are 390 milligrams of caffeine in a 30-ounce cup of the lemonade - slightly less than what the Food and Drug Administration says is safe for healthy adults.