Lawmakers investigating energy drinks have taken action since our December 12, 2012 post.

Yesterday, Rep. Ed Markey, D-Mass., and Sens. Dick Durbin, D-Ill., and Richard Blumenthal, D-Conn., sent letters to 14 energy drink companies, including 5-hour Energy, Pepsi Co., Celsius, Arizona Energy, Clif Bar, Fuze Beverage, Jamba, Monster Beverage, Coca-Cola, Red Bull, Rockstar, Sambazon, Target, and the Dr. Pepper Snapple Group asking the companies to explain their marketing claims and provide information about the ingredients in the products.

The complete list of letters can be found here.