Energy drinks, under investigation by the Food and Drug Administration (FDA) after reports of deaths and serious injuries, offer little or no benefit to consumers, experts say.

According to The New York Times, energy drinks sales topped more than $10 billion in 2012 in the United States. While the companies that make the drinks advertise their products as providing a mental and physical edge, a cup of coffee has the same effect, experts told the newspaper.

The drinks, such as Red Bull, Monster Energy and Rockstar Energy, claim the drinks are specially engineered. U.S. Representative Edward Markey of Massachusetts has asked the federal government to investigate the industry’s marketing claims.

“These are caffeine delivery systems,” Dr. Roland Griffiths of Johns Hopkins University, who has studied energy drinks, told the newspaper. “They don’t want to say this is equivalent to a NoDoz because that is not a very sexy sales message.”

In 2011, the Substance Abuse and Mental Health Services Administration issued a report that found a sharp rise in the number of emergency department visits linked with the use of non-alcohol energy drinks, from 1,128 visits in 2005, to 13,114 in 2009.

The report noted that energy drinks are marketed to appeal to youth, and are consumed by up to half of children, teenagers and young adults.

The FDA said it has not established a connection between energy drinks and the reported deaths. The FDA can regulate caffeine levels in soft drinks. The limit in a 12-ounce soda is about 71 milligrams. The caffeine levels in most energy drinks exceed that level, because they are labeled dietary supplements.