New York's attorney general is investigating whether the multibillion-dollar energy-drink industry is deceiving consumers with misstatements about the ingredients and health value of its products. 
 
 Eric T. Schneiderman issued subpoenas in July to PepsiCo Inc., maker of AMP, Monster Beverage Corp., and Living Essentials LLC, maker of 5-hour Energy drink, according to a person familiar with the matter. The subpoenas asked for information on the companies' marketing and advertising practices. 
 
 The caffeine-heavy, carbonated beverages have become ubiquitous at grocery stores, gas stations and checkout counters across the country. Makers of the drinks, which are often sweetened with flavors such as grape or mixed berry, say they boost energy with a mix of additives including B-vitamins, taurine and ginseng. AMP's website, for example, says the B-vitamins and caffeine in its Boost drinks offers "the kick you need to tackle the early morning meeting." On its website, 5-hour Energy says it gives "hours of energy" with "no crash later." 
 
 The probe is the latest in a series of attention-getting moves by New York officials. In May, New York City Mayor Michael Bloomberg announced plans to restrict the sale of large sodas at restaurants, movie theaters and other locations, sparking criticism from the beverage industry. This month, New York's top banking regulator, Benjamin M. Lawsky, accused British bank Standard Chartered PLC of illegal dealings with Iranian entities, and the bank agreed to a $340 million settlement. 
 
 Energy drinks are among the fastest-growing products in the beverage sector. U.S. retail sales of the drinks rose 16% last year to $8.9 billion, accounting for 12% of the carbonated-soft-drink category, according to Beverage Digest, a trade publication and data service. Monster leads in the U.S. by volume, ahead of Austria's Red Bull GmbH and Rockstar Inc. 
 
 The drinks are regulated more loosely than traditional sodas such as cola. In 2009, the Food and Drug Administration said it was "concerned" certain ingredients such as botanical extracts were being added to beverages and foods beyond their traditional use, which it said raised questions about safety. The federal agency says the term "energy drink" isn't defined by any FDA regulation, describing it as an ill-defined marketing term with widely varying ingredients. 
 
 The New York probe is focused on whether the drink makers are misleading consumers with inaccurate labeling and advertising, according to the person familiar with the matter. The investigation is in the early stages and could expand to other companies, that person said. 
 
 Spokespeople for PepsiCo, Monster and Living Essentials declined to comment. 
 
 Investigators are examining whether the companies overstated the benefits of exotic-sounding ingredients while understating the role of caffeine, a common stimulant that industry critics believe to be the main active ingredient, that person said. 
 
 The products' labels often don't say how much caffeine is contained in the drink. The label on Monster's 16-ounce can says it contains caffeine but doesn't say how much; 5-hour Energy doesn't say how much caffeine is contained in one bottle, but its website says it is about as much as a cup of coffee. 
 
 The Monster spokeswoman said that on a per-ounce basis, Monster contains half the caffeine of some cups of coffee. "Monster energy drinks are completely safe, and we stand behind our products," she said in an email. AMP's label says it contains 10 milligrams per fluid ounce. 
 
 Investigators are looking into whether the addition of ingredients like guarana—another source of caffeine—violates laws that ban putting multiple sources of caffeine in one beverage without disclosing the overall amount, according to the person familiar with the investigation. 
 
 If energy-drink makers are found to have violated certain New York state laws regulating food and drugs, they could be forced to pay civil fines and penalties, and to change their labeling and marketing. 
 
 Enlarge Image Close Bloomberg New York state is probing the energy-drink industry over the ingredients and health value of the products. Above, cans of Monster. 
 
 While the FDA generally has jurisdiction to regulate food and drink safety, state attorneys general also have powers to investigate and regulate almost any product sold within the boundaries of their states. 
 
 California-based Monster disclosed in an Aug. 9 Securities and Exchange Commission filing that it received a subpoena in July as part of an unnamed state attorney general's probe into the "advertising, marketing, promotion, ingredients, usage and sale" of its energy drinks. 5-hour Energy disclosed in a July bond-offering memorandum a state attorney general recently requested documents about its product and marketing. 
 
 Those disclosures are related to the New York attorney general's probe, people familiar with the matter said. 
 
 Some scientists and health experts say energy drinks deliver all their kick from caffeine, and that other ingredients, while not appearing to be dangerous, are simply a marketing gimmick. It is safe for the average person to consume about 400 milligrams of caffeine per day, but overconsumption could cause heart problems, according to health experts. 
 
 "You're better off drinking a cup of coffee," said Tod Cooperman of ConsumerLab.com, which has conducted a chemical analysis of 5-hour Energy and other energy drinks. A study Mr. Cooperman conducted on 5-hour Energy found it contains 207 milligrams of caffeine, far more than a typical cup of coffee's 80-100 milligrams. "It's a stimulant," he said of 5-hour Energy. 
 
 —Matthieu Wirz contributed to this article. 
 
 Write to Reed Albergotti at reed.albergotti@wsj.com and Mike Esterl at mike.esterl@wsj.com 
 
 A version of this article appeared August 28, 2012, on page A1 in the U.S. edition of The Wall Street Journal, with the headline: New York Probes Energy-Drink Makers. ||||| The New York State Attorney General issued subpoenas in July to three firms that make energy drinks, including PepsiCo Inc, seeking information on the companies' marketing and advertising practices, a person familiar with the matter said on Tuesday. 
 
 Besides Pepsi, maker of AMP, Attorney General Eric Schneiderman also sent subpoenas to Monster Beverage Corp and Living Essentials LLC, maker of the 5-Hour Energy drink, said the source, who declined to be identified, citing lack of authorization to speak to the media. 
 
 A spokeswoman for Schneiderman declined to comment, as did PepsiCo. 
 
 Living Essentials also declined to comment beyond its July offering memorandum in which it said that it had recently received an inquiry from a state attorney general asking for documents relating to its product and marketing. 
 
 The company said in the memorandum, which was distributed in connection with a debt offering, that it was responding to the inquiry. 
 
 Monster also declined to comment beyond its August U.S. Securities and Exchange Commission where it stated that it had received a subpoena from an unspecified state attorney general. Coca-Cola and Dr Pepper Snapple, which make the NOS and Venom energy drinks respectively, said at the time that they did not receive subpoenas. 
 
 Schneiderman is examining whether the companies overstated the benefits of ingredients in the drinks while understating the role of caffeine, a common stimulant that industry critics believe to be the main active ingredient, the source said. 
 
 At least one Wall Street analyst found comfort in the narrow scope of the subpoenas. 
 
 "We think changes to labeling and marketing related to source of stimulant are unlikely to materially impact energy drink sales," Stifel Nicolaus analyst Mark Astrachan wrote in a research note. 
 
 Energy drinks, which can have less caffeine per ounce than strong coffee, make up a fast-growing sector of an otherwise stagnant market for carbonated soft drinks. 
 
 Monster is the leading U.S. energy drink by volume with nearly 39 percent of the U.S. market, but Austria's Red Bull has the highest share by revenue, due to its premium price. 
 
 The latest move on the energy drink industry follows New York City Mayor Michael Bloomberg's plan to propose a far-reaching municipal ban on sales of large-size sugary beverages by restaurants, mobile food carts, movie theaters and delis. 
 
 Monster shares were down less than 1 percent at $59.51 in afternoon trade on the Nasdaq. PepsiCo was up 2 cents at $73.19 on the New York Stock Exchange. 
 
 (Additional reporting by Joy Ferguson in New York and Sakthi Prasad in Bangalore; Editing by David Holmes and Dan Grebler)
– New York state's attorney general apparently is a little skeptical about the wonder claims of three popular energy drinks. Eric Schneiderman issued subpoenas to three big players—Monster Beverage; PepsiCo, maker of AMP; and Living Essentials, maker of 5-Hour Energy drink, report the Wall Street Journal and Reuters. The subpoenas request information about how the companies market the drinks, which are carbonated and high in caffeine. Critics say the drinks provide all their boost thanks to that caffeine, even if advertisements would lead you to believe it's a result of added vitamins and other healthy-sounding ingredients. Energy drinks are big money-makers for the soft-drink industry, but they're also more loosely regulated than traditional soda, notes the Journal. "You're better off drinking a cup of coffee," says one analyst of the beverages at ConsumerLab.com.