Federal officials announced a crackdown on the dietary supplements industry Tuesday, targeting firms that falsely claimed their pills could help people lose weight, build muscle or even kick drugs.

The Justice Department said it had filed criminal charges against Dallas-based USPlabs, known for workout and weight-loss supplements such as Jack3d and OxyElite Pro. USPlabs allegedly told some retailers that its products contained natural plant extracts, but the company actually used a synthetic stimulant manufactured in a Chinese chemical factory, according to the department’s complaint.

Four unnamed people related to the USPlabs case were arrested Tuesday, and two more are expected to surrender, according to the Justice Department.

“The USPlabs case and others brought as part of this sweep illustrate alarming practices the department found — practices that must be brought to the public’s attention so consumers know the serious health risks of untested products,” Principal Deputy Assistant Attorney General Benjamin C. Mizer said in the announcement.

A USPlabs spokesman could not be immediately reached for comment.

Justice officials said the department had worked with other federal officials, including at the Food and Drug Administration, Federal Trade Commission and the U.S. Anti-Doping Agency, over the past year to bring civil and criminal cases against more than 100 makers and marketers of dietary supplements.

As part of those efforts, the FTC said it had filed a federal lawsuit against Florida-based Sunrise Nutraceuticals, accusing it of falsely claiming that its dietary supplement Elimidrol could help someone with opiate withdrawals. The company allegedly said Elimidrol was the No. 1 opiate withdrawal supplement and was the only opiate withdrawal product “guaranteed to work,” according to the FTC.

“Sunrise Nutraceuticals admits no wrongdoing, but at this time is cooperating with the FTC and has chosen to discontinue its claims regarding symptoms of opiate withdrawal,” the company said in a statement. “Sunrise Nutraceuticals will continue to focus on providing high-quality products that exceed its customers’ expectations.”

The industry has been criticized for some time. In April, more than a dozen state attorneys general asked Congress to launch an investigation into herbal supplements. A recent study in the British Journal of Cancer found a potential connection between men who took muscle-building supplements and the risk of developing testicular cancer. The New York attorney general’s office ordered four retailers — GNC, Target, Walgreens and Wal-Mart — to halt sales of some supplements after DNA tests apparently showed that they did not always contain the herbs advertised.

GNC was not named in Tuesday’s announcement, but the mere speculation that a federal probe would touch on supplements sent its stock plummeting 20 percent before recovering most, though not all, of its losses, finishing the day down 6.4 percent.

Health experts have long complained that supplements, which are not considered a food or a drug, are too loosely regulated and pose a safety hazard to consumers. Companies are required to ensure that products are safe and accurately labeled, experts say, but there is little federal oversight. The industry has countered that problems are contained among a few bad actors and do not reflect an industry-wide problem.

The Council for Responsible Nutrition, a trade group for the dietary supplement industry, applauded the federal action. CRN had previously reached out to the Justice Department “noting our concerns that companies engaging in blatant criminal activity were presenting a serious public health risk and hijacking the credibility of the reputable industry,” Steve Mister, the group’s president and chief executive, said in a statement. “These actions both help consumers navigate the market to avoid products that may do them harm, and also level the playing field for responsible companies who do things right.”

The FDA does have some authority to oversee dietary supplements but not nearly the strict regulatory power that it has over pharmaceutical drugs.

One critical difference is that dietary supplements do not need FDA approval before hitting the market. Except in rare cases, firms do not need to provide the agency with evidence showing that supplement ingredients are safe or actually work.

Manufacturers have to adhere to certain labeling requirements, such as including the name of the manufacturer, a list of ingredients and identifying the product as a “supplement.”

Supplement-makers also have a legal responsibility to ensure the safety of their products. But unlike with traditional drugs, which must undergo a series of clinical trials to prove they are safe and effective, the FDA has little means of flagging suspect supplements before they hit the market. In fact, when problems arise, the FDA is responsible for showing that a dietary supplement is unsafe before it can pull it from store shelves.

A study published last month in the New England Journal of Medicine detailed how diet pills, energy boosters and other supplements send an estimated 23,000 people to emergency rooms each. Most of those patients are young adults, children or the elderly. The visits commonly involved heart problems related to weight loss or energy supplements.

Dietary supplements are used by an estimated 150 million Americans, or more than half of U.S. adults, according to the Council for Responsible Nutrition, which represents the $35 billion industry.

Pieter Cohen, Harvard Medical School professor and expert in the dietary supplement industry, said the good news about Tuesday’s action was that it showed the government’s willingness to take on large companies in the industry.

“The bad news is it just reinforces that the current laws make no sense,” Cohen said. Companies can still legally market supplements for any range of health issues, without having to notify federal regulators. Only after people get harmed does the government step in. “The FDA is left in the position of playing catch up,” he said.

Joshua Sharfstein, a public health expert at Johns Hopkins University and a former FDA deputy commissioner, said the sweep detailed Tuesday showed the willingness of federal regulators to pursue complicated cases despite the current lack of oversight.

“FDA is constantly playing an after-the-fact role in dietary supplements,” said Sharfstein, who has written about the need for tighter regulation of the industry. “If the agency had more authority and the right kind of authority, it could far better protect consumers. I think a case like this shows that they’re really interested in protecting consumers in this area.”