By Amy Norton
WEDNESDAY, Oct. 14, 2015 (HealthDay News) -- Side effects from dietary supplements send more than 20,000 Americans to the emergency room each year, a new government study reveals.
One expert said the report -- published Oct. 15 in the New England Journal of Medicine -- should quash arguments that herbal products, amino acids and other supplements are uniformly "safe" and need no tighter regulation.
"This is the most important study done on dietary supplements since DSHEA was passed," said Dr. Pieter Cohen, an assistant professor at Harvard Medical School who studies supplement safety.
Cohen was referring to the Dietary Supplement Health and Education Act, a 1994 law that defined supplements as food rather than drugs. The upshot is that manufacturers do not have to prove their products have benefits, or are even safe.
Over the years, there have been recalls of certain supplements found to cause harm, said Dr. Andrew Geller, a researcher at the U.S. Centers for Disease Control and Prevention, who led the new study.
Often, those products were tainted with banned pharmaceutical ingredients, according to background notes in the study.
"But there's been little data on how often supplements not involved in those recalls cause harm," Geller said.
To get an idea, his team studied records from 63 U.S. emergency departments taking part in a national injury surveillance system project. The investigators found that between 2004 and 2013, almost 3,700 children and adults arrived at the ER with a side effect attributed to a dietary supplement.
Nationwide, that would translate to 23,000 ER visits each year, Geller's team estimated. And roughly half of those patients would be children or young adults, Geller said.
Typically, children were taken to the ER because of accidental ingestion of a vitamin or other supplement, the study found.
But when adults in their 20s or 30s landed in the ER, it was frequently related to supplements marketed for weight loss or boosting energy, Geller said.
Those supplements -- which include ingredients like caffeine, ginseng, guarana (a plant high in caffeine) and linoleic acid -- were often tied to cardiac effects, such as heart palpitations and chest pain.
In fact, weight-loss products and energy boosters accounted for nearly 72 percent of heart-related problems linked to a dietary supplement, the study found.
Most often, people suffered no lasting harm. Even among those with heart-related symptoms, 90 percent were sent home from the ER, the findings showed.
"But," Geller said, "we estimate that over 2,100 people are hospitalized each year."
And that is likely an underestimate, he added, since many adverse reactions to supplements may go undetected.
Cohen, who wasn't involved in the study, agreed.
"It's well known that doctors don't ask people about their supplement use," Cohen said. "And it's well known that patients don't bring it up."
The U.S. Food and Drug Administration has limited authority over dietary supplements. It can take action if a product on the market is found to be unsafe, for example.
But that system, Cohen said, relies on doctors and consumers to submit reports of harm from supplements.
Also, supplement labels don't have to carry information about side effects. Nor is there any guarantee that the product contains the ingredients listed on the label -- and only those ingredients, Cohen added.
In a study published this year, he and his colleagues found that nearly a dozen supplements marketed for weight loss were "spiked" with an amphetamine-like substance called BMPEA.
Cohen said he was "not surprised at all" that supplements marketed for weight loss and energy were commonly tied to ER visits in this study.
According to Geller, the findings should help zero in on the types of supplements that deserve more scrutiny.
But one of the problems, Geller said, is that many supplements contain a mix of ingredients whose actions in the body are unclear. So it can be hard to pinpoint the culprit behind any side effects.
For now, Cohen suggested that consumers avoid such combination supplements. "If you want echinacea, buy echinacea," he said, referring to the herb that many people believe fights colds.
To find information on the science behind a product, Cohen recommended the U.S. National Institutes of Health website on dietary supplements.
The U.S. National Center for Complementary and Integrative Health talks about using supplements wisely.