WASHINGTON, DC, USA (Xinhua) — An estimated 23,000 hospital emergency rooms visits in the United States every year are due to adverse events related to dietary supplements, a new study has found.

These visits resulted in an estimated 2,154 hospitalisations annually in the country, where neither safety testing nor government approval is required before the marketing of dietary supplements, said the study published last week in the New England Journal of Medicine.

Dietary supplements have increased dramatically in the US market, from 4,000 products in 1994 to more than 55,000 in 2012, the most recent year for which data are publicly available, according to background information in the report.

About half of all adults in the United States reported having used at least one dietary supplement in the past month, such as herbals, amino acids, vitamins, and minerals.

That led to a US$14.8 billion expenditure for herbal or complementary nutritional products in 2007, or one-third of the out-of-pocket expenditures for prescription drugs.

The new study, led by Andrew Geller of the Centers for Disease Control and Prevention, reviewed nationally representative surveillance data from 63 emergency departments obtained from 2004 through 2013.

It found more than a quarter (28 per cent) of the 23,000 emergency visits for supplement-related adverse events involved young adults between the ages of 20 and 34 years.

Weight-loss or energy products caused more than half the visits in the age group, commonly for cardiac symptoms such as palpitations, chest pain, and tachycardia.

Unsupervised ingestions by children also accounted for more than one-fifth (21 per cent) of the emergency visits, with almost two-thirds involving micronutrients.

“Innovative safety packaging and targeted education on safe storage are potential interventions to reduce unsupervised ingestion of supplements by children,” the study said.

Among older adults, swallowing problems caused nearly 40 per cent of emergency department visits for supplement-related adverse events, with micronutrients implicated in more than 80 per cent of these visits.

“The FDA (Food and Drug Administration) recommends limiting the size of pharmaceutical tablets to 22 mm and requires the reporting of tablet size and shape on abbreviated new-drug applications,” it explained. “However, there are no size recommendations or similar reporting requirements for dietary supplements. Large amounts or multiple types of micronutrients are often packaged in a single large pill.”

In a response to the study, the trade association Council for Responsible Nutrition said the results only “reinforce that dietary supplements are safe products, particularly when put into context with the number of people — over 150 million Americans — who take dietary supplements every year.”

“To put this projected number of 23,000 annual emergency room visits into context, we estimate that far less than one-tenth of one per cent of dietary supplement users experience an emergency room visit annually,” it added.