New research offers a reminder that dietary supplements don't come without risks — and the problems they can cause appear to be on the rise.

A study published in the Journal of Medical Toxicology finds that U.S. Poison Control Centers receive a call every 24 minutes, on average, regarding exposures to dietary supplements.

The rate of calls increased by almost 50 percent from 2005 to 2012, the researchers found. A total of 274,998 cases were reported from 2000 through 2012.

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Seventy percent of the calls involved children younger than 6 years old. The majority of exposures were unintentional, occurring when children swallowed supplements they found at home.

About 4.5 percent of the time — more than 12,300 cases — serious medical complications occurred.

"Many consumers believe dietary supplements are held to the same safety and efficacy standards as over-the-counter medications," Dr. Gary Smith, senior author of the study and director of the Center of Injury Research and Policy at Nationwide Children's, said in a statement. "However, dietary supplements are not considered drugs, thus they are not required to undergo clinical trials or obtain approval from the FDA prior to sale, unless the product is labeled as intended for therapeutic use."

In almost half of the cases, miscellaneous substances found in commonly used dietary supplements accounted for the calls.

Botanical ingredients were to blame in nearly a third of cases, and hormonal products accounted for about 15 percent of the reported problems.

Serious medical complications occurred most frequently with botanicals, energy products, and what the researchers referred to as "cultural medicines."

Within the botanical category, yohimbe, which is derived from the bark of a West African evergreen tree, accounted for the majority of medical complications. The botanical, which is often used as an aphrodisiac, can cause heart beat rhythm changes, kidney failure, seizures, heart attack, and death.

Nearly 30 percent of yohimbe exposures resulted in moderate or major side effects.

Many of the exposures of energy products, including energy drinks, occurred in young children and led to heart and breathing problems, seizures, and other clinical problems.

For the study, the researchers analyzed detailed data from telephone calls about substance exposures received by regional poison control centers across the U.S.

The researchers said the study underscores the need for improved regulation, child-proof packaging, and parental education.

"Lack of federal oversight has led to inconsistencies in the quality of dietary supplements, product mislabeling and contamination with other substances," said Henry Spiller, a co-author of the study and director of the Central Ohio Poison Center at Nationwide Children's. "Although the majority of these exposure calls did not result in serious medical outcomes, exposures to yohimbe and energy products can be dangerous, suggesting the need for child-resistant packaging, caregiver education and FDA regulation of these substances."