Research into the hazards and risks of taking dietary supplements should be a priority, according to US researchers who assessed the adverse events caused by natural supplements.
The report looked at the role played by dietary supplements in adverse events recorded by 11 poison control centres in the US during 1998. The researchers said that out of more than 2,300 calls about dietary supplements, almost 500 people had symptoms probably caused by a supplement. One third of these supplement-related problems were moderate or severe, they noted.
The authors of the research, published in the 11 January issue of The Lancet, urged that a better surveillance system be set up, and a register of all supplement ingredients be available to the poison centres.
The researchers used a multitiered review process to select 489 cases for whom they were at least 50 per cent certain that their negative events were associated with dietary supplements. They set out to assess the effects of multiple ingredients and long-term use, and gathered data for patterns of use and information resources.
They noted both new and previously reported associations that included heart attack, liver failure, bleeding, seizures, and death. Increased symptom severity was associated with use of several ingredients, long-term use, and age. Paediatric exposures were more often unintentional than were adult ingestions, and treatment of disease was the reason for supplement use in at least 28 per cent of reports.
The authors said that dietary supplements are associated with adverse events of all levels of severity, organ systems, and age groups. Associations between adverse events and ingredients are difficult to verify if a product has more than one ingredient, and because of incomplete information systems, they explained.
"As a minimum, the difficulties we have described suggest the need for a comprehensive register of dietary supplements, strengthened surveillance (particularly mandatory reporting of adverse events), enforceable definitions of what constitutes a risk to safety, and what circumstances warrant product recall," they concluded.
The findings also "warrant concern" about the lack of child-resistant packaging on supplements, the study authors added. There were 48 cases involving children who accidentally took a supplement among the reports of adverse symptoms, they said.