Inquiries about supplement-drug interactions on rise, ABC says

By Hank Schultz contact

- Last updated on GMT

Actual adverse events attributed to supplement-drug interactions are rare. Nevertheless, inquiries about the risks are on the rise, according to the American Botanical Council.

ABC chief science officer Stefan Gafner, PhD, spoke with NutraIngredients-USA at the recent Oxford International Conference on the Science of Botanicals at the University of Mississippi. The conference was put on by the National Center for Natural Products Research.

Gafner said ABC has received a rising tide of inquiries about potential interactions. Most of these are coming from practitioners, Gafner said, which could speak to ABC’s rising profile over the years as a clearinghouse for information about botanicals.

“What I’ve seen is health care professionals who ask about particular dietary supplements and their potential to interact with conventional drugs,”​ Gafner said.

While there is more recognition on the part of these professionals that such interactions are possible, Gafner said there is still an incomplete understanding of what’s important and what’s just noise.

“There is a lot of confusion about what are meaningful interactions and what is data out there in the public domain that doesn’t necessarily relate to a problem for the consumer,”​ he said.

JAMA study muddied waters

In 2016, JAMA published a paper​ in which scientists from the University of Illinois at Chicago reported that concurrent use of at least five prescription medications increased from 30.6% in 2005-6 to 35.8% in 2010-11, while concurrent use of five or more medications or supplements of any type increased from 53.4% to 67.1%. The use of dietary supplements increased from 51.8% to 63.7%, they added. 

“These findings suggest that the unsafe use of multiple medications among older adults is a growing public health problem. Therefore, health care professionals should carefully consider the adverse effects of commonly used prescription and nonprescription medication combinations when treating older adults and counsel patients about these risks,”​ the authors concluded. 

In speaking to NutraIngredients-USA at that time, Dr Rick Kingston, president of regulatory and scientific affairs at SafetyCall International and clinical professor of pharmacy at the University of Minnesota, said that the authors seem to suggest that because we see an increase in the use of dietary supplements that equates to an increased risk or toxicity, “and that’s not true”. 

“There is evidence to show that increased use of targeted dietary supplements in practice results in better health outcomes,” ​he said. “I don’t think you can equate a greater use to a greater risk.”​ 

“Also, the pharma databases I’ve examined seem to over-warn on the potential interactions, but the supporting data is often weak, inconclusive, conflicting or non-specific,” ​he added. 

Ginkgo, turmeric top recent concerns

Gafner said that inquiries often come in relating to ginkgo and turmeric. Piperine figured into the practitioners’ concerns as well. Is this because there are legitimate toxicological concerns with these ingredients, or is it more of an artifact of the ingredients’ popularity? While Gafner did not seek to brush the concern under the rug, he was inclined to the view that the expansion of the market had a lot to do with the increase in inquiries.

“These are ingredients that are some of the top sellers. So more people show up that use these ingredients,​” he said.

Gafner said there is a need for more research on the topic, in particular studies done in vivo. And he said new rapid screening tools are called for, because it is impossible to test all of the combinations of every commonly used ingredient against every commonly used drug.

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