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'I have learnt so much from indigenous and traditional approaches to health’ – Dr Vivien Rolfe [Interview]
Dr Vivien Rolfe is a gut physiologist who specialises in herbal and nutritional interactions with the human body.
Industry groups have criticised research questioning the safety of six herbal supplement ingredients, calling into question the robustness of data, approach, conclusions, and call to action.
Published in the JAMA Network Open journal, the paper estimated that 15.6 million adults in the US consumed at least one botanical product with liver liability within the previous 30 days.
According to the researchers, this figure was comparable with the number of people who consumed nonsteroidal anti-inflammatory drugs and a commonly prescribed hypolipidemic drug.
“Given a lack of regulatory oversight on the manufacturing and testing of botanical products, clinicians should be aware of possible adverse events from consumption of these largely unregulated products,” the study authors wrote.
The claims drew a scathing response from leading trade associations. The Council for Responsible Nutrition (CRN) rejected the “alarmist headlines” generated by the study’s findings about the six herbal supplement ingredients: turmeric, green tea extract, Garcinia cambogia, black cohosh, red yeast rice, and ashwagandha.
Putting the results in perspective, Steve Mister, president and CEO of the CRN, said: “This analysis of existing National Health and Nutrition Examination Survey (NHANES) survey data doesn’t appreciate that the overall risk these ingredients pose is exceedingly low.
“Revealing that more than 15 million Americans use at least one of these herbal supplements, when compared to their actual reported risks, only strengthens the case for their safety.”
The investigation, led by a University of Michigan team, looked at the NHANES data to identify frequency of botanical use in the US, where they extrapolated population estimates from the 2020 US Census.
Among the 9,685 adults enrolled in the NHANES cohort, the team noted the prevalence of use within the past 30 days was 7.5% for herbal dietary supplements overall and 4.7% for the six botanicals classified as potentially hepatotoxic.
Additional results from the Drug Induced Liver Injury Network suggested that the proportion of hepatotoxicity cases from herbal dietary supplements has grown concurrently with increased supplement use, “nearly tripling from 7% in 2004 to 2005 to 20% in 2013 to 2014”.
Focusing on the study’s methodology, the CRN added: “[It] does not investigate a causal relationship between consuming these botanical supplements and liver damage, nor does it add any new scientific findings with respect to their potential for hepatotoxicity.”
In similar sentiments, more industry groups called into question the study’s description of dietary supplement regulation in the US as well as the claim that the industry is largely “unregulated”.
The Consumer Healthcare Products Association (CHPA) went as far as submitting a letter to JAMA Network Open underscoring the study's significant inaccuracies and methodological limitations.
“The authors’ claim that the FDA does not require manufacturers to verify the ingredients in a product is incorrect,” said Duffy MacKay ND, the CHPA’s senior vice-president of dietary supplements.
“FDA regulations mandate identity testing of all incoming ingredients, in-process testing, and finished product testing to ensure quality and safety.”
The CHPA also highlighted the authors’ reference to a $150-billion figure for dietary supplement marketplace sales, with Mackay saying that this figure appeared to include broader economic impacts such as job creation and taxes, rather than direct marketplace sales.
According to market research, the annual US marketplace sales for dietary supplements has been estimated between $35.7 billion and $50 billion.
The study also attracted the attention of independent researcher Mardi Crane-Godreau, who suggested the paper lacked data on hepatotoxicity, doses, and common contaminants of subject botanicals.
“Two of the botanicals mentioned in the article, green tea and turmeric, are culinary products consumed by millions if not billions of consumers worldwide on a daily basis,” said Dr Crane-Godreau, who is principal at Bodymind Science LLC and a former assistant professor at Dartmouth Geisel School of Medicine.
“This study does not report indicate quantities of the consumed products that raise concern. Given that these two products are mainstays of the diet in many Asian and African countries, culinary consumption likely far exceeds the quantities consumed by most individuals as health promoting supplements.
“It is interesting to note that media have reported that some culinary turmeric is contaminated by products used to enhance its colour. It is not known if this may occur in turmeric used in supplements.”