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A systematic review and quality assessment of case reports of adverse events for borage (Borago officinalis), coltsfoot (Tussilago farfara) and comfrey (Symphytum officinale)


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Avila, C, Breakspear, I, Hawrelak, J ORCID: 0000-0002-7436-9666, Salmond, S and Evans, S ORCID: 0000-0003-2606-2990 2020 , 'A systematic review and quality assessment of case reports of adverse events for borage (Borago officinalis), coltsfoot (Tussilago farfara) and comfrey (Symphytum officinale)' , Fitoterapia, vol. 142 , pp. 1-12 , doi: 10.1016/j.fitote.2020.104519.

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Symphytum officinale (comfrey), Tussilago farfara (coltsfoot) and Borago officinalis (borage) have long histories oftherapeutic use, but their safety has been questioned due to the presence of unsaturated pyrrolizidine alkaloids(PAs). The evidence base underlying these concerns relies in part on case reports. This systematic review assessesthese case reports for their reliability to inform this debate.Method: Study selection was restricted to case reports describing possible pyrrolizidine alkaloid related harmand ingestion of comfrey, coltsfoot or borage. An extensive search of academic databases was conducted. Papersmeeting the criteria were critically appraised.Results: The search resulted in 11 appropriate case reports, none of which involved borage. Nine reports wereassessed for causality and indicated some degree of association between the material ingested and the adverseevent. Lack of unequivocal identification of the species ingested compromised attribution and was a significantsource of uncertainty. Three levels of identity confusions were found; misidentification or substitution at thelevel of the whole herb; omission of appropriate botanical identification and attribution of a specific PA to eithercomfrey or coltsfoot when it is a constituent found in other plants of established toxicity.Conclusion: These cases are an unreliable body of evidence on which to draw conclusions about the safety of theoral consumption of Symphytum officinale and Tussilago farfara. Toxicological studies based on oral ingestion ofphytochemically-complex preparations of these herbs may be the most accurate methodology for assessingclinical risk.

Item Type: Article
Authors/Creators:Avila, C and Breakspear, I and Hawrelak, J and Salmond, S and Evans, S
Keywords: adverse events, borage, coltsfoot, comfrey, pyrrolizidine alkaloids, systematic review
Journal or Publication Title: Fitoterapia
Publisher: Elsevier Science Bv
ISSN: 0367-326X
DOI / ID Number: 10.1016/j.fitote.2020.104519
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© 2020 The Author(s). Licensed under Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (CC BY-NC-ND 4.0)

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