On Sept. 23, BMJ Group retracted a study suggesting that small daily quantities of apple cider vinegar might help people who are overweight or obese to lose weight.
The small clinical trial was initially published in BMJ Nutrition, Prevention & Health in March 2024. The findings generated widespread international attention and continue to be referenced in media.
According to BMJ, the retraction was prompted by “concerns raised about the quality of the work” including the approach to statistical analysis of the data, implausible statistical values, reliability of the raw data, inadequate reporting of methods and lack of prospective trial registration.
“In hindsight, this was the wrong decision to make. But the authors come from a scientific environment that is underrepresented in nutritional research, and the journal aims to prioritize high-quality evidence, which usually comes from clinical trials,” said Martin Kohlmeier, editor-in-chief of BMJ Nutrition, Prevention & Health. “These are relatively unusual in nutritional research as they can be challenging to undertake because of the numbers of participants and time needed to obtain meaningful results.”
Initially, concerns were raised in critiques of the study, some of which were published as letters in the journal. After a review from BMJ’s content integrity team, the study was referred to statistical experts for evaluation. The statisticians attempted—unsuccessfully—to replicate the data and identified “multiple analytical errors” and “irregularities in the data set.”
The study authors said the data errors were “honest mistakes,” but agreed with BMJ’s retraction.
“Tempting though it is to alert readers to an ostensibly simple and apparently helpful weight loss aid, at present the results of the study are unreliable, and journalists and others should no longer reference or use the results of this study in any future reporting,” said Dr. Helen Macdonald, publication ethics and content integrity editor at BMJ Group. “This retraction reflects our strategic and proactive approach to investigating concerns raised about the content we publish. We act where necessary in the interests of openness and the importance of correcting the scientific record.”
For more information, visit https://bmjgroup.com.
