BMJ Group retracts apple cider vinegar weight-loss trial

BMJ Group has retracted a study that reported weight loss from small daily amounts of apple cider vinegar, saying the results cannot be supported by the data and should no longer be used in reporting ^[2].

The trial was published in BMJ Nutrition, Prevention & Health in March 2024 under the title "Apple cider vinegar for weight management in Lebanese adolescents and young adults with overweight and obesity: a randomised, double-blind, placebo-controlled study" ^[1][2]. Participants took 5, 10 or 15 mL of apple cider vinegar, or a placebo, each day for 12 weeks ^[1]. Reported weight loss reached as much as 7 kilograms over those 12 weeks ^[1]. A press release went out with the paper, and the findings drew widespread international attention ^[1][2].

Joe Schwarcz, writing for McGill University's Office for Science and Society, said he read the paper closely and noticed two oddities. There was little dose-response: the groups taking 5 mL and 10 mL had very similar weight loss. And the amount lost — as much as 7 kilograms in 12 weeks — was the kind of number normally seen with Ozempic and Wegovy, the GLP-1 drugs used for weight loss ^[1]. He wrote that there was no apparent physiological explanation for how vinegar could cause that effect ^[1].

Within a couple of weeks, letters to the editor began questioning the quality of the research and the size of the weight loss. The criticism mounted, and the journal sought an independent review by experts, who found flaws in the procedure and concluded that the statistics had been improperly analyzed and that the results could not be supported by the data. The journal retracted the paper about a year after publication ^[1].

The retraction notice lists the concerns behind the decision: the approach to statistical analysis, implausible statistical values, the reliability of the raw data, inadequate reporting of methods, and the lack of prospective trial registration, which the publisher says breaches its editorial policy ^[2]. The paper went to BMJ Group's content integrity team and then to statistical experts, who tried to replicate the results and examine the authenticity of the underlying data ^[2]. The statisticians could not replicate the results and identified multiple analytical errors, along with irregularities in the data set. Their report, appended to the retraction notice, concluded that data collected from each participant would require further independent scrutiny ^[2]. The authors said the errors were honest mistakes but agreed with the decision to retract the study ^[2].

"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, BMJ Group's publication ethics and content integrity editor ^[2].

Professor Martin Kohlmeier, editor in chief of BMJ Nutrition Prevention & Health, said that publishing the study without trial registration was, in hindsight, the wrong decision, and noted that the authors came from a scientific environment underrepresented in nutrition research ^[2].

Why it matters for patients

For anyone weighing vinegar against prescription treatment, the 7-kilogram figure was the reason this study mattered: it was comparable to results seen with GLP-1 drugs such as Ozempic and Wegovy, which are semaglutide ^[1]. That comparison no longer rests on a trustworthy trial ^[2].

The retraction does not show that apple cider vinegar has no effect on weight. It means this trial provides no dependable evidence either way, and whether vinegar affects weight has not been established by this research. Products, posts and videos that cite the study are relying on findings the publisher says should not be used ^[2]. McGill's account notes that proponents of apple cider vinegar still make extravagant claims for it ^[1].

The episode also shows how long a flawed paper can stand. Publication was in March 2024, problems surfaced through reader letters, and retraction came about a year later ^[1][2]. Schwarcz wrote that he used to mention the study in his lecture on weight control and now uses it instead as an example of why to stay skeptical even of peer-reviewed research ^[1].

What happens next

The statisticians' report is appended to the retraction notice, and BMJ Group says the study's results should not be cited in future reporting ^[2]. Macdonald said such investigations are often complex — this one involved detailed scrutiny of data and correspondence with researchers, institutions and other experts — and that reaching a sound final decision can take several months ^[2]. Any further action by the authors' institutions has not been reported. In 2025, a Netflix series titled "Apple Cider Vinegar" brought additional attention to unproven wellness claims about the product ^[1].