Some credit due to pulling the study but not before false information went viral
By BMJ Group
Journalists and others should stop referencing or using
the study’s findings in any future reporting.
BMJ Group has withdrawn a study that once suggested drinking
small amounts of apple cider vinegar each day could support weight loss in
people who are overweight or obese.
The clinical trial, published in March 2024 in the
open-access journal BMJ Nutrition, Prevention & Health, was
accompanied by a press
release and quickly drew widespread international attention. Even
months later, its claims continued to be cited in media reports.
The decision to retract the paper came after serious
concerns were raised about its quality. Issues included questionable methods of
statistical analysis, implausible statistical outcomes, unreliable raw data,
insufficient detail in the description of methods, and the absence of prior
trial registration (a requirement under BMJ Group’s editorial policy).
Early doubts appeared in critiques of
the research, with some published as letters in the journal.
BMJ Group’s content integrity team then conducted a review and referred the
work to independent statistical experts. Their task was to test whether the
results could be replicated and to verify the validity of the data submitted by
the authors.
Review Findings
It wasn’t possible for the statisticians to replicate the
results and multiple analytical errors were identified. There were also
irregularities in the data set, and their report, which is appended to the
retraction notice, concluded that the data collected from each participant
would require further independent scrutiny.
The authors said that the identified errors were honest
mistakes, but they agree with the decision to retract the study.
Dr. Helen Macdonald, Publication Ethics and Content
Integrity Editor at BMJ Group, said: “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.”
She added: “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.
“While we deal with allegations as swiftly as possible, it’s
very important that due process is followed. Investigations are often complex.
This one involved detailed scrutiny of data and correspondence with
researchers, institutions, and other experts, for example. Reaching a sound and
fair and final decision can therefore take several months.”
Reflection on Publication Decision
Commenting on the decision to publish the study despite the
lack of trial registration, Professor Martin Kohlmeier, editor in chief of BMJ
Nutrition Prevention & Health, explained: “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.
“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.”
Reference: “Apple cider vinegar for weight management in
Lebanese adolescents and young adults with overweight and obesity: a
randomised, double-blind, placebo-controlled study” 23 September 2025, BMJ
Nutrition Prevention & Health.
DOI: 10.1136/bmjnph-2023-000823ret
