Study claiming weight-loss benefits of apple cider vinegar retracted

BMJ retracts widely cited study after review finds irregularities in data set

A study widely cited as evidence of apple cider vinegar’s weight-loss effects has been retracted, the BMJ publishing group announced.

The study, published last year in the journal BMJ Nutrition, Prevention & Health, suggested that consuming small quantities of apple cider vinegar daily could help overweight or obese people lose weight.

It garnered widespread attention and went on to be widely cited.

The study involved 120 people, aged 12 to 25, who were split into groups that either drank a placebo or 5 ml, 10 ml or 15 ml of apple cider vinegar each morning.

After three months, the study claimed, people who drank vinegar lost 5 to 7kg while those who drank the placebo lost less than 1kg of weight.

“These results suggest,” the research concluded, “that apple cider might have potential benefits in improving metabolic parameters related to obesity and metabolic disorders in obese individuals.”

The study, however, also drew criticism. “While the study addresses a very important issue and the methodology appears robust at first glance, some results seem statistically improbable and warrant clarification,” one group of researchers commented in the same journal.

Photo illustrating fermentation and acetation of cider vinegar in Normandy in France (AFP via Getty)

Following the criticism, the BMJ Group referred the study to statistical experts to evaluate its reliability, including attempts to replicate the results, and examine the authenticity of the underlying data supplied by the authors.

Independent researchers found it wasn’t possible to replicate the results. They also flagged irregularities in the study’s data set, concluding that data collected from the participants required further independent scrutiny.

Given these concerns about the quality of the study, the journal decided to retract it.

The study’s authors claimed the errors found during scrutiny were “honest mistakes” but agreed with the decision to retract it.

“Tempting though it’s 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,” Helen Macdonald, BMJ Group’s ethics and content integrity editor, explained the decision.

“Investigations are often complex. This one involved detailed scrutiny of data and correspondence with researchers, institutions, and other experts, for example,” Dr Macdonald added. “Reaching a sound and fair and final decision can therefore take several months.”