Study supporting apple cider vinegar for weight loss retracted

Key takeaways:

• BMJ Group retracted a small study supporting apple cider vinegar for weight loss due to quality concerns.
• An expert told Healio that existing evidence on apple cider vinegar “is limited and inconsistent.”

BMJ Group announced its retraction of an analysis indicating that small daily amounts of apple cider vinegar may help produce weight loss in people with unhealthy weight.

The randomized clinical trial, published in BMJ Nutrition, Prevention & Health in March 2024, showed that adults with overweight or obesity who were assigned 5 mL, 10 mL or 15 mL of apple cider vinegar daily had reduced weight and BMI over a 12-week period vs. placebo.

“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,” Helen Macdonald, MSc, publication ethics and content integrity editor at BMJ Group, said in a press release. “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.”

Quality concerns led to retraction

According to the release, there were several concerns regarding the study, which included its:

• “implausible” statistical values;
• approach to data analysis;
• insufficient reporting methods;
• reliability of raw data; and
• lack of prospective trial registration, “which breaches BMJ Group’s editorial policy.”

These concerns were raised in critiques of the study and in letters to the journal.

“Inappropriate statistical methods were used, including multiple independent t tests, which inflated the risk for type I error and did not account for the study design,” Fatima Cody Stanford, MD, MPH, MPA, MBA, MACP, FAAP, FAHA, FAMWA, FTOS, an obesity medicine physician scientist at Massachusetts General Hospital and Harvard Medical School, told Healio.

Stanford said the lack of trial registration “raises concerns about selective reporting and transparency” while the inadequate reporting “makes it difficult to assess the validity and reproducibility of the findings.”

Statistical experts were unable to replicate the trial’s results. They also identified analytic errors and concluded data collected from each study participant “would require further independent scrutiny,” the release said.

According to BMJ Group, the study authors said the errors were “honest mistakes” but agreed with the decision to retract the data.

Martin Kohlmeier, MD, PhD, editor in chief of BMJ Nutrition Prevention & Health, said in the release that the choice to publish the study despite the lack of trial registration “in hindsight … 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,” he said. “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.”

‘Limited’ evidence beyond retracted data

According to Stanford, current evidence on the use of apple cider vinegar for weight loss beyond the retracted trial “is limited and inconsistent.”

“Some small studies have suggested modest weight loss effects, potentially due to delayed gastric emptying and increased satiety,” she said. “However, these studies have significant limitations, including small sample sizes, short durations and methodological weaknesses.”

There is no strong, high-quality evidence from large randomized controlled trials supporting apple cider vinegar as a weight loss intervention, Stanford said.

She further highlighted multiple risks tied to apple cider vinegar consumption, which include “gastrointestinal irritation, dental erosion and interactions with medications, particularly in patients with diabetes or those taking potassium-lowering drugs.”

Clinical implications

Stanford told Healio that physicians should “emphasize evidence-based weight management strategies, including lifestyle modifications, pharmacotherapy, and metabolic and bariatric surgery, as appropriate,” and educate patients on the lack of strong evidence on apple cider vinegar and its possible risks.

She also recommended engaging in shared decision-making with patients, “discussing the risks and benefits of various weight management options, and tailoring recommendations to individual patient needs and preferences.”

For more information:

Fatima Cody Stanford, MD, MPH, MPA, MBA, MACP, FAAP, FAHA, FAMWA, FTOS, can be reached at primarycare@healio.com.

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