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My medical training has made me a skeptic. When one learns of the limitations of diligently-studied therapeutics, one understandably is cautious about therapies that lack or have been minimally investigated. Metformin is a wonder drug for diabetes; hence, it is often the first therapy recommended to patients with newly-diagnosed diabetes. It does not replace lifestyle factors, such as exercising and eating a predominantly wholesome diet.
Supplements are marketed as magic, readily-available without prescription life changers. While they come with bulletins on the bottle that they are not indicated to treat disease, it can be easy to place weight on claims that a substance “helps balance blood sugars” or “could help with weight loss.” One may even be inclined to solely rely on supplements given that they must be safer than prescription medications because no prescription means it has to be safe, right?
The reality of supplements is that their therapeutic potential is typically meagre at best. They also can come with adverse effects that rival or exceed prescription medications. Today, I will discuss apple cider vinegar’s impact on weight loss with the critical lens required to sift through the often overzealous marketing.
Apple Cider Vinegar and Weight Loss
Given the prevalence of obesity and all of us knowing that excess weight (i.e. BMI > 25) is not the best, marketing for weight loss is an attractive strategy. Heck, it gets attention, as my Medium readers can attest seeing how many articles on this platform have something to do with the topic. But what does the data show?
I identified two clinical trials investigating the relationship, one with 175 obese Japanese individuals and another including 39 overweight/obese Iranian individuals. The investigators were affiliated with the Mizkan Group Corporation, a company that sells food products such as vinegar. This is a major red flag for trusting the study’s results, given how such an affiliation could bias what is reported.
The Iranian study readily disclosed its funding source and lack of conflicts of interest, making it seem like a reasonably trustworthy study. While they did not blind their participants in the placebo group, i.e. individuals who did not receive the apple cider vinegar, contrary to the Japanese research, the randomized study design affords credibility to their findings.
Onto the results. The Japanese study found that those individuals who consumed apple cider vinegar had a slightly lower BMI than those who did not. The placebo group started at an average 26.9 finishing at 27.1. Those individuals that took “high dose” vinegar, i.e. 30 mL of vinegar at meals, finished with an average BMI of 26.3 at week 12 of the study compared to an average BMI of 27.0 at week zero. Their BMI rebounded to 26.8 four weeks after the termination of the study. While the authors found a “statistically significant” decrease of the BMI at the end of the study, a BMI change of 0.7 is not a lot, and one will be bound to get a “significant” result just by nature of having a large number of individuals in the study when one considers the math.
A rebounding BMI back to roughly where individuals started is also concerning. The authors were unclear on their study protocol in the four weeks post-study. The protocol suggested that participants were kept from consuming non-study vinegar products during the study, but it is unclear if this was followed in the four weeks afterwards. This makes it hard to place the rebound BMI gain in perspective. My overall opinion is that while apple cider vinegar may facilitate weight loss in overweight/obese individuals, the effect is small if it exists at all. The effect seems limited to when individuals are consuming the product. Thus, it does not appear to translate to permanent weight loss. Therefore, this study does not give a lot of confidence that apple cider vinegar will magically make you thin.
What about the Iranian study? First off, this is a smaller study, making the results a bit less trustworthy. The study was set up similarly to the Japanese research, where individuals were tracked over 12 weeks, except individuals were not followed up four weeks afterwards. The study had similar findings with a statistically significant decrease in BMI over the twelve weeks for those who received the apple cider vinegar. The BMI in the vinegar group went from an average of 32.0 to 30.3 compared to the no-vinegar group going from 32.2 to 31.4.
This change is more pronounced than in the Japanese study, which could be due to the population, that apple cider vinegar offers a more significant effect for individuals with a higher BMI, or there is something special about the apple cider vinegar used in the study.
Similar to the Japanese study, there are issues with the statistics. The confidence intervals, which provide a measure of how sure we can be of these results, are a major point of concern. The confidence intervals are very broad, suggesting we should be more skeptical of the results.
Supplements have become mainstream, for better or worse. Many come with tempered claims that, regardless, make them sound like a great addition to our lives. As we observed in these two papers, the therapies tend to have minimal if any effect. While BMI was observed to decrease in these studies, it did not change much when comparing the groups who received vinegar with those who did not. The statistics did not strike me as particularly convincing. As is so often iterated, a healthy diet and exercise are typically the best treatment for extra weight. Magic pills are unfortunately not based on enough reality to make a difference for the average consumer.