Daily consumption of apple cider vinegar may help people to lose weight, a new clinical trial suggests - although some experts are warning the results could be "too good to be true".
Researchers from the Holy Spirit University of Kaslik in Lebanon found that small quantities of the vinegar each day over a 12-week period may aid weight management in people who are overweight or obese, according to the results of a small comparative clinical trial, which were published in the journal BMJ Nutrition, Prevention & Health.
Over three months, daily consumption of apple cider vinegar was associated with decreases in body weight, body mass index (BMI) and in levels of blood glucose, triglycerides, and cholesterol, leading the researchers to suggest it may be a useful supplementary treatment for obesity.
Apple cider vinegar is made with crushed fermented apples, yeast and sugar and is commonly used as an ingredient in salad dressings, pickles and marinades. For decades, people have also touted its supposed benefits as a home remedy.
In recent years, apple cider vinegar has become increasingly popular as a "weight loss remedy", the researchers said. To rest its purported benefits, they studied 120 young people (46 men and 74 women aged 12 to 25 with an average age of 17) who were overweight or obese, with a BMI of between 27 and 34.
Each participant was randomly assigned to one of four groups. Those in the first three were asked to drink apple cider vinegar once per day in quantities of 5, 10 or 15ml respectively (containing 5 percent acetic acid diluted in 250ml of water) for a period of 12 weeks, first thing in the morning and before food. Those in the fourth group were instead given a placebo liquid.
The timing was chosen to avoid the potential influence of other food and drink on appetite and satiety.
Participants were also tasked with recording what they ate in a 'diet diary' and providing information on their physical activity: these diary entries and physical activity records scarcely differed between the groups throughout the study. Subjects were asked not to alter their diet or exercise patterns over the 12-week period.
Compared with those given the placebo, the participants who were tasked with drinking the highest 'dose' of 15ml experienced the most significant decreases after 12 weeks.
On average, those who drank apple cider vinegar once daily during that period lost 6-8kg in weight and reduced their BMI by 2.7-3 points, depending on the dose.
At daily quantities of 5ml, the average weight fell from 79kg to 74kg. At 10ml this reduced from 79kg to 72kg, and at 15ml, the average weight dropped from 77kg to just over 70kg.
Similarly, BMIs fell from nearly 31 to nearly 29, from just over 30 to just over 27, and from 30 to just over 27 respectively.
The decreases in weight and BMI were much smaller among those in the placebo group over the same period: from just over 79kg to just under in weight, and from 30.7 to 30.6 BMI.
All three different quantities of apple cider vinegar were also associated with significant reductions in waist and hip measurements and body fat ratio compared with the placebo. These reductions were irrespective of dose, suggesting the effect didn't depend on the quantity, the researchers said.
Consumption of apple cider was also linked to a reduction in serum glucose, triglycerides and cholesterol, although these did seem to depend on the size of the dose, with the largest decreases recorded among those taking 15ml per day.
However, the researchers have acknowledged that due to the small size of the study sample, the generalisability of the findings is potentially limited. They also noted that a period of 12 weeks isn't long enough to gauge the possible long-term side effects of apple cider vinegar.
"These results suggest that apple cider might have potential benefits in improving metabolic parameters related to obesity and metabolic disorders in obese individuals," the researchers said.
"The results might contribute to evidence-based recommendations for the use of [apple cider vinegar] as a dietary intervention in the management of obesity.
"The study could stimulate further research in the field, prompting scientists to explore the underlying mechanisms and conduct similar studies in other populations."
Commenting on the findings, Professor Helen Truby - a Professorial Research Fellow (Nutrition and Dietetics) at the University of Queensland - said the weight loss among the apple cider vinegar drinkers was "remarkable".
"Although this study design has the ability to prove cause and effect there are some substantial problems in this study, which would make the conclusions drawn questionable," she noted.
She pointed out that the subjects may have been on a weight loss journey before they began taking the vinegar, and that as diet and activity were self-reported, researchers can't be sure the weight loss was not due to lifestyle changes or possibly weight loss medications.
"The results reported here are remarkable but would need to be reproduced in a more rigorously controlled environment before any confidence could be placed in their conclusions," she said.
"It would be wonderful if a teaspoon of apple cider vinegar caused substantial weight loss, but with the complexity of obesity and its management that we grapple with, sometimes if something seems too good to be true - it often is."
