Drinking apple vinegar before meals may reduce fasting blood glucose in people with type 2 diabetes.

“Daily consumption of this juice (20 ml/day) may decrease glycaemic indices, specifically FBS [fasting blood sugar], and may increase the total antioxidant capacity”, the researchers wrote.

The study “The effect of apple vinegar consumption on glycaemic indices, blood pressure, oxidative stress, and homocysteine in patients with type 2 diabetes and dyslipidaemia: A randomised controlled clinical trial” was published in Clinical Nutrition ESPEN.

The number of people with diabetes has been increasing between 1980 and 2021 from 108 million to 537 million, and its number will rise to 643 million people by 2030. Type 2 diabetes is the most common type of diabetes. It occurs because the body does not produce enough insulin, the cells stop responding to insulin or both.

People with type 2 diabetes risk developing complications such as eye disorders, kidney failure, heart disease and nerve damage if they do not maintain their blood sugar within target ranges. The American Diabetes Association recommends a target range of 80-130 mg/dL (4.4-7.2 mmol) before meals and less than 180 mg/dL (10.0 mmol) two hours after meals.

Eating a healthy, balanced diet rich in unprocessed grains, lean meats, fruits, vegetables, nuts, and seeds is essential for controlling blood glucose, blood pressure and fats. Whole foods, especially fruits and vegetables, are sources of chemicals called antioxidants that reduce oxidative stress and protect against diabetes and heart disease. Of note, oxidative stress occurs when there is an imbalance of protective antioxidants and damaging free radicals.

Researchers test if apple vinegar before meals could help reduce blood glucose

Apple vinegar is made by fermenting apples. It is used worldwide to flavour and preserve foods. Apple vinegar is rich in acetic acid and several antioxidant compounds, including polyphenols and flavonoids, known to reduce inflammation, oxidative stress and blood pressure and improve blood glucose and insulin responses.

“Since the number of human studies to assess the effect of apple vinegar are restricted, we aim to determine the effects of apple vinegar, as a rich source of acetic acids and polyphenols, on human glucose regulation, oxidative stress, and blood pressure by a parallel randomised clinical trial in patients with type 2 diabetes and dyslipidaemia [imbalanced blood fats]”, the researchers wrote.

In the study, participants in the treatment group were asked to drink diluted apple vinegar (10ml in a glass of water) before lunch and dinner for eight weeks but maintain their regular diet and physical activity.

The analysis included data on 62 people with type 2 diabetes: 32 were given apple vinegar, and 30 were in the control group. The mean age of the participants in the treatment group was 49 years, and 52 years in the control group. In both groups, around 67% of the participants were female.

To assess blood glucose control, the scientists measured fasting blood sugar, insulin resistance and beta (insulin-producing) cell function. They also measured DPPH (a marker of antioxidant capacity), MDA (a marker of oxidative stress), homocysteine (a marker of heart disease) and blood pressure. These metrics were evaluated at the beginning and end of the study.

Apple vinegar improves fasting blood glucose, reduces oxidative stress

Apple vinegar lowered fasting blood glucose by 10 mg/dl, reduced insulin levels and insulin resistance and improved the functioning of the insulin-producing cells. Apple vinegar also improved antioxidant status; that is, it increased the levels of antioxidants in patients and minimised the production of damaging free radicals. “This result confirms the antioxidant ability of the mentioned juice, hence, consuming apple vinegar may lead to a reduction in oxidative damage,” the scientists wrote.

Of note, apple vinegar did not change homocysteine or blood pressure levels. This result was in contrast to an epidemiological study of 2573 participants and an animal study showing that apple vinegar can improve blood pressure.

The scientists highlighted limitations to their study, including the lack of blinding of participants and personnel and not measuring the polyphenol content of apple vinegar.

“This trial provided some evidences that apple vinegar consumption may cause beneficial effects on glycaemic indices and oxidative stress in individuals with diabetes and dyslipidaemia”, the researchers concluded.

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