Apple cider vinegar (ACV) is currently the trending remedy on social media to reduce blood glucose in people with insulin resistance, prediabetes and type 2 diabetes. Is it all hype, or is it legit? Keep reading to learn more!

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Prediabetes occurs when the body becomes insulin resistant (does not respond to insulin effectively) or does not produce enough insulin, or both. It causes blood sugar levels to rise to unhealthy levels, and over time, it can progress to type 2 diabetes, leading to several health problems if mismanaged.

The American Diabetes Association recommends people with diabetes maintain their fasting or before-meal blood glucose at 70-130 mg/dL (4.4-7.2 mmol/L) and after-meal blood glucose at less than 180 mg/dL (10 mmol/L) two hours after meals.¹ Maintaining these target ranges, especially the after-meal glucose range, is crucial because studies have found a higher risk of complications, such as eye disorders, heart disease and kidney failure, in those with glucose levels above them.¹

Scientists have explored different ways to achieve these targets, including eating a low-glycaemic index diet, changing the order in which individuals eat their food, pairing carbohydrate-rich foods with proteins and vegetables and reducing overall carbohydrate intake.^2-5 They have also studied herbal and dietary supplements such as cinnamon, propolis, aloe vera, fenugreek, chromium, and ginger but have not found clear or clinically meaningful benefits with supplements.⁶ In contrast, ACV seems to reduce fasting and after-meal blood glucose and improves blood pressure, triglycerides and cholesterol. Before we explore the evidence, let’s cover some basics.

What is Apple Cider Vinegar?

Vinegar is an acidic, sour-tasting liquid made from fermentable carbohydrates, including grains, sorghum, potatoes, malt, fruits, honey, beer and whey.⁷

Apple cider vinegar (ACV) is made by fermenting apples. During fermentation, yeasts convert apple sugar to ethanol (alcohol), and bacteria convert ethanol to acetic acid.⁸ ACV is typically used as a flavouring, preservative and ingredient in salad dressing and condiments such as ketchup and mayonnaise. Fruit vinegars, including ACV, have been used to treat laryngitis, fever, swelling, stomach aches and rashes for over 3000 years. ACV’s medicinal properties are attributed to acetic acid and the antioxidant compounds it contains, including flavonoids and polyphenols.⁸

Nutritional Value of Apple Cider Vinegar

ACV is a low-calorie drink containing minerals and bioactive compounds that regulate metabolism (chemical processes in the body), provide energy, boost immunity and maintain the body’s balance of acidity and alkalinity.^8-10

Minerals

Minerals are essential for growth, development and normal functioning of the body.^8-10 The main minerals found in ACV include selenium, chromium, copper, magnesium, cobalt, zinc, sodium, potassium calcium, nickel and manganese.^8-10 Minerals such as potassium and zinc can generate alkaline substances, preventing blood from becoming too acidic.

Bioactive compounds

Oxidative stress plays a vital role in diabetes. It occurs when the body makes too many damaging chemicals called free radicals and lacks enough antioxidants to neutralise them. A common free radical in the body is hydrogen peroxide. When free radicals such as hydrogen peroxide enter the cell, they damage DNA, protective fats and proteins, causing extensive cell damage. Antioxidants can limit the effect of oxidative stress by suppressing free radical production. Hence, antioxidants play a significant role in managing chronic conditions like diabetes.

ACV contains many bioactive compounds, but organic acids and polyphenols are the main types.^9-10 These compounds have antioxidant properties that aid weight loss, lower blood pressure and glucose, improve lipid (blood fats) profile and limit oxidative stress.⁹ The primary organic acids and polyphenols in ACV are listed in the table below.

Care plans for prediabetes and type 2 diabetes involve managing weight, blood glucose, blood pressure and fats. Let’s look at the evidence of how ACV helps in human studies.

Evidence of Apple Cider Vinegar’s Benefit in Obesity, Prediabetes and Type 2 Diabetes

Khezri and colleagues investigated the effect of ACV and a low-calorie diet on body weight, body mass index (BMI), hip circumference, appetite and body fat in adults with overweight or obesity.¹² A total of 39 adults participated in the 12-week study; the participants split into an ACV or control group.  The ACV group ate a low-calorie diet and added 15mL of ACV to salads at lunch and dinner, while the control group ate a low-calorie diet and salads without ACV.  Both groups reduced weight, body fat, BMI and hip circumference, but the changes were more significant in the ACV group. The ACV group also had smaller appetites and improved blood fat profiles (lower triglycerides and increased HDL or ‘good’ cholesterol).

Kondo and colleagues investigated the effect of ACV on body weight, body fat and triglycerides in Japanese adults with obesity.¹³ The participants were split into three groups and given either a control drink, 15ml (low-dose) or 30ml (high-dose) of ACV after breakfast and dinner for 12 weeks while maintaining their usual diet and activity levels. Participants in the high-dose and low-dose groups lost 1.9kg and 1.2kg, respectively, while the control group maintained their weight. Triglycerides were also reduced by 0.47 mmol/l in the high-dose group and 0.31 mmol/l in the low-dose group. Overall, ACV significantly reduced body weight, body fat and triglyceride levels in the low and high-dose groups compared to the control group.

In a meta-analysis assessing the effects of ACV on blood pressure in people with obesity, type 2 diabetes and high cholesterol, 30ml of ACV daily for 7-12 weeks reduced systolic (top number) and diastolic (bottom number) blood pressure by up to 3.36 mmHg.¹⁴

A meta-analysis of nine studies found that up to 15ml of ACV daily could reduce total cholesterol and triglycerides in people with type 2 diabetes.¹⁵ However, it did not affect LDL or ‘bad’ cholesterol and HDL cholesterol. ACV also reduced fasting blood glucose by 7.97mg and HbA1c but did not affect insulin levels and insulin resistance.¹⁵ Another meta-analysis, including healthy individuals and people with diabetes, found that ACV could reduce after-meal blood glucose and insulin levels.¹⁶ Other meta-analyses have confirmed these findings and found that ACV significantly lowers HbA1c, fasting blood glucose and LDL cholesterol.¹⁷

How Apple Cider Vinegar Potentially Improves Blood Glucose

It is still unclear how ACV improves blood glucose, but scientists have proposed several pathways.

1 | Slows digestion:  Post-meal blood glucose results from how quickly glucose from a meal enters the bloodstream and how quickly the tissues and cells of the body use it up. Slower rates of digestion mean that glucose enters the bloodstream slowly and potentially reduces post-meal blood glucose. ACV slows digestion in patients with diabetes and gastroparesis.¹⁸

2 | Triggers the muscles to use glucose: Animal studies show that ACV encourages the muscles to take up glucose from the bloodstream and store it as glycogen, potentially reducing post-meal blood glucose.¹⁹

3 | Improves the functioning of insulin-producing cells: Animal studies show that ACV improves insulin sensitivity and increases insulin secretion.²⁰

4 | Stops the liver from producing excess glucose: The liver typically produces glucose at night, but this can increase fasting blood glucose in people with type 2 diabetes, known as the dawn phenomenon. In animal studies, ACV encourages the liver to store glucose as glycogen instead of releasing it into the bloodstream. It also enables the liver to burn fat, improving insulin sensitivity.²⁰  

Should You Take Apple Cider Vinegar?

Speaking to your doctor or healthcare team before taking ACV would be best.  Some patients have reported side effects from taking undiluted vinegar or pills containing acetic acid (the active ingredient in vinegar), such as throat burns, reflux, burping, flatulence or changes in bowel movement.²⁰ However, there are no adverse reports of moderate use, such as two tablespoons in salad dressings.

Summary

ACV contains several substances, especially acetic acid and polyphenols, that help lower blood glucose, blood pressure and cholesterol. Animal and human studies show that adding ACV to the diet in small amounts may benefit people with prediabetes and type 2 diabetes if used alongside a healthy, balanced diet. Larger human studies are needed to confirm these findings.

Try These Tips

• Make fresh, homemade salad dressings with vinegar.
• Add vinegared or pickled foods like pickled cucumbers or cabbage to your diet.

References

1. ElSayed, N.A., Aleppo, G., Aroda, V.R., Bannuru, R.R., Brown, F.M., Bruemmer, D., Collins, B.S., Hilliard, M.E., Isaacs, D., Johnson, E.L., Kahan, S., Khunti, K., Leon, J., Lyons, S.K., Perry, M.L., Prahalad, P., Pratley, R.E., Seley, J.J. Stanton, R.C., & Gabbay, R.A on behalf of the American Diabetes Association (2023). Glycaemic targets: standards of care in diabetes – 2023. Diabetes Care, 46(Supplement 1); S97-S110.
2. Liu, A.G., Most, M.M., Brashear, M.M., Johnson, W.D., Cefalu, W.T., & Greenway, F.L. (2012) Reducing the glycaemic index or carbohydrate content of mixed meals reduces postprandial glycaemia and insulinaemia over the entire day but does not affect satiety. Diabetes Care, 35(8): 1633-7.
3. Okami, Y., Tsunoda, H., Watanabe, J., & Kataoka, Y. (2022). Efficacy of a meal sequence in patients with type 2 diabetes: A systematic review and meta-analysis. BMJ Open Diabetes Research & Care, 10(1): e002534.
4. Oliveira, B. F., Chang, C. R., Oetsch, K., Falkenhain, K., Crampton, K., Stork, M., Hoonjan, M., Elliott, T., Francois, M. E., & Little, J. P. (2023). Impact of a Low-Carbohydrate Compared with Low-Fat Breakfast on Blood Glucose Control in Type 2 Diabetes: A Randomised Trial. The American Journal of Clinical Nutrition, 118(1), 209-217.
5. Manios, Y., Moschonis, G., Mavrogianni, C., Tsoutsoulopoulou, Kogkas, S., Lambrinou, C-P., & Efstathopoulou, E. (2017) Postprandial glucose and insulin levels in type 2 diabetes mellitus patients after consumption of ready-to-eat mixed meals. European Journal of Nutrition, 56: 1359-1367.
6. Hekmat-Ardakani, A., Morshed-Behbahani, B., Rahimi-Ardabili, H., Ayati, M.H., Namazi, N. (2022) The effects of dietary supplements and natural products targeting glucose levels: an overview. Critical Reviews in Food Science and Nutrition, 1-30.
7. Johnston, C.S., & Gaas, C.A. (2006) Vinegar: Medicinal uses and anti-glycaemic effect. Medscape General Medicine, 8(2): 61.
8. Chen, H., Chen, Y., Giudici, P., Chen, F. (2016) Vinegar functions on health: constituents, sources and formation mechanisms. Comprehensive Reviews in Food Science and Food Safety, 15(6): 1124-1138.
9. Xia, T., Zhang, B., Duan, w., Zhang, J., & Wang, M. (2019) Nutrients and bioactive components from vinegar: A fermented and functional food. Journal of Functional Foods, 64: 103681
10. Ho, C.W., Lazim, A.M., Fazry, S., Zki, UKHH, & Lim, S.J. (2017) Varieties, production, composition and health benefits of vinegars: a review. Food Chemistry, 221(15): 1621-1630.
11. U.S. Department of Agriculture. Vinegar, cider (2019). Available: https://fdc.nal.usda.gov/fdc-app.html#/food-details/173469/nutrients. Accessed: 28 August 2023.
12. Khezri, S.S., Saidpour, A., Hosseinzadeh, N., & Amiri, Z. (2018) Beneficial effects of apple cider vinegar on weight management, visceral adiposity index and lipid profile in overweight or obese subjects receiving restricted calorie diet: a randomised clinical trial. Journal of Functional Foods, 43: 95-102.
13. Kondo, T., Kishi, M., Fushmimi, T., Ugajin, S., & Kaga, T. (2009) Vinegar intake reduces body weight, body fat mass, and serum triglyceride levels in obese Japanese subjects. Biosciences, Biotechnology & Biochemistry, 8: 1837-1843.
14. Shahinfar, H., Amini, M. R., Payandeh, N., Torabynasab, K., Pourreza, S., & Jazayeri, S. (2022). Dose-dependent effect of vinegar on blood pressure: A GRADE-assessed systematic review and meta-analysis of randomised controlled trials. Complementary Therapies in Medicine, 71, 102887.
15. Hadi, A., Pourmasoumi, M., Najafgholizadeh, A., Clark, C.C.T., & Esmaillzadeh, A. (2021) The effect of apple cider vinegar on lipid profiles and glycemic parameters – a systematic review and meta-analysis of randomised clinical trials. BMC Complementary Medicine and Therapies, 21: 179.
16. Shishehbor, F., Mansoori, A., Shirani, F. (2016) Vinegar consumption can attenuate postprandial glucose and insulin responses; a systematic review and meta-analysis of clinical trials. Diabetes Research and Clinical Practice,
17. Cheng, L.J., Jiang, Y., Wu, V.X., & Wang, W. (2020) A systematic review and meta-analysis: Vinegar consumption on glycaemic control in adults with type 2 diabetes mellitus. Journal of Advanced Nursing, 76: 459-474.
18. Hlebowicz, J., Darwiche, G., Bjorgell, O, and Almer, L-O. (2007) Effect of apple cider vinegar on delayed gastric emptying in patients with type 1 diabetes mellitus: a pilot study. BMC Gastroenterology, 7: 46
19. Fushimi, T., Tayama, K., Fukaya, M., Kitakoshi, K., Nakai, N., Tsukamoto, Y., & Sato, Y. (2001) Acetic acid feeding enhances glycogen repletion in liver and skeletal muscles of rats. Journal of Nutrition, 131(7): 1973-7.
20. Petsiou, E.I., Mitrou, P.I., Raptis, S.A., & Dimitriadis, G.D. (2014) Effect and mechanisms of action of vinegar on glucose metabolism, lipid profile, and body weight. Nutrition in Clinical Care, 72(10): 651-661.

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