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Quick answer
Apple cider vinegar (ACV) is a sour, acidic liquid made by fermenting apple juice. Small studies suggest that taking a little vinegar with a carbohydrate-rich meal may slightly reduce the rise in blood sugar afterwards. Evidence that it helps with weight loss is weak, and claims that it detoxifies the body, cures acid reflux or balances the body's pH are not supported.
The bigger issue is safety. ACV is acidic enough to erode tooth enamel and, if taken undiluted or as tablets, to injure the throat. If you choose to use it, dilute it well and protect your teeth.
What is in apple cider vinegar
ACV is mostly water and acetic acid (typically 4 to 6%), with small amounts of other acids, a little potassium and trace polyphenols. Unfiltered ACV contains "the mother", a cloudy mix of yeast and bacteria. It is sometimes marketed as a probiotic, but there is no good evidence it offers meaningful health benefits.
What the research says
Blood sugar
This is the most studied area. Small trials, mostly lasting hours to a few weeks, have found that vinegar taken just before or with a high-carbohydrate meal can reduce the post-meal rise in blood glucose and insulin. Acetic acid appears to slow stomach emptying and may improve how muscles take up glucose.
The effect is modest, studies are small, and long-term effects on HbA1c (a measure of average blood sugar over months) are uncertain. Vinegar is not a treatment for diabetes and must not replace prescribed medicines.
Weight loss
The most cited study is a 12-week Japanese trial in which people who drank vinegar daily lost about 1 to 2 kg more than those on placebo. A few other small studies suggest similar small effects, possibly because vinegar makes people feel slightly fuller or a little queasy. The evidence is weak, and any effect is small compared with changes in diet and activity.
Cholesterol and blood pressure
Some small trials report slight improvements in cholesterol or triglycerides, but results are inconsistent and many studies have methodological problems.
Myths without evidence
- "Detox": your liver and kidneys clear waste products; vinegar does not help them do this.
- "Alkalising": vinegar does not change your blood pH, which the body keeps in a tight range.
- Acid reflux: there is no good evidence ACV helps reflux, and its acidity may make symptoms worse.
- Skin and hair: applying undiluted ACV to skin can cause chemical burns. It is not a treatment for warts, moles or skin infections.
How people use it
If you want to try ACV, the safer way is:
- Dilute it. Use 1 to 2 teaspoons (5 to 10 ml), up to 1 tablespoon (15 ml), in a large glass (about 250 ml) of water.
- Take it with a meal, not on an empty stomach.
- Use a straw to reduce contact with teeth, and rinse your mouth with plain water afterwards.
- Don't brush straight away. Acid softens enamel for a while; wait at least 30 to 60 minutes before brushing.
- Use it in food. Salad dressings and marinades are an easy way to include vinegar with meals.
Avoid ACV tablets and gummies. Tablets have caused throat injuries when they got stuck, the amount of acetic acid varies widely, and gummies add sugar.
Possible side effects and interactions
- Tooth erosion. Acetic acid can dissolve enamel, leading to sensitivity, discolouration and a higher risk of decay.
- Throat and stomach irritation. Undiluted vinegar can burn the throat and oesophagus and worsen indigestion.
- Delayed stomach emptying. Helpful for blood sugar in theory, but a problem for people with gastroparesis, a condition common in long-standing diabetes.
- Low potassium. There is a case report of very low potassium and bone loss after years of drinking large amounts.
- Medicine interactions. ACV may add to the effects of insulin and other diabetes medicines (risk of low blood sugar), and may worsen low potassium caused by some diuretics or digoxin.
Who should avoid it
- People with gastroparesis, reflux or stomach ulcers
- People with sensitive teeth or enamel erosion
- Anyone taking insulin, sulfonylureas, diuretics or digoxin, unless their doctor agrees
- People with kidney disease
- Children
When to see a doctor
See a doctor if:
- You are trying to manage blood sugar, weight, cholesterol or blood pressure. These conditions deserve proper assessment and proven treatment.
- You have symptoms of high blood sugar: being very thirsty, passing a lot of urine, tiredness, blurred vision or unexplained weight loss
- You have pain when swallowing or chest pain after taking vinegar or tablets
- You have persistent heartburn, difficulty swallowing or vomiting
- You develop tooth sensitivity or notice your teeth looking more yellow or translucent at the edges; see your dentist
Frequently asked questions
When is the best time to take apple cider vinegar?
In studies on blood sugar, vinegar was taken just before or with a carbohydrate-containing meal. Taking it on an empty stomach first thing in the morning is more likely to cause irritation.
Does apple cider vinegar burn belly fat?
No. There is no evidence that it targets belly fat. Any weight effect in studies was small.
Is ACV with "the mother" better?
There is no good evidence that unfiltered vinegar with the mother is healthier than filtered vinegar.
Can I drink apple cider vinegar every day?
Small, well-diluted amounts with meals are unlikely to cause harm for most healthy adults, as long as you protect your teeth. There is no strong reason to take it daily for health.
References
- Johnston CS, Kim CM, Buller AJ. Vinegar improves insulin sensitivity to a high-carbohydrate meal in subjects with insulin resistance or type 2 diabetes. Diabetes Care, 2004.
- Kondo T, et al. Vinegar intake reduces body weight, body fat mass, and serum triglyceride levels in obese Japanese subjects. Bioscience, Biotechnology, and Biochemistry, 2009.
- Hill LL, et al. Esophageal injury by apple cider vinegar tablets and subsequent evaluation of products. Journal of the American Dietetic Association, 2005.
- Zero DT, Lussi A. Erosion: chemical and biological factors of importance to the dental practitioner. International Dental Journal, 2005.