Does Apple Cider Vinegar Improve Gut Health?

No human trial has measured apple cider vinegar's effect on the bacteria in the gut. What the trials have measured is a smaller rise in blood glucose after a carbohydrate meal when the vinegar is taken with that meal, a standardised reduction of 0.60 across the pooled meal studies, and, over 12 weeks at 15 to 30 mL a day, lower weight, waist and triglycerides than placebo.^{1, 2} The digestion, bloating and reflux uses rest on long tradition and on how acetic acid behaves in the stomach, not on trials. This page sets out what apple cider vinegar is, what the trials measured, how much people take and how, and what too much of it does.

Apple cider vinegar has been used for centuries in cooking and home remedies, and many people now drink small, diluted amounts for digestion. The full trial record is on what are the benefits of apple cider vinegar?; this page is about the gut.

What is apple cider vinegar, and what has been measured?

Apple cider vinegar is apple juice fermented twice. Yeasts turn the sugar in the juice into alcohol, then acetic acid bacteria turn the alcohol into acetic acid, the compound that makes vinegar sour and the part the trials are about. A standard bottle is about 5% acetic acid, so 15 mL carries about 750 mg.²

In unfiltered, unpasteurised vinegar you will find "the mother": the cloudy strands left by the acetic acid bacteria that made the vinegar. It is often described as packed with enzymes and friendly bacteria, but no trial has compared vinegar with and without it.

What the human trials and laboratory studies have measured:

• Blood glucose after a meal: across the pooled meal studies, the glucose response was lower by a standardised 0.60 and the insulin response by 1.30 when vinegar was drunk with a carbohydrate meal.¹
• Fasting glucose, HbA1c and cholesterol: across nine trials of two weeks or more, fasting glucose was about 0.4 mmol/L lower, HbA1c about 0.5 percentage points lower and total cholesterol about 0.16 mmol/L lower. The fasting glucose effect came from trials over eight weeks, mostly in type 2 diabetes; in apparently healthy people fasting glucose appeared to rise rather than fall, and LDL and HDL did not change.³
• Weight: in one 12-week trial, 155 Japanese adults with obesity drank 15 or 30 mL of vinegar a day in a 500 mL drink, and body weight, waist, visceral fat area and triglycerides were lower than on placebo; the study was run by a vinegar maker.²
• Bacteria in the laboratory: in a 2018 dish study, apple cider vinegar stopped the growth of E. coli at a 1 in 50 dilution, Staphylococcus aureus at 1 in 25 and Candida albicans at 1 in 2: a result in a dish, not in a person.⁴

The immune and skin claims that circulate have not been tested in people.

Does apple cider vinegar restore gut health?

Not in any way that has been measured. The usual explanation is that poor gut health comes from too much "bad" bacteria and that acetic acid feeds the good or kills the bad. A PubMed search on 19 October 2026 found no human trial that measured apple cider vinegar's effect on the gut microbiome; the dish study above tested three microbes in culture, not a gut.⁴ What vinegar measurably does is slow stomach emptying: in ten people with type 1 diabetes and already slow emptying, 30 mL in water with a meal cut the emptying rate from 27% to 17% over 90 minutes.⁵ That slowing is the mechanism behind the glucose effect, and why anyone with gastroparesis should ask their diabetes team before using vinegar daily.

Three things people read as signs of poor gut health, and what the NHS says:

1. Poor sleep

Reflux and an unsettled stomach disturb sleep. The NHS notes that reflux is often worse after eating and when lying down, and advises not eating within three or four hours of bed and raising the head of the bed by 10 to 20 cm.⁶ Vinegar has no trial against reflux.

2. Upset stomach and bloating

The NHS says the most common reason for bloating is gas in the gut, from some foods and drinks (some vegetables, fizzy drinks) or from swallowing air, and that constipation, a food intolerance, coeliac disease and irritable bowel syndrome can also be behind it. See a GP if you are bloated regularly or it does not go away.⁷

3. Craving sugary and processed foods

A craving is not a reading of your gut bacteria. The NHS advice for a bloated or unsettled gut is to go easy on processed, sugary, spicy and fatty foods, to drink plenty of water and, if constipated, to eat foods high in soluble fibre such as oats or linseed.⁷ Seven things you can do to improve gut health has the diet changes that have been measured.

How much apple cider vinegar should I drink for gut health?

The trials used 15 to 30 mL a day, always diluted, and the glucose studies gave it with the carbohydrate meal.^{1, 2} The popular routine of 30 mL in water first thing on an empty stomach has no trial behind it and puts the most acid on your teeth; a large glass of water with a meal is where the evidence comes from. A 2020 systematic review of 13 human studies judged the risk of side effects at recommended amounts, taken in the recommended way, inconsiderable.⁸ Neat, often or in large amounts, the problems are physical:

• Teeth: vinegar has a pH around 3 and in laboratory tests dissolved measurable mineral from human enamel within hours; dilute it, rinse with water and wait 30 minutes before brushing.⁹
• Throat: undiluted vinegar can irritate the throat, and the one published injury to the oesophagus came from a tablet lodged there.¹⁰
• Stomach: too much acid on an empty stomach can leave it sore; the NHS lists acidic foods such as salad dressings and citrus among the common heartburn triggers, so if you have reflux or a stomach ulcer, take advice first.¹¹
• Potassium: one woman who drank large amounts daily for years developed low potassium and osteoporosis: a case report about excess, not a tablespoon.¹²

If you take insulin or glucose-lowering tablets, tell your diabetes team before taking vinegar daily, because its post-meal effect adds to theirs. If the liquid is hard to take, a capsule or gummy is a measured dose without acid on the teeth; what do apple cider vinegar gummies do? describes the format.

Frequently asked questions

How do you use apple cider vinegar for gut health?

Diluted, with food. Three ways people take it: a warm drink of hot water, a teaspoon of lemon juice and one or two teaspoons of vinegar, with a little honey if it is too sharp; a salad dressing of olive oil, vinegar and lemon juice; or a diluted shot in a small glass of water before a meal. The trials used 15 to 30 mL a day in a large drink with a meal.^{1, 2}

Does apple cider vinegar help with bloating or reflux?

No trial has tested it for either. Vinegar slows stomach emptying, and the NHS lists acidic foods and dressings among the things that can trigger heartburn, so if reflux is your problem, follow the NHS advice (smaller meals, nothing within three or four hours of bed, a pharmacist's antacid or alginate) and see a GP if it keeps happening.^{5, 6, 11}

Does the mother in apple cider vinegar contain probiotics?

It contains the acetic acid bacteria that made the vinegar. No trial has compared vinegar with and without the mother, and those bacteria have not been tested as live cultures in people. Live cultures with a trial record come from live yoghurt, kefir and raw fermented vegetables; foods high in Lactobacillus has the list.

Is cider vinegar good for your gut?

It is a food with a measured effect on the rise in blood glucose after a meal and a modest 12-week effect on weight, and no measured effect on gut bacteria either way.^{1, 2} Diluted and with food, side effects were judged inconsiderable; neat, often or in large amounts, it erodes enamel, irritates the throat and, at the extreme, lowers potassium.^{8, 9, 10, 12}

Sources checked on 19 October 2026.

Sources

1. Shishehbor F, et al. Vinegar consumption can attenuate postprandial glucose and insulin responses; a systematic review and meta-analysis of clinical trials. Diabetes Research and Clinical Practice, 2017. Pooled analysis of controlled meal studies; standardised mean difference -0.60 glucose, -1.30 insulin. PubMed 28292654.
2. 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. Double-blind randomised trial, 155 adults, 15 or 30 mL a day (750 or 1,500 mg acetic acid), 12 weeks; authors employed by a vinegar maker. PubMed 19661687.
3. Hadi A, et al. The effect of apple cider vinegar on lipid profiles and glycemic parameters: a systematic review and meta-analysis of randomized clinical trials. BMC Complementary Medicine and Therapies, 2021. Pooled analysis of 9 trials of 2 weeks or more; total cholesterol -6.06 mg/dL, fasting glucose -7.97 mg/dL, HbA1c -0.50. PubMed 34187442.
4. Yagnik D, et al. Antimicrobial activity of apple cider vinegar against Escherichia coli, Staphylococcus aureus and Candida albicans. Scientific Reports, 2018. Laboratory culture study; growth inhibited at dilutions of 1/50, 1/25 and 1/2; no competing interests declared. PubMed 29379012.
5. Hlebowicz J, et al. Effect of apple cider vinegar on delayed gastric emptying in patients with type 1 diabetes mellitus: a pilot study. BMC Gastroenterology, 2007. Blinded crossover study, 10 people with type 1 diabetes and gastroparesis; median emptying rate 27% without and 17% with vinegar. PubMed 18093343.
6. NHS. Heartburn and acid reflux. Page last reviewed 20 November 2023. nhs.uk/conditions/heartburn-and-acid-reflux.
7. NHS. Bloating. Page last reviewed 21 January 2026. nhs.uk/symptoms/bloating.
8. Launholt TL, et al. Safety and side effects of apple vinegar intake and its effect on metabolic parameters and body weight: a systematic review. European Journal of Nutrition, 2020. Systematic review, 13 human and 12 animal studies. PubMed 32170375.
9. Willershausen I, et al. In vitro study on dental erosion caused by different vinegar varieties using an electron microprobe. Clinical Laboratory, 2014. Laboratory study, human enamel samples, 5 vinegars (pH 2.7 to 3.95), up to 8 hours. PubMed 24839821.
10. Hill LL, et al. Esophageal injury by apple cider vinegar tablets and subsequent evaluation of products. Journal of the American Dietetic Association, 2005. Case report and analysis of 8 tablet products. PubMed 15983536.
11. NHS. Good foods to help your digestion. Page last reviewed 5 January 2023. nhs.uk/live-well/eat-well/digestive-health/good-foods-to-help-your-digestion.
12. Lhotta K, et al. Hypokalemia, hyperreninemia and osteoporosis in a patient ingesting large amounts of cider vinegar. Nephron, 1998. Single case report. PubMed 9736833.

General information, not medical advice. Apple cider vinegar is a food, not a treatment: if you take insulin or glucose-lowering tablets, have gastroparesis, reflux or a stomach ulcer, or are pregnant, ask your GP, diabetes team or pharmacist before taking it daily.