Apple cider vinegar (ACV) is apple juice that has been fermented twice, and acetic acid is its main active ingredient, according to Cleveland Clinic. In human trials lasting 4 to 12 weeks, daily ACV was linked to small improvements in fasting blood sugar, body weight and total cholesterol. The trials were small and varied a lot, and none shows ACV is a quick fix or a substitute for treatment. Undiluted, it can damage teeth and irritate the throat, and it can interact with some medicines.
Quick facts
| Item | What the research shows |
|---|---|
| Forms studied | Mostly liquid ACV, often diluted in water. One trial used an effervescent tablet. Pills, powders and gummies have been studied far less. |
| Doses used in trials | 5 to 30 mL a day in the weight review; 15 mL a day up to one outlier of 770 mL a day in the blood sugar and cholesterol review |
| Typical study length | 4 to 12 weeks (30 to 90 days) |
| Main studied uses | Body weight, BMI and waist size; fasting blood sugar and HbA1c; total cholesterol and triglycerides; blood pressure (studied for vinegar in general) |
| Who was studied | Mostly adults with overweight, obesity or type 2 diabetes |
| Strength of evidence | Weak to moderate and mixed. Results differ a lot between trials. |
What does the human evidence show?
Reviews that pool several trials (see our guide to meta-analyses and systematic reviews) give the best overview. Strongest evidence comes first below.
Blood sugar
A 2021 meta-analysis of randomized trials pooled 9 studies (10 study arms, 686 adults, mean age 49.5) lasting 30 to 90 days. ACV was linked to lower fasting plasma glucose (about 8 mg/dL lower) and a 0.50 drop in HbA1c. It showed no significant effect on fasting insulin or insulin resistance. The HbA1c result stopped being significant when one study was removed, and also when high-risk-of-bias studies were excluded. Results varied a lot between trials, and the authors say the findings should be interpreted with caution.
A 2020 review of vinegar in type 2 diabetes found 6 studies with 317 people and reported better fasting glucose and HbA1c. Vinegar content varied across those studies (they were not all ACV) and the samples were small, so the authors advise caution in applying the results to larger populations.
One 12-week open-label trial in 126 adults with newly diagnosed type 2 diabetes, described in a 2025 weight review, compared metformin (750 mg) alone with metformin plus 2 tablespoons of ACV a day. Fasting glucose and HbA1c fell significantly more in the group that also took ACV. Because it was open-label, participants knew what they were taking, and the study tested ACV added to a drug, not in place of it. Cleveland Clinic’s dietitian says ACV “might lower your glucose a little, but not enough” to replace a healthy diet and exercise.
Body weight and BMI
A 2025 meta-analysis pooled 10 randomized trials (789 participants) of adults taking ACV for at least 4 weeks. Daily ACV was linked to lower body weight, BMI and waist circumference. Weight and BMI results held after high-risk-of-bias studies were excluded. The authors call ACV a possible add-on for short-term weight management in adults with excess weight or type 2 diabetes.
Limits matter here. The studies disagreed a lot with each other (heterogeneity of 61% to 83%). The full paper notes uneven funnel plots, which can mean small or unpublished studies are skewing the picture. Trials ran only 4 to 12 weeks. The paper also says an earlier meta-analysis covering studies up to 2022 found no significant BMI effect. The authors turn their pooled result into an estimated average loss of about 7.4 kg, but that is a conversion across very different trials. A single 12-week trial described by WebMD found a few extra pounds lost with ACV on a reduced-calorie diet. That trial followed 39 people, was not blinded and did not record food or exercise. Cleveland Clinic’s source says there is no concrete evidence of long-term appetite suppression.
Belly fat and waist size
In the same 2025 meta-analysis, waist circumference fell overall. Waist-to-hip ratio did not change significantly. Fat mass was reported in only one study, so it could not be judged. In subgroups, waist size fell significantly only in people with type 2 diabetes, not in people with overweight or obesity alone. The authors say the effect may show more in overall body mass than in where fat sits. WebMD notes that the 39-person trial lowered a visceral adiposity index (an estimate of deep belly fat), but its small size and other flaws mean it does not prove ACV fights belly fat. In short, these trials do not show that ACV specifically targets belly fat.
Cholesterol and triglycerides
The 2021 meta-analysis found total cholesterol about 6 mg/dL lower with ACV. LDL and HDL cholesterol showed no significant overall change. Triglycerides fell on average, but the result was borderline (p = 0.05) and shifted depending on which trial was removed. The drop in total cholesterol and triglycerides was clearer in people with type 2 diabetes, in trials longer than 8 weeks, and in trials using 15 mL a day or less. The review’s own analysis found no consistent link between dose and outcome. The 2020 vinegar review also reported lower total cholesterol and LDL in people with type 2 diabetes.
Blood pressure
A 2022 dose-response meta-analysis covered vinegar in general, not only ACV. Each 30 mL a day was linked to about 3 mmHg lower systolic and diastolic pressure, and the certainty of evidence was rated low. Cleveland Clinic’s source says ACV can interact with certain blood pressure medicines, so this is not a reason to change treatment on your own.
Acid reflux, immunity, gut health and other claims
Cleveland Clinic’s source says there is no real science behind ACV for heartburn, and WebMD says no research proves it works for reflux. WebMD also says research has not shown that the cloudy sediment called “the mother” offers any particular benefit. Claims about probiotics, immunity and cell protection come from explanations of what ACV contains, not from outcome trials in the pages cited here. A West Virginia University Extension page says none of ACV’s health claims is supported by good evidence, though it notes studies reporting a lower glucose response after meals.
What happens if you take it every day, and when should you take it?
In the trials, daily ACV for up to 12 weeks was linked to small average changes in glucose, weight and cholesterol, and some people got stomach burning or could not tolerate it. The reviews found no trial that compares morning with night. WebMD says there is not much research on the best time, and that people prone to heartburn should avoid taking it within an hour of bedtime. A weight trial WebMD describes used about 2 tablespoons a day, one before lunch and one before dinner. The shortest trials in the weight review lasted 4 weeks, so a result in 3 days or 1 week has not been tested there. No drink is shown by these studies to burn belly fat fastest.
Doses used in studies
These are amounts researchers used, not recommendations. Cleveland Clinic says there is no standard dosage, and WebMD says there are no official dosage suggestions.
| Source | Amount used or reported |
|---|---|
| 2025 weight meta-analysis | 5 to 30 mL a day, liquid or effervescent tablet (about 14 mL of ACV in one trial), 4 to 12 weeks. A significant weight effect appeared only in the 30 mL a day subgroup. |
| 2021 sugar and cholesterol meta-analysis | 15 mL a day up to 770 mL a day in one trial, 30 to 90 days. Cholesterol effects were clearer at 15 mL a day or less, and the review found no consistent dose link. |
| 2022 blood pressure meta-analysis | Effects estimated per 30 mL a day of vinegar, across vinegars generally |
| Single trials described by WebMD | About 2 tablespoons a day (before lunch and dinner) in the weight trial; about 1 1/2 tablespoons after a meal in blood sugar and cholesterol work |
| Trial settings | Several trials diluted ACV in 100 to 250 mL of water; controls got water, a taste-matched drink, diet advice or no treatment |
Is it safe? Side effects and interactions
| Issue | What the official and health-system pages say |
|---|---|
| Teeth | Acidity can erode enamel, which does not grow back (Cleveland Clinic). Undiluted ACV can break down enamel; WebMD suggests a straw. |
| Throat and esophagus | Straight ACV can burn or irritate the esophagus. Cleveland Clinic suggests diluting a tablespoon in a mug of warm water. |
| Nausea, indigestion | Some people feel sick or vomit. Both Cleveland Clinic and WebMD say to stop if that happens. WebMD says not to take it on an empty stomach. |
| Low potassium | Can worsen low potassium (hypokalemia). The West Virginia University page also links too much ACV to lower potassium and calcium. |
| Medicine interactions | Insulin, diuretics (water pills), laxatives and certain blood pressure medicines, per Cleveland Clinic. WebMD lists diuretics, laxatives and insulin. West Virginia University adds diabetes and heart disease medicines. |
| Slow stomach emptying | ACV slows gastric emptying, which matters for gastroparesis (Cleveland Clinic) |
| Kidney disease | WebMD says to avoid overusing it because kidneys may not handle high acid levels |
| Children | Cleveland Clinic says keep pure ACV out of kids’ reach because it can burn skin and mouth |
| In trials | The 2021 review says only two trials reported side effects, such as stomach burning and intolerance |
Cleveland Clinic’s source adds that ACV has not been approved to treat any health condition.
Who should talk to a clinician first?
- Anyone taking insulin, diabetes medicines, diuretics, laxatives or blood pressure medicines, since the pages above list interactions with these.
- People with low potassium, kidney disease, gastroparesis or frequent heartburn.
- People with type 2 diabetes. Most of the blood sugar findings come from this group, and one reviewed trial tested ACV alongside metformin rather than in place of it.
- Pregnant or breastfeeding women, children and teenagers. The 2025 weight meta-analysis excluded these groups, so its results do not cover them.
A clinician is the right person to decide whether ACV fits alongside your treatment. Nothing here suggests changing a prescribed medicine.
What is still unknown?
- Long-term effects. Trials stopped at 12 weeks.
- The right dose. Studies disagree, and dose did not clearly predict results in the 2021 review.
- Whether pills, gummies and powders work like liquid. The weight review notes that different forms may have affected results.
- Whether results differ for women or by age. The weight review could not split data by sex or age.
- Whether it changes belly fat itself. Fat mass was reported in only one trial.
- How much of the effect comes from the drink itself versus diet advice, placebo effect or eating less because of nausea. WebMD raises these possibilities.
For help judging numbers like HbA1c or cholesterol, see our guide to surrogate outcomes in trials. A lab number moving is not the same as fewer heart attacks or complications.
How to read a label that lists apple cider vinegar
- Amount: Trials used liquid volumes (mL). Check whether a pill or gummy states how much ACV, or only a powder weight, per serving, and how many servings a day the label directs. Compare that with the trial amounts above before assuming it is similar.
- Form: Liquid vinegar is about 5% to 6% acetic acid, per Cleveland Clinic. West Virginia University Extension says many vinegar pills contain too little acetic acid or direct you to take too much.
- Oversight: WebMD and Cleveland Clinic note the FDA does not regulate these supplements the way it regulates drugs, so contents can differ from what the label implies. WebMD suggests looking for a stamp from independent testing groups such as USP or NSF.
- Marketing claims: Our guide to ingredient evidence versus marketing claims explains how to separate what a label implies from what trials measured.
By ClinicalStudyConnect.com Research Desk
This article is for general information purposes only and does not constitute medical advice. Consult your doctor or qualified healthcare provider before making changes to your health routine.