UNITED STATES – On TikTok, a man swirls a tablespoon of apple cider vinegar into a cup of water, drinks it and eats two slices of pizza. Then, he tests his blood sugar. “These are the best results of all,” he says, showing a much lower spike on a blood sugar graph than when he ate the pizza without the vinegar.

In other posts, TikTok users rave about apple cider vinegar’s remarkable ability to help them lose weight, settle their stomachs and – when applied to their skin – clear their acne and eczema.

Apple cider vinegar has been used as a home remedy for healing wounds, quelling coughs and soothing stomachaches for thousands of years, said Dr Carol Johnston, a professor of nutrition at Arizona State University.

But while some of the health claims have a little science behind them, she added, many have not been studied.

Here is what people know about apple cider vinegar, and some important cautions to keep in mind if you try it.

How might apple cider vinegar benefit health?

Apple cider vinegar is made via fermentation, in which yeast and bacteria convert carbohydrates first into alcohol and then into acetic acid, which gives vinegar its pungent taste, odour and potentially, research suggests, its health benefits, Prof Johnston said.

Social media proponents often recommend using unpasteurised and unfiltered versions, which contain a haze of bacteria and undigested carbohydrates called “the mother”, said Dr Chris Damman, an associate professor of gastroenterology at the University of Washington School of Medicine. But there is no evidence that “raw” apple cider vinegar is healthier than regular ones, he added.

Vinegar made from apples and other fruit also contains compounds called polyphenols, which have antioxidant and anti-inflammatory properties and might contribute to potential health benefits, he said.

What does the research suggest?

Blood sugar control

In the early 2000s, Prof Johnston, who had been studying how certain diets could help manage Type 2 diabetes, came across a study from 1988 showing that acetic acid could lower blood sugar spikes in rats after they were given a starch solution.

She was intrigued and decided to test the idea in people with Type 2 diabetes and insulin resistance.

Since then, she and other researchers have found in small, limited studies that drinking one to two tablespoons of apple cider or other types of vinegar mixed with water just before high-carbohydrate meals resulted in less drastic blood sugar spikes than meals without vinegar did.

Weight loss

Several small, short-term studies in adults who were classified as overweight or obese have found associations between apple cider vinegar and weight loss.

In a 2009 study of 155 adults in Japan, for instance, researchers found that those who drank two tablespoons of apple cider vinegar in water every day for three months lost about 1.8kg. And in one 2024 trial of 120 people ages 12 to 25 in Lebanon, researchers reported that those who took one tablespoon of apple cider vinegar with water each morning for three months lost an average of 6.8kg.

But the one study that tracked participants after they stopped taking apple cider vinegar found that, on average, they regained most of the weight within a month.

And just as many studies on similar groups of people have found no links to weight loss.

Given the lack of robust data and the short time frames of the studies, Ms Beth Czerwony, a dietitian at the Cleveland Clinic, said she did not recommend that her patients use apple cider vinegar for weight loss.

If vinegar does indeed help people lose weight, it may do so by slowing digestion, which can make one feel fuller for longer, she added.

Gut health

Ms Tamara Duker Freuman, a dietitian in New York City who specialises in digestive conditions, said many of her patients remark that drinking apple cider vinegar before or after meals reduces their symptoms of acid reflux.

“I believe them,” she added. But, she noted, “hundreds of other patients with horrible reflux” have said vinegar worsened their symptoms.

Unfortunately, there is no good research on vinegar and digestive health, said Dr Nitin K. Ahuja, a gastroenterologist at Penn Medicine.

People who use vinegar to treat reflux, which is commonly caused by stomach acid escaping into the oesophagus, say the acid from the vinegar prompts the stomach to produce less acid, Dr Ahuja said. But, he added, there is no supportive data, and “mechanistically, it doesn’t make sense” that adding acid to the stomach will somehow help to control it.

If you have frequent or severe reflux symptoms, get treatment from a doctor, he said.

Skin conditions

Applying diluted apple cider vinegar to the skin has long been used as a home remedy for eczema, said Dr Lydia Luu, a dermatologist at the University of Virginia School of Medicine. And after several patients asked about such a treatment, she and her colleagues decided to test it.

In their 2019 study, the researchers asked 22 participants, half of whom had eczema, to soak one arm in tap water and one arm in diluted apple cider vinegar for 10 minutes a day for two weeks. Afterwards, there were no differences between the participants’ skin in terms of pH level, microbes or ability to retain moisture – all of which are typically altered in eczema. Sixteen of the participants reported symptoms like mild burning or itching, mostly on the arm treated with vinegar. One developed severe itching, moderate burning and a small sore, and another developed a raised rash.

Apple cider vinegar “is not very helpful for eczema, unfortunately”, said Dr Luu, and could make your symptoms worse.

Is it safe to try?

Consuming apple cider vinegar, even when diluted, can interact with certain medications, including some drugs for diabetes and the heart, as well as diuretics.

Apple cider vinegar may also lower blood potassium, which can be a problem for those who already have low levels, Ms Czerwony said. So check with your doctor before trying it, she added.

The same advice goes for using it on the skin, Dr Luu said. A primary care doctor or dermatologist can likely recommend safer, more effective treatments.

If you want to use vinegar to control your blood sugar, Prof Johnston suggested drinking one or two tablespoons of any type of vinegar diluted in water, but not to exceed two to four tablespoons in a day. Even when diluted, vinegar can erode tooth enamel, so she recommended drinking it with a straw.

If you drink it undiluted, you run the risk of corroding your oesophagus lining too, Dr Ahuja said.

A safer and tastier approach, Prof Damman suggested, is to use apple cider vinegar in your cooking. Mix it into vinaigrette or sushi rice, pair with olive oil as a dip for bread, or incorporate it into a refreshing fizzy drink.

If there are health benefits to be reaped, he said, you will likely get them this way too. NYTIMES