(CNN)Apple cider vinegar is one of the most popular natural health products around, with claims for everything from sanitizing toothbrushes to whittling waistlines.
But how much of its popularity is based on hype? Could you be wasting your time or — even worse — harming your health?
Here are 10 of the top ways people are using apple cider vinegar and what the science says.
What’s the most popular use for apple cider vinegar? If a simple internet search is any measure, it involves diabetes.
Dietitian Carol Johnston has been studying the effects of the main component of any vinegar, acetic acid, on diabetic blood glucose levels since 2004. She’s conducted 10 small randomly controlled studies and published six papers on the subject.
Her studies indicate vinegar can help lower blood sugar in people with type 2 diabetes; in those who are prediabetic, also called insulin-resistant; and even in healthy control subjects. The improvement was slight for all but those at risk for diabetes, she says.
“In pre-diabetics, it was too good to be true,” says Johnston,who is also associate director of the Arizona State University’s School of Nutrition and Health. “It fell a good bit and stayed that way. It may be this is the group that could benefit the most.”
But this antiglycemic response can be induced by any sort of vinegar, she says: red and white wine vinegars, pomegranate vinegar or even white distilled vinegar. She suggests adding it to salads, as in the Mediterranean diet, or diluting it in water and drinking it before a meal.
“Basically, what acetic acid is doing is blocking the absorption of starch,” Johnston says. “If my study subjects eat a starch and add vinegar, glucose will go down. But if they drink sugar water and add vinegar, nothing happens. So if you’re having bacon and eggs, don’t bother. It only helps if you are consuming a starch.”
If you choose to use apple cider vinegar, be sure to tell your doctor, says nutritionist Lisa Drayer.
“If you’re taking a diabetes drug, the vinegar could amplify the effects of your meds,” she warns, “and your doctor might want to adjust your dosage.”
Most important, if you’re expecting vinegar to significantly alter or prevent diabetes, science suggests you reconsider.
Johnston notes that there is no evidence, in her studies or others, to establish that connection.
“I simply determine if your glucose level goes up and down,” she says. “If I was to show that vinegar slows progression to diabetes, then I would need hundreds of people and millions of dollars to do the studies, because diabetes has a lot of causes, including genetics.”
Weight loss, or dieting, is another popular use for apple cider vinegar and there is some evidence that it can help.
The most cited study was done with 175 heavy but otherwise healthy Japanese subjects. The 12-week treatment produced lower body weight, body mass index, visceral fat, waist measurements and triglyceride levels. Sounds great, right?
“People didn’t really lose that much weight,” Drayer says. “Only 2 to 4 pounds in three months over a placebo. That’s only a third of a pound a week.”
Johnston agrees the study showed “a very, very modest weight loss.’
“In fact, I would say most people who are on a diet for 12 weeks and only lose a couple of pounds aren’t going to be very happy,” she adds.
If you are using apple cider or other vinegars as one part of an overall plan, combining it with a healthy diet, portion control and exercise, it might help, Drayer says. She suggested using balsamic vinegar on salads, in a 4:1 ratio with oil, or adding it to sauces for poultry and fish.
“If you were doing all the other things to lose weight, it might give you a slight edge,” Drayer says. “Also, if you’re drinking it in water, that’s good, as water makes you feel full.”
“Sometimes, people get really excited to try something new, and then their other behaviors change, too,” she adds. “So if this helps people be more careful overall, that’s a good thing.”
Teeth cleaning and whitening
“Some people like to use it to remove stains and whiten their teeth,” according to one of many online articles touting apple cider vinegar for this purpose: “To try this, rub a small amount of apple cider vinegar onto your teeth with a cotton swab.”
“I let out an audible gasp when I read about this!” says Chicago dentist and American Dental Association spokeswoman Alice Boghosian. “It made me cringe, to be honest with you. What are people doing?”
“You’re putting acid on your teeth,” Boghosian continues, “the last thing you’d want to do to promote oral health. What would be a healthier option is to brush your teeth twice a day for two minutes, with a whitening toothpaste with the ADA seal. That shows it’s been tested to do what it’s supposed to do.”
Other articles promote rinsing your mouth with apple cider vinegar, soaking dentures with a diluted mixture or using it to clean a toothbrush.
“You just have to rinse off your toothbrush, get all the toothpaste out, and let it air out. That’s all you have to do,” Boghosian says. “Cleaning dentures or rinsing with vinegar is not a good idea. It too could put your teeth at risk. And just think how it might affect the metal on partial dentures.”
A pH of 7 is neutral, explains Boghosian; anything less is acid. She said many of today’s popular apple cider vinegars are in the 2 to 3 range — about the same as stomach acid.
“Anything acidic which contacts your teeth will wear out the enamel, the protective coating, and that will cause cavities,” Boghosian adds. “So, this is totally, completely wrong, unless you want to be paying more visits to your dentist.”
Skin, hair and nails
Commonly suggested uses for apple cider vinegar across the internet include it’s useas a treatment for skin infections and acne, fighting lice and dandruff, as a natural wart remover and as an anti-aging treatment.
“It will dry out a pimple, but it’s not an anti-aging method,” says dermatologist Dr. Marie Jhin, a spokeswoman for the American Academy of Dermatology. “It might fade dark spots, or maybe you could use it as a skin toner, if you dilute it a great deal. But I wouldn’t recommend it. We have much more effective and safe methods today than this.”
One use she can agree with: “I do love it for bites, especially mosquito bites. It’s a very underutilized home remedy. If you have a lot of bites, put two cups in a full tub of water and soak. It will help with itching,” she says.
“It can also help with sunburn, although there are so many other good remedies,” Jhin adds. “We don’t usually suggest that to patients.”
Apple cider vinegar might help with dandruff, says Jihn, because the acidity could increase the sloughing of the skin on the scalp, and it does have some antifungal properties.
But don’t turn to it to get rid of head lice. One study found the use of vinegar to be the least effective method among several natural solutions; only petroleum jelly killed adult louse, but it did next to nothing to fight the eggs.
Another use Jhin recommends:”I love vinegar for paronychia, an infection under the cuticle that a lot of people get,” Jhin says. She suggests mixing one-fourth cup of vinegar with three-fourths cup of water and soaking nails.
But what about warts and other home uses?
“Warts are caused by a virus, so there’s no cure,” Jihn explains. “You can dab a diluted version of apple cider vinegar on a wart with a Q-tip, and it’s going to help remove dead skin, which is what we do in the office by paring it down, cutting it out or burning it with liquid nitrogen. But it’s not going to be as fast or effective as what we do in the office.”
American Academy of Dermatology spokesman Dr. Michael Lin, director of the Advanced Dermatology and Skin Cancer Institute in Beverly Hills, has a more negative perspective on home use.
“I’ve had quite a few patients harmed by apple cider vinegar,” Lin explains. “One terrible example was a man trying to treat genital warts. When he came into the office, the entire area was raw, burned by the vinegar.
“I don’t know if he was using it full-strength, but whatever he was doing it was too strong,” he continues. “He probably has permanent scarring from that natural home treatment.”
Lin says he feels more comfortable recommending distilled white vinegar, as it is created to a standardized formulation of 5% acidity.
“With apple cider vinegar, you don’t know what strength you’re getting,” Lin says. “It’s depends on the brand, and even among batches within a brand, you could get different concentrations of acidity.”
“If you do choose to use apple cider vinegar, try to buy a name brand that clearly labels the acidity level. And whatever you do, don’t use it full-strength.”
He suggests a 1:10 ratio.
Because of apple cider vinegar’s antimicrobial properties, it is often suggested as a natural cleanser for the home.
The acid is effective against mold, but according to the Pesticide Research Institute, an environmental consulting firm, so are salt, lemon juice, hydrogen peroxide, tea tree oil and baking soda.
Many of those also smell better.
Apple cider vinegar is biodegradable, and because of its low pH, it’s great against alkaline grime such as hard water and mineral deposits, as well as soap scum.
But it won’t cut grease. Why not? Just think of a simple oil and vinegar salad dressing. After mixing, the oil and vinegar quickly separate because oil is nonpolar, while vinegar and water are polar, meaning they are not attracted to each other.
Will apple cider or other vinegars sanitize or disinfect your home? Probably not enough to make you feel germ-free.
This 1997 study showed that undiluted vinegar had some effect on E. coli and salmonella, but a study conducted in 2000 showed no real impact against E. coli or S. aureus, the common staphylococcus bacteria responsible for most skin and soft tissue infections.
That2000 study also showed vinegars to be quite effective against the waterborne bacteria Pseudomonas aeruginosa, mostly found in hospitals and untreated hot tubs. It was also effective against Salmonella choleraesuis, a rare pig-borne version of salmonella.
If you do choose to use a vinegar to clean your home, never mix it with bleach or ammonia, because it will create toxic chlorine or chloramine gases.
Used for centuries to preserve everything from pickles to pig’s feet, vinegar is now becoming popular as a natural preservative in processed meat and poultry items as well.
Most home pickling uses 5% distilled white vinegar because it doesn’t affect the color of the vegetables or fruits, but apple cider vinegar is a popular choice due to its mellow, fruity flavor. Do know, however, that it will turn most fruits and veggies dark.
Another popular use for apple cider, and other vinegars, is as a food wash to reduce bacteria or viruses on the surface of fruits and vegetables. Studies have had varying results, often depending on the type of fruit or vegetable and the amount of time spent in the vinegar solution.
After listing a number of studies and results, the US Food and Drug Administration sums it up: “Vinegar and lemon juice have potential as inexpensive, simple household sanitizers; however, possible negative sensory effects [color, odor] when used on produce would be a disadvantage.”
Cough and sore throat
The use of vinegar medicinally starts with the father of modern medicine, Hippocrates. He would mix it with honey and use it for chronic coughs and sore throats, and the suggestion continues today across the internet.
Many parents might think this is a natural and safe option for their children. The American Academy of Pediatrics doesn’t have an official stance on the use of apple cider or other vinegars as a health aid, but spokeswoman Dr. Jennifer Shu urges caution.
“I would just think that the vinegar would irritate the throat even more,” says Shu, an Atlanta pediatrician and author of “Food Fights”. “But diluting it and mixing it with other ingredients such as salt or honey might decrease any pain that the vinegar might cause.”
The University of Arizona’s Johnston cautions against trying any vinegar straight, due to the risk of inhaling the liquid and damaging the lungs.
“Vinegar has that strong smell and puckering taste, so if you take a breath, you could inhale it into your lungs as you swallow,” she says. “It can burn the lungs a little, because it is an acid.”
“It can also burn your esophagus,” says Dr. Andrew Freeman, director of cardiovascular prevention at National Jewish Health in Denver, Colorado. “And if you’re predisposed to reflux, ulcers or stomach problems, it could certainly make those worse.”
Heart disease and cancer
If you’re a rat worried about heart disease, put apple cider and other vinegars on your shopping list.
Studies show the vinegar can reduce blood pressure, triglycerides and total cholesterol in rodents fed a high-fat, cholesterol-rich diet. But similar studies have not been conducted in humans.
Freeman, who serves on the American College of Cardiology’s prevention board, says there could be some benefit due to its antioxidant properties, like other heart-healthy fruits and vegetables, such as broccoli and blueberries.
“The data is not particularly strong or overwhelming, but vascular health may be enhanced,” Freeman says. “What’s best to avoid heart disease is to exercise and eat a low-fat, plant-based diet.”
Freeman further recommends using apple cider or other vinegars on salads, to maximize the benefits and reduce any reactions to the acidity.
What about cancer? Japanese scientists have inhibited the growth of human leukemia and other cancer cells in Petri dishes by exposing them to sugar cane vinegar and Japanese rice vinegar. Other studies showed a reduction in tumors and a prolonged life by adding rice vinegars to drinking water and food in rats and mice respectively.
Studies in humans are nonexistent.
So, does apple cider vinegar measure up to its positive internet reputation? If you consider that almost any other vinegar will produce the same benefits, not so much.
There arealsosome serious downsides, if used full strength and inappropriately. As the experts suggest, make sure you check with your doctor before giving it a try.
“When do you a search for apple cider vinegar you see so many claims, and people will try it, searching for that natural cure-all,” says Drayer.
“Whether any of those claims are based on science is another matter.”
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