1. It’s not very nutritious—and it won’t melt off your fat (or do most of the other crazy things you’ve read online).  Sorry, devotees, but nutritional analyses show that ACV has little to no fiber, vitamins, or minerals. There’s also very little evidence to support claims that ACV can help you shed pounds. In one Japanese trial—the only study done to date to test the ACV–weight loss hypothesis—subjects took a daily dose of either ACV or water for 12 weeks. The vinegar group lost 1 to 2 pounds—not exactly a weight loss triumph. Could it cause more weight loss over a longer period of time? Maybe! We just don’t yet have any studies prove it. Most other claims—that it detoxes the body, fights cancer, fights colds, fights allergies, prevents acne, relieves arthritis, etc.—are totally unsupported. (Here are 10 more food and healing myths.)
  2. The good news: It can help with blood sugar control and nutrient absorption. ACV isn’t all smoke and mirrors! “Apple cider vinegar has been shown to significantly lower blood sugar and insulin responses when eating a high carb meal and at bed time,” says Sharon Palmer, RDN, author of The Plant-Powered Diet. Studies also show it can enhance your body’s uptake of calcium and may help you feel fuller after you eat. 
  3. You could hurt yourself if you use it wrong.  Case studies in medical journals (and a lot of panicked posts on Yahoo Answers) show that, because ACV is acidic, it can cause tooth enamel erosion and burn the skin and esophagus. That means you’ve got to swig and scrub carefully. Whether you’re drinking ACV or using it as part of a beauty routine, make sure you dilute each tablespoon with at least 8 ounces of water.  MORE: 4 Things That Happen When You Drink Apple Cider Vinegar with Every Meal
  4. There are ACV supplements—but you definitely shouldn’t buy them. Supplement companies looking to capitalize on ACV fever sell capsules that purportedly contain “high potency” doses of the stuff. Promises on the labels include “enhances energy and vitality” and “high powered system cleanser” (ew). (Also, you should never go on a juice cleanse.) But savvy shoppers already know that FDA does not require supplement makers to get any kind of approval before they put products on the market. That means all those crazy claims on the bottle are highly suspect. Unsurprisingly, a study in the Journal of the American Dietetic Association tested 8 different brands of ACV tablets and found they varied widely in acidity. The researchers even wondered whether ACV was actually an ingredient in any of the pills. Besides, why would you shell out extra for supplements when you can buy the real thing—a safe food product that is regulated by the FDA—for less?
  5. It can interact with certain drugs.  If you take insulin, digoxin (a drug used to treat irregular heartbeat), laxatives, or diuretics, overdoing it on the ACV could be a problem—experts say to you should ask your doctor before starting any kind of regimen. It may also affect bone density, so people with osteoporosis may want to steer clear, too. Overall, through, ACV is generally pretty innocuous. A couple tablespoons a day is safe, Palmer says. 
  6. It’s super easy to mask its strong flavor.  For the uninitiated, astringent ACV can be a little hard to choke down. But when it’s properly balanced with other ingredients, the vinegar is actually pretty delicious. It’s perfect for making pickled veggies and roasted ones, too. It also adds punch to sauces and condiments, like this barbecue sauce and this bacon jam. Swap out lemon juice or balsamic in your usual salad dressing for ACV, or add a tablespoon to soups or smoothies. Some recipes even call for ACV in meat marinades—it’s a perfect match for chicken breasts and pulled pork. (ACV also stars in this avocado-egg salad we can’t stop salivating over.) In short: If you’re interested in infusing more ACV in your life but can’t stand the taste, try subbing it in anytime a recipe calls for an acidic ingredient.