Cleopatra is said to have dissolved a pearl in vinegar and drunk it, to prove to her lover Mark Antony that she was capable of downing an outrageously expensive meal. Another story says that Hannibal crumbled boulders with vinegar in order to cross the Alps.
Vinegar is obviously the stuff of legend, but here’s the real test of its powers: Is much-vaunted apple cider vinegar a potential aid against Type 2 diabetes?
Well, yes, in a way. There are numerous studies showing that vinegar can have a beneficial effect on blood glucose levels, though the effects might be more useful for people with pre-diabetes than those with diabetes. Though studies date back well 30 years, no reputable organizations are urging people to consume more of it. The American Diabetes Association hasn’t added it as a nutritional recommendation, and even those who have done the research on the condiment warn that people shouldn’t look to vinegar as a magic bullet for treating or avoiding diabetes. At its best, and used with care, it could be helpful as an add-on, they say, but it won’t replace a proper diet or other doctor-ordered treatments or lifestyle changes.
In fact, it’s not entirely clear why all the fairy-dust talk is about apple cider vinegar; researchers say any vinegar would do the same thing, though cider vinegar might be more palatable for many people. But the condiment seems to help only when taken before a high-carbohydrate meal.
Carol Johnston, a professor of nutrition at Arizona State University, has published several studies on vinegar. In a 2004 study published in the journal Diabetes Care, subjects downed four four teaspoons of apple cider vinegar in some water before a high-carb meal. Some of the participants had Type 2 diabetes, some were insulin-resistant and the rest had no diabetes issues. Compared with subjects who had a placebo drink before their meals, there were slight improvements an hour later in insulin sensitivity and blood-glucose levels among those with diabetes. But patients with pre-diabetes experienced much bigger differences.
A year later, a Swedish study gave subjects a meal (maybe more like an unappetizing snack) of white bread with vinegar. There were three separate groups, consuming vinegars with various levels of acetic acid – the stuff that makes vinegar so sour. Thirty minutes after their carb-and-vinegar repast, those who had been dosed with vinegar showed lower blood-glucose levels and improved insulin response – and also felt more satiated by their food, compared with a control group. And the higher the dose of acetic acid, the better the response.
According to Johnston, the vinegar appears to work by inhibiting the digestion of starch. But she recommends careful use of it for those who want to try it. One tablespoon of the stuff should be diluted in a cup of water, she told the New York Times in 2016, and taken with the first bites of the meal, before beginning to eat the starchy foods. It could also be used in the more traditional way: As part of the dressing on a small, low-carb salad before the main meal.
But taken by itself or in too large a quantity, it can, as it supposedly did to Cleopatra’s pearl, erode teeth; it also can injure the esophagus and cause nausea. Another important note: Vinegar might be all wrong for people with Type 1 diabetes. A 2007 study by a different Swedish research team found that vinegar caused delays in gastric emptying. That’s already a problem for some people with Type 1 diabetes. Vinegar could worsen the situation.
Centuries ago in Europe, a sweetening agent was used for wine (remember, they didn’t have boxes of granulated sugar in those days) by pouring vinegar over lead, which was called “sugar of lead.” It of course was highly poisonous. A story worth remembering about the importance of using vinegar judiciously.
(For a non-scientific – but fun – apple cider vinegar experiment, check out our editor Jessica Apple’s post.)