Research by nutritionist Carol S. Johnston of Arizona State University East in Mesa suggests one easy measure that might have a notable impact: Consume more vinegar. A few tablespoons of vinegar prior to a meal—such as part of an oil-and-vinegar salad dressing—could benefit people with diabetes or at high risk of developing the disease.
Her studies indicate that 2 tablespoons of vinegar before a meal—perhaps, as part of a vinaigrette salad dressing—will dramatically reduce the spike in blood concentrations of insulin and glucose that come after a meal. In people with type 2 diabetes, these spikes can be excessive and can foster complications, including heart disease
In Johnston's initial study, about one-third of the 29 volunteers had been diagnosed with type 2 diabetes, another third had signs that they could become diabetic, and the rest were healthy. The scientists gave each participant the vinegar dose or a placebo to drink immediately before they ate a high-carbohydrate breakfast consisting of orange juice, a bagel, and butter. A week later, each volunteer came back for the opposite premeal treatment and then the same breakfast. After both meals, the researchers sampled blood from the participants.
Once ingested, carbohydrates—sugars and starches—can quickly break down into glucose that builds up in a person's blood (see The New GI Tracts
). That's why people with diabetes frequently have to severely curb their carb intake. High-carbohydrate meals also prompt hunger to return earlier than low-carb meals do. Indeed, such observations spawned the low-carb diet craze (see Counting Carbs
Although all three groups in the study had better blood readings after meals begun with vinegar cocktails, the people with signs of future diabetes—prediabetic symptoms—reaped the biggest gains. For instance, vinegar cut their blood-glucose rise in the first hour after a meal by about half, compared with readings after a placebo premeal drink. In contrast, blood-glucose concentrations were only about 25 percent better after people with diabetes drank vinegar. In addition, people with prediabetic symptoms ended up with lower blood glucose than even healthy volunteers, after both groups drank vinegar.
In these tests, vinegar had an effect on volunteers' blood comparable to what might be expected from antidiabetes drugs, such as metformin, the researchers reported last January in Diabetes Care
. A follow-up study has now turned up an added—and totally unexpected—benefit from vinegar: moderate weight loss.
Both findings should come as welcome news during this season when sweet and caloric treats taunt diabetics, who face true health risks from indulging in too many carbs.
In a pickle
Why vinegar? A nutritionist, Johnston was looking for possible diet modifications that would make meals less risky for people with diabetes. While reviewing research published earlier by others, she ran across reports from about 2 decades ago that suggesting that vinegar limits glucose and insulin spikes in a person's blood after a meal.
A few research groups had conducted limited follow-up trials. For instance, Johnston points to a 2001 paper in which researchers at Lund University in Sweden evaluated pickles—cucumbers preserved in vinegar—as a dietary supplement to lower the blood-sugar rise in healthy people after a meal. The Swedish team, led by Elin M. Östman, reported that pickles dramatically blunted the blood-sugar spike after a high-carb breakfast. Fresh cukes didn't.
"I became really intrigued," Johnston says, because adding vinegar to the diet would be simple "and wouldn't require counting how many carbs you ate." t first, she attempted to replicate findings by others, focusing specifically on people with diabetes or prediabetic symptoms.
When these individuals showed clear benefits from vinegar after a single meal, Johnston' group initiated a trial to evaluate longer-term effects. It also explored vinegar' effect on cholesterol concentrations in blood. The Arizona State scientists had hypothesized that by preventing digestion of carbs in the stomach, vinegar might cause carbohydrate molecules to instead ferment in the colon, a process that signals the liver to synthesize less cholesterol.
So, in one trial, Johnston had half of the volunteers take a 2-tablespoon dose of vinegar prior to each of two meals daily for 4 weeks. The others were told to avoid vinegar. All were weighed before and after the trial.
As it turns out, cholesterol values didn' change in either group. To Johnston' surprise, however, "here was actually about a 2-pound weight loss, on average, over the 4 weeks in the vinegar group." In fact, unlike the control group, none in the vinegar cohort gained any weight, and a few people lost up to 4 pounds. Average weight remained constant in the group not drinking vinegar.
Johnston would now like to repeat the trial in a larger group of individuals to confirm the finding, but that study is currently on hold.
Why? To no one's astonishment, the study volunteers didn't like drinking vinegar straight—even flavored, apple-cider vinegar. Indeed, Johnston says, "I would prefer eating pickled foods or getting . . . vinegar in a salad dressing." Now, the scientists are developing a less objectionable, encapsulated form of vinegar and testing its efficacy. Although there are commercially available vinegar dietary supplements, Johnston notes that they "don't appear to contain acetic acid," and based on studies by others, she suspects that's the antidiabetic ingredient in the vinegar.