Vinegar is often included in fad diets -- and has been since the 1800s. Even though starving yourself, drinking vinegar water and eating just a raw egg in tea isn't good for you, as Lord Byron recommended in the 1820s, according to the American Dietetic Association Fad Diet Timeline, vinegar itself does have some beneficial properties. In fact, taking vinegar at bedtime may be beneficial if you have diabetes or prediabetes. Always consult a health care provider before trying a new therapy or altering your diet, especially if you have a health condition.
Taking 2 tbsp. vinegar at bedtime may favorably affect your waking blood-glucose level if you have Type 2 diabetes, according to a 2007 study published in "Diabetes Care." In fact, it may reduce your fasting blood-glucose level by as much as 6 percent, according to lead study author Andrea M. White. Vinegar appears most effective if your fasting blood-glucose level is on the higher side. People participating in the study who had lower fasting blood-glucose levels had changes as slight as .7 percent.
Acetic acid is the active component in vinegar that's responsible for its blood-sugar lowering effects, according to White. Acetic acid is found in white, apple cider and other varieties of vinegar. Acetic acid is a carbon-based compound that features a single ionizable proton. It's classified as a carboxylic acid, which is a classification for certain organic acids. The federally required minimum concentration for acetic acid in vinegar is 4 g per 100 mL.
Acetic acid reduces glycemic responses to meals by a mechanism related to acidity, according to a 1995 study in the "European Journal of Clinical Nutrition." Another scientific theory on its blood-sugar lowering effects is that it delays stomach emptying time, White notes, though the 1995 study did not find this to be the case. However, neither of these possible mechanisms explains why vinegar has a blood-sugar lowering effect apart from mealtimes, such as overnight, according to White.
Theories and Considerations
White theorizes that acetic acid alters your body's glycolysis or gluconeogenic cycle, meaning it helps your liver and muscles extract glucose from your bloodstream and thus reduce the amount of glucose in your blood. This alteration may help you if you are a diabetic person with metabolic disturbances that contribute to the "dawn phenomenon," or a prebreakfast rise in fasting glucose levels.
White also notes that reductions in fasting glucose produced by vinegar are less than those observed in trials for pharmaceutical hypoglycemic agents. Such agents can reduce fasting glucose 10 to 15 percent with long-term therapy. Vinegar can have an additive effect to hypoglycemic drugs, according to White. More research is needed on vinegar's possible benefits if you have diabetes, White notes, because the 2007 study was small and of short duration.