Does drinking apple cider vinegar help your digestion?

No single study in the available literature has directly examined whether drinking apple cider vinegar improves digestion. The widespread feeling among so many people that it helps has therefore not been scientifically confirmed. There is simply no evidence that apple cider vinegar makes your gut work better, settles your stomach, or improves the digestion of food.

What has been studied are the effects on blood sugar. An analysis of nine randomised studies shows that apple cider vinegar lowers fasting blood sugar by an average of nearly 8 mg/dL, and a measure of long-term blood sugar control (HbA1c) by 0.5 units. That effect was most pronounced in people with type 2 diabetes and with use of more than eight weeks. In healthy people, blood sugar appeared to rise slightly instead. Total cholesterol fell modestly, but there was no effect on 'bad' LDL cholesterol or insulin.

Fermentation of apples can improve the absorption of certain plant compounds in the laboratory, but this has not yet been demonstrated in humans and says nothing about a concrete digestive benefit.

One safety point deserves attention. Apple cider vinegar tablets are not reliable: research into eight brands found large differences in acidity and labelling, and it was sometimes even unclear whether the tablets actually contained apple cider vinegar. There is also a report of oesophageal damage following use of such tablets. The health claims on packaging were unsubstantiated. Liquid apple cider vinegar is highly acidic and can erode tooth enamel with regular use; diluting it in water is therefore advisable.