1. ACV can erode your oesophagus, cause permanent irritation of the tissues of the oesophagus which can lead to cancer, or erode the lining of your stomach.
ACV contains 5% acetic acid, the same as any other table vinegar. This acidity level is quite low, especially compared to the vinegars used in pickling which are typically in the order of 18% acidity.
I don’t imagine that drinking ACV would be any worse for a person’s oesophagus or general system than drinking say Coca Cola, which for instance has a pH of 2.5 and is of similar acidity to hydrochloric acid.
ACV can not erode your stomach lining – even taken straight (which isn’t recommended) it has an acidity level (pH 2.4) about 15 times lower than the gastric juices (1.0), natively produced in the stomach.