Is brushing teeth within half an hour of acidic beverage consumption harmful?

Hello doctor,

Please tell me if this statement is true or not. I have been told that if you brush your teeth within a half hour after drinking or eating anything acidy, such as coffee, beer, or tea, it could actually brush the acid into your teeth, causing more damage than brushing. The problem is that after each meal, I usually have the time to brush my teeth. A half-hour later, I am involved with something else and my teeth are the last thing that I am thinking about. Neither my dentist nor anyone else has directly answered my question.