It has been found that the pH factor (the acidity factor) of the body becomes a bit more alkaline prior to a cold or flu striking you down. When you take apple cider vinegar it helps to rebalance the acid level of your body.

Another remedy for colds and flu, and said to be specifically beneficial for chest complaints during the winter, is to soak a piece of brown paper with apple cider vinegar, and to place pepper on the one side of the paper. You then tie the paper, pepper side down, on to your chest and leave on for 25 - 30 minutes.