Supercharging your body’s defenses against illness is easier than you may think: Simply draw a relaxing bath. Soaking in warm water spiked with apple cider vinegar raises the body’s pH to a level that makes it a less hospitable environment for bacteria and viruses. I advise doing the following twice a week during cold and flu season: Run a tub of the hottest water you can stand and add 2 cups of organic apple cider vinegar. Soak until the water is cool, and avoid showering for at least 4 hours to allow the vinegar to absorb into your skin.