Check out the recipe for the Cleansing Drink in the FAQ. The enzymes in organic apple cider vinegar really ensure that your body doesn't get all out of whack when contamination strikes. Several users have posted that they stayed well while their entire family got sick because they made sure to drink the drink prior to retiring for the evening. :)
If you wish to take further measures, a bit of digestive enzymes and live acidophilus would also help.