An important consideration when choosing a probiotic is survival – all OptiBac Probiotics are developed to survive gastric acidity above (more neutral than) pH 3. In general, at mealtimes the stomach’s gastric acidity is naturally at pH 4 or above. This means that there is 100% expected survival through the gastric acids of the stomach if taking probiotics with food.  It is therefore advisable to take OptiBac Probiotics with meals, preferably your breakfast.