This topic has been debated endlessly, with various probiotic packaging completely contradicting each other on the refrigerator shelves. There is actually no specific study that looks into this, but great results from probiotics have been garnered when using probiotics with food. Here are some thoughts to clear this up.
The pH of the stomach is quite acidic (between 0.8 and 2) when our stomach is empty, which quickly kills probiotics. After 60 minutes in a pH of 1.5 in simulated gastric juices, all freeze-dried probiotics die unless they have some form of protection applied to their capsule.
Food buffers stomach acid, and in fact after food, gastric pH is between 4 and 7. Food also contains ‘food’ for the probiotics, which can provide a food source for bacteria on their way through. Typically, fermented foods are laden with probiotics, and probiotic bacteria would never normally be taken by themselves. Many bacteria also secrete enzymes that aid in the digestion of food.
We reckon taking your probiotics with food is the best way to take them.