My stomach is very sensitive to certain foods, particularly dairy products. The problem is, that I absolutely love cheese, milk, and pretty much every kind of dairy food out there. I mean, my idea of an ideal meal is made up of a bean and cheese burrito, and an extra cheesy enchilada. So, instead of giving those foods up, I take supplements to counter the effects. Lactaid Fast Act Lactase Enzyme Supplement effectively keeps me from having an upset stomach if I remember to take them when I first start eating. The main drawback to taking this instead of another more expensive supplement, is that it requires you to take one every time you eat something that might have a dairy product in it. In fact, there are times when I have to take more than one at a time, if I am going to eat a really cheesy food. This makes it a bit inconvenient, because you have to open the little packet right when you begin your meal. It's not a big deal, unless you are a bit forgetful. All in all, it does its job.