I take enzymes when I have digestive trouble. There are various different products on the market with different digestive enzymes. Some work on dairy, some on protein and others on carbs. I don't always have problems with dairy, but once in a while, my stomach acts up and dairy causes cramps and excess gas. When that happens, I take a few capsules of digestive enzymes and I'm back to normal in no time.
I don't take anything else for my digestive system. But I do eat healthy and consume a lot of fiber rich foods. Aside from the vitamins mentioned here, fiber is the most beneficial thing for the digestive system. It feeds beneficial bacteria in our stomach and intestines so that they can work efficiently.