I am selectively lactose intolerant; among the dairy foods that upset my stomach are ice cream, regular yogurt, and whole milk; if I eat either of those items without taking Lactaid or a similar supplement, I get an upset stomach. I thought that I was sentenced to a life of frozen yogurt. :D
One day, I tried some gelato and it not only tasted good, but my stomach was just fine! When I looked up the ingredients, I was surprised to find out that it was made from milk. I tried it again, thinking it was a fluke, and my stomach was still fine.
I did further research and read about the lower butterfat content of gelato vs. that of American ice cream and other dairy products. This, combined with the real-time effects (or lack thereof) on my digestive system have made me a gelato fan for life. I'd recommend that other lactose-intolerant people give it a try for themselves.