Broccoli would be an excellent example of a food with naturally occurring calcium
There really is no need to add lactol(which isn't exactly a healthy extra anyways,especially not compared to simple and pure foods like broccoli).Not only would broccoli add beneficial calcium,it would add healthy dietary fiber and protein among many other things.I think if you took time to figure out the benefits of various hamster safe fresh foods you could sort a perfect variety to work with and get what you're looking for!