Not enough calcium is the reason why some people get kidney stones. Oxalates will pull calcium from your bones and make crystals which can build up and cause a variety of issues, not just stones. Veggies are great and all and probably do provide quite a bit of calcium but when you break down meal for meal..a lot of those veggies are packed with oxalates and the balance is way off. whenever you eat a lot of oxalates, you should be eating calcium so that they bind together in the gut and get expelled.. if this balance is screwed up for a long period of time, then oxalates build up.. if you have leaky gut they get into your blood and migrate
Calcium is not just for bones and teeth..its for digestion and numerous other functions in the body
I think the recommended 1000mg/day is not far fetched at all