1. Dark greens
You can get an abundance of calcium from way more than just milk and cheese. It is actually found in high concentrations in many different vegetables. A few examples are Chinese cabbage, turnip greens, kale, collard greens, and bok choy.
These dark leafy greens also offer a nice dose of vitamin K, which works together with calcium to boost bone density. You can get even more vitamin K in broccoli, asparagus, and Brussels sprouts.