Yes, you can find loads of calcium in plant foods! Kale is one of the best sources—one cooked cup packs 177 mg of calcium, while one raw cup delivers 53 mg. It’s even more bioavailable than the calcium in milk, meaning your body has an easier time absorbing it, says Connie M. Weaver, PhD, distinguished professor and department head of nutrition science at Purdue University.
Not all greens are created equal, though. Oxalic acid—which is prevalent in plants like spinach, chard, and beet greens—binds to calcium, which can mess with your body’s ability to absorb it properly. Even though spinach technically has a lot of calcium, it’s only a tenth as bioavailable as that from milk because of the oxalic acid, says Dr. Weaver, “so it’s a terrible source of calcium.”