Milk calcium has three major benefits: it is well absorbed by the intestine, it is bioavailable for bones, and the majority of milk products contain considerable quantities. However, many plants contain substances (such as oxalates, phytates …) that prevent the absorption of calcium (absorption coefficient of milk is 32,4%; spinach and water cress 5% to 13%). In addition, they contain much less calcium than dairy products (for 300 mg calcium you need ¼ liter of milk, but 850 g of cabbage or 3 kg of oranges). Calcium in plants usually does not have the same beneficial bioavailability as dairy calcium (with the exception of kale and broccoli), nor a similar bone retention (good ratio of Ca/P in milk).