It should also be mentioned that high oxalic acid-containing food sources such as spinach, rhubarb, beet greens, or chards can have a very negative impact on individuals who have difficulty maintaining adequate levels of calcium. As a result, they are equally at risk to develop osteoporosis since oxalic acid binds to calcium and so reduces its absorption. Kale, broccoli, or collards are a better choice in such cases... Full Text