All of these lead to an excessive loss of calcium from your body and a decreased rate of absorption. Eat foods containing oxalic acid in moderation. Oxalic acid interferes with calcium absorption. Foods containing oxalic acid include almonds, beet greens, cashews, chard, kale, rhubarb and spinach. Use wheat bran in moderation.
Excessive amounts can interfere with calcium absorption.
Check your prescription medications. Some, such as glucocorticoids, can interfere with calcium absorption. Discuss supplementation with your doctor. Antacids are not a good source of calcium because they neutralize stomach acid, and calcium needs the acid in order to be properly absorbed. Aluminum containing antacids may cause increased calcium excretion.