The problem of calcium requirement.
D002118:Calcium / Q000172:deficiency / Q000378:metabolism / Q000502:physiology*; D002136:Calcium, Dietary / Q000008:administration & dosage*; D005215:Fasting; D006801:Humans; D009751:Nutritional Requirements; D010024:Osteoporosis / Q000209:etiology / Q000378:metabolism
D002136:Calcium, Dietary; D002118:Calcium