Children and adolescents need 1,300 milligrams to build and grow strong bones and calcium stores. Pregnant and breast-feeding women need only the amount recommended for their age. Most Americans do not get enough calcium in their diets, especially women. When calculating the amount of calcium you get in your diet, keep in mind that certain dietary factors, lifestyle characteristics, medical conditions and medications can affect the absorption or excretion of calcium in your body. Protein and sodium in foods boost the amount of calcium excreted in urine, while phosphorus an vitamin D reduce the amount excreted in urine.
Caffeine reduces the absorption of calcium.
Cigarette smoking may decrease the absorption o calcium. Diseases such as hyperthyroidism and diabetes, and medicines such as corticosteroids and glucocorticoids reduce the absorption of calcium, and increase the amount excreted in urine. Alcohol in moderation does not appear to adversely affect calcium availability. If you are not getting enough calcium in your diet, you should take a supplement. They do not provide the same overall nutrient benefits as foods, however.