Ethel Siris, MD: The best sources of calcium are dairy foods. If you get three servings of dairy a day, you're probably where you need to be.But if you don't get enough dairy or if you can't take dairy, then you would have to supplement your diet to get enough calcium.Yes, there's calcium in the bones of sardines and bony fish.Yes, there's calcium in certain greens, bio available in some greens and not in others, but you'd have to eat a lot of broccoli everyday.It may be simpler to buy a supplement, but again, you supplement your diet.If you need a total of 1,200 milligrams of calcium a day, that doesn't mean that you have to take 600 milligrams twice a day.It means that if you're getting two servings of dairy, which is 300 milligrams each, you'd take one 600 milligram pill a day.Calcium carbonate and calcium citrate are two of the popular and very effective supplements.Calcium citrate has less calcium per pill. You may have to take two pills to get 600, but it has the advantage you can take it with or without food.Calcium carbonate will give you 600 milligrams of calcium in one pill, but you really have to take it at a meal to get maximum absorption.
Ethel Siris, MD: Because of the way absorption of calcium works. You need stomach acid to absorb calcium in the form of calcium carbonate, and you make stomach acid when you eat.If you're a person on an anti-acid, on a proton pump inhibitor, or an H2 blocker because you have GERD, or you want to reduce acidity,some people would say that it's smarter to take calcium citrate if you're on one of those anti-acid type agents,but it's likely that if you take your calcium carbonate with food, you would still absorb it.