Is there an issue if you take iron and calcium together?

Although the mechanism by which calcium inhibits intestinal absorption of iron remains unclear, the threshold at which interference begins is approximately 300 mg of calcium. Most calcium supplements contain significantly more than this amount. read more

If you consume both calcium and iron (ferrous form) at the same time, they will be competing with each other for uptake by the transporter! Thus decreasing the absorption efficiency of both. This is typically a bigger issue for individuals taking either a calcium or iron supplement (or both) and not the average person consuming a balanced diet. read more

If you take additional iron at another time and so you don’t care if you don’t absorb the iron in your multi, then you can go ahead and take it with your calcium. Take your iron with vitamin C for best absorption. The ratio is 200 mg C to every 30 mg iron. That’s 30 mg elemental iron, so if you take 325 mg ferrous sulfate, for example, you’re only getting 65 mg elemental iron, so you’d need 400 mg vitamin C (but carbonyl iron is absorbed better than ferrous sulfate). read more