These minerals are incompatible. Magnesium can interfere with the body's ability to absorb iron, particularly if taken in large doses. To optimize absorption of both minerals, it's often suggested to take iron and magnesium at different times of the day. For instance, you could take one in the morning and the other in the evening. It's also important to note that certain foods, like those rich in vitamin C, can enhance iron absorption, while others like dairy products or caffeine can inhibit it.