There are two major sources of iron in our food: heme iron in meat (especially liver), fish and poultry, and nonheme iron in legumes, grains, fruits and vegetables.
Iron from meat may lead to overdose as it is rapidly absorbed regardless of the body’s needs. Iron from plants, on the other hand, has no risk of overdose as it is absorbed according to the body’s needs.
Side effects of iron pills include constipation, nausea, vomiting, diarrhea, dark colored stools, abdominal distress, and increased oxidative stress from overdose. In children, death has occurred from ingesting 200mg of iron.
Those who should not take iron pills include postmenopausal women and people with hemochromatosis, which causes excessive absorption of iron, leading to a build-up of excess iron in organ tissues.