Iron is found in a variety of foods and available as a supplement. It’s a part of hemoglobin, a protein that transports oxygen throughout your body. You also need this essential mineral for energy production. You store extra iron throughout your body rather than excrete it. The Office of Dietary Supplements reports that it’s extremely rare to get too much iron through diet alone. Always consult with your physician before taking an iron supplement. It's normal for supplements to darken your stool, but excessive iron can produce a range side effects, including some severe ones.
Digestive problems are the most common consequence of iron toxicity. The Office of Dietary Supplements states that acute ingestion of 20 milligrams per kilogram of body weight -- 1,360 milligrams for a 150-pound person -- of iron can cause an upset stomach, constipation, nausea, stomach pain, vomiting and feeling faint. These symptoms will typically appear within six hours after taking an iron supplement. Minimize your risk by eating a snack or meal with your iron pill.
If your initial iron overload symptoms are severe, you are likely to progress to more moderate and severe complications. Within 12 to 48 hours, you may experience shock, fever, convulsions and bleeding disorders. After two to five days, you can develop jaundice, a yellowing of the skin, low blood sugar and liver failure. The final, most severe stage can result in intestinal obstruction, coma, organ failure and even death. Severe symptoms can result after taking more than 60 milligrams per kilogram of iron at once.
According to the Office of Dietary Supplements, ingesting 25 milligrams of iron can decrease the amount of zinc you absorb. Symptoms of a zinc deficiency include growth problems, loss of appetite and decreased immune functioning. In more severe cases, you may experience hair loss, diarrhea, eye and skin lesions and the inability to heal wounds. The University of Maryland Medical Center states there is some evidence linking elevated iron levels to heart disease, breast cancer and Alzheimer’s disease, but the research is not definitive. Individuals with inflammatory bowel disease also show increased iron stores in the parts of their intestines that are inflamed.
Recommendations and Considerations
The recommended dietary allowance of iron for men 19 to 50 years is 8 milligrams per day, and for females in that age range the RDA is 18 milligrams. For both sexes over 50, the RDA is set at 8 milligrams. Iron toxicity is most likely to occur in people with hemochromatosis, a disease characterized by disproportionate buildup of iron due to a gene mutation. It is extremely rare to overdose on iron from dietary sources alone. The tolerable upper intake level is set at 45 milligrams. Keep iron supplements away from children because iron is the most prevalent form of accidental poisoning in youth.