Iron and calcium are two vitamins that are essential for good health. While iron is necessary for the formation of hemoglobin and subsequent transport of oxygen throughout the body, calcium is needed to help build strong bones and teeth as well as to maintain nerve function. Before you consume either of these vitamins, whether you choose to do so through whole foods or supplements, you should know how iron and calcium interact to optimize their nutritional benefits in your body.
Significance
Iron is a trace mineral that is essential for oxygen transport, metabolism, growth, healing and reproduction. Only a small amount of iron is necessary to fuel these processes---about 18 mg/day in adult females and 8 mg/day in adult males, the difference being the significant blood and subsequent iron losses in women during menstruation. Teenagers, women of child-bearing age and vegetarians are at greatest risk of iron deficiency, the most common nutritional deficiency worldwide, which can cause fatigue, disrupt memory and other mental functions, and increase the risk for preterm birth during pregnancy.
Types
The plant-based forms of iron, which are called nonheme, include foods such as cereals, breads and fruits. These are the most common forms of dietary iron, but they do not absorb in the body as well as their animal-based counterparts known as heme iron. Heme derives from the hemoglobin that transports oxygen throughout our bodies, and it absorbs two to three times better than nonheme sources. Examples of these iron-rich heme foods include red meat, eggs, poultry and tuna.
Expert Insight
The American Journal of Clinical Nutrition suggests that calcium consumption interferes with iron absorption. Calcium-rich foods like dairy products, beans, fortified juices and cereals, and dark leafy greens like kale, bok choy and cabbage, when eaten in combination with or around the same time as iron-rich foods, can decrease the total absorption of iron into the body. Data suggest that individuals should consume calcium no sooner than two hours after eating an iron-rich meal to prevent decreased iron absorption leading to iron deficiency.
Considerations
Combining heme with nonheme iron sources and/or foods rich in vitamin C in the same meal will significantly increase the total absorption of iron into the body. For example, a grilled chicken sandwich with sliced tomato and roasted bell pepper on a whole-wheat bun is a combination of both types of iron as well as vitamin C that will give you a well-absorbed boost of iron for the day. Just be sure to avoid consuming dairy products like milk or cheese within two hours of this iron-rich meal to optimize the total absorption of iron into your body.
Warning
Other chemicals and pharmaceuticals have also been found to inhibit iron absorption from nonheme food sources. Polyphenols and phytates found in coffee, tea, and whole grains as well as medicines like antacids, histamine receptor antagonists and proton pump inhibitors, which are commonly used to treat acid reflux and ulcers, can decrease iron absorption from plant-based foods. Iron supplements are often recommended for individuals being treated long-term with these medications, but always check with your doctor before starting a new vitamin regimen.
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