Iron is a mineral found in the human body as well as many other life forms on earth. Iron is one of the components of the proteins that transport oxygen, and is essential for regulating cell growth and performance. The amount of iron in your body is regulated by how well iron is absorbed in the intestines. Several factors affect iron absorption.
Dietary Iron
Dietary iron comes in two forms. Heme iron comes from hemoglobin, the protein in red blood cells that transports oxygen. Heme iron is only available from animal foods that once contained hemoglobin, such as red meat or poultry, and is efficiently absorbed from the intestines. Plant foods contain non-heme iron, which isn't absorbed as well as heme iron. Most dietary iron is actually from non-heme iron sources.
Drinks, Greens, Calcium and Phytates
If you drink coffee with a meal, you will decrease the amount of iron absorbed from your foods. The phosphates in cola drinks can also cut your iron absorption. Leafy green foods that contain oxalate and the tannins in tea decrease absorption, as does calcium. Both calcium supplements and calcium in foods have this inhibitory effect. Phytates, which are found in legumes and whole grains, also decrease absorption of non-heme iron. Some of the proteins in soybeans can inhibit non-heme iron absorption.
Phenols
Phenols and foods that contain them can strongly inhibit the absorption of iron. Phenolic acid is found in apples, peppermint and some herbal teas; all can decrease the amount of iron absorbed from a meal. Cocoa, spices, walnuts, and some berries, such as blackberries, raspberries and blueberries, can all inhibit iron absorption. Swedish cocoa, which is high in polyphenols, can decrease iron absorption by up to 90 percent, according to the Iron Disorders Institute.
Vegetarian Diets
According to the Office of Dietary Supplements, non-heme iron absorption varies from 2 to 20 percent for most people, which is low compared to the 15 to 35 percent absorption rate of heme iron from animal sources. Eggs, which may be a staple of an ovo-lacto vegetarian diet, contain a compound that decrease iron absorption. If you're a vegetarian and obtain much of your protein from soy products, your iron absorption can be negatively affected because so much of your iron is from non-heme plant sources and because soy can decrease non-heme iron absorption.
Medications and Iron Stores
Some medications can impair iron absorption. Antacids and proton pump inhibitors decrease stomach acids, which also decrease iron intake. The level of iron in your body can affect absorption; if your iron stores are high, you won't absorb as much iron. This is the body’s mechanism to protect you from getting so much iron in your system that you develop iron toxicity. In contrast, if your iron stores are low, your body will try to increase its absorption of iron.
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