Vitamin C & Iron Absorption

Iron is a metallic element which comprises about 5 percent of the mineral content of the earth's crust. Dr. Elson Haas, author of "Staying Healthy with Nutrition," believes that iron may have been the first mineral to be incorporated into living tissue, as it is found in all living things and in every cell in your body. Even though your body requires relatively small amounts of iron, it is one of 17 minerals that are deemed essential for human health.

Iron Functions

The primary function of iron in humans is the formation of hemoglobin, which is the oxygen-carrying protein found in your red blood cells. Iron accounts for the properties of myoglobin, a protein that transfers oxygen into muscle cells and increases their capacity to do work. Iron is an important part of many enzymes, including the cytochrome system of enzymes, which metabolize toxins in your liver and prevent oxidative damage to your cells. Iron also participates in cellular energy production and in immune function.

Dietary Iron

Iron is present in a wide array of plant and animal foods, including soybeans, legumes, greens, meats and whole grains. However, the iron in plant foods is typically present in a poorly-absorbed ferric, or non-heme, state. Ferric iron is an oxidized form of iron, which is stable in air and water. A form of iron that is more easily absorbed from your intestine, called ferrous or heme iron, is found in meats. Exposure to acid, such as stomach acid, converts some dietary ferric iron to ferrous iron, thus facilitating its absorption. A 2011 review in "Biochimica et Biophysica Acta" cites the importance of stomach acid in iron absorption, a relationship that was recognized 50 years ago among patients who had had parts of their stomachs surgically removed.

Vitamin C Enhances Iron Absorption

Like stomach acid, ascorbic acid, or vitamin C, helps to convert dietary ferric iron to the ferrous form. This effect was outlined in a 2004 review published in "International Journal for Vitamin and Nutrition Research," which suggested that ascorbic acid is the most efficient enhancer of non-heme iron absorption. A 2010 "Journal of Pediatric Gastroenterology and Nutrition" study showed that the ascorbic acid in orange juice improves absorption of an inexpensive iron supplement that is commonly administered to children.

Who Needs Iron?

According to Haas, healthy adult men typically do not require iron supplementation. They lose very little iron on a daily basis, and taking supplemental iron could actually lead to iron overload, which is associated with fatigue, weight loss, headaches and other neurological symptoms, heart rhythm abnormalities, joint pain, liver problems, impotence and thyroid abnormalities. Unlike men, growing children and women of childbearing age may not be able to acquire sufficient iron from their diet, and supplementation is often necessary to avoid iron deficiency.

Considerations and Dosages

Iron needs vary with age, gender and metabolic status, varying from a recommended dietary allowance of 7 mg for toddlers to 27 mg for pregnant women. Taking your iron with a glass of orange juice or a vitamin C supplement will enhance iron absorption. Your daily requirement for vitamin C also varies with age, ranging from 15 mg for children to 120 mg for lactating women, but many people safely take much larger doses. Ask your doctor if you need extra iron before you start taking a supplement.