What Percentage of Iron Has to Be in Your Body?

Iron is what makes blood red.

Iron is what makes blood red.

Iron is an essential mineral needed for strong bones and to make hemoglobin, the compound in blood that carries oxygen. Only a very small percentage of your body is comprised of iron, but without enough of it your blood can’t carry adequate amounts of oxygen to your tissues and anemia develops. If you have no energy, reduced strength and super-pale skin that looks like a vampire’s, it’s possible you need more iron in your diet. Consult with your doctor before taking iron supplements.

Percentage of Iron in Your Body

Iron is considered a micromineral, which means only trace amounts of it are needed by your body for healthy function. In contrast, calcium, phosphorus and magnesium are needed in much higher amounts each day. The amount of iron in the body of an average-sized woman is approximately 2.3 grams, which makes up only about 0.006 percent of her total mass. For comparison, calcium makes up about 1.4 percent of the mass of a human being. Men’s bodies contain a little more iron overall, but women have more proportionally given their smaller size.

Recommended Daily Amount

Iron is about the only nutrient than women need more of compared to men, at least in terms of amount per day. The reason, of course, is menstruation. Any type of blood loss significantly reduces the amount of iron in your body, because about 70 percent of it circulates in your blood as hemoglobin. The rest is mainly within your bones, although some is found in muscle tissue. The recommended daily amount of iron for menstruating women is about 18 milligrams, but the requirement increases to 27 milligrams during pregnancy. Blood lost due to injuries or internal ulcers -- of the stomach or intestines -- also increases the need for iron.

Good Sources

Foods rich in iron include virtually all red meats, especially beef liver and heart. Other good sources include poultry, fish, soybeans, wheat, pumpkin seeds, spinach, kidney beans, broccoli and lentils. Fortified cereals are excellent sources, too. In order to properly absorb and use dietary iron, you also need to consume enough vitamin C and vitamin A. Drinking coffee or black tea decreases iron absorption due to the presence of tannins, whereas the phytates in some legumes can have the same negative effect.

Types Within Food

Not all dietary iron is the same. The two main forms are called heme and non-heme, with heme iron absorbed much better by the body. Meat products contain up to 40 percent heme iron, whereas all of the iron in plant foods is non-heme. Only about 3 percent of non-heme iron is absorbed, which partially explains why vegetarians are at much greater risk of iron deficiency and anemia. On the other hand, supplementing with iron should be under the supervision of your doctor because too much is toxic and can lead to nausea and diarrhea.

 

References

  • Human Physiology: An Integrated Approach; Dee Silverthorn and William Ober
  • Textbook of Nutritional Medicine; Melvyn Werbach and Jeffery Moss
  • The Nutribase Complete Book of Food Counts; Art Ulene
  • Encyclopedia of Human Nutrition; Benjamin Caballero et al.

About the Author

Sirah Dubois is currently a PhD student in food science after having completed her master's degree in nutrition at the University of Alberta. She has worked in private practice as a dietitian in Edmonton, Canada and her nutrition-related articles have appeared in The Edmonton Journal newspaper.

Photo Credits

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