How Much Iron Supplement Should a Woman Take?

According to the World Health Organization, iron deficiency is prevalent in both industrialized and developing countries. "Iron deficiency affects more people than any other condition, constituting a public health condition of epidemic proportions," reads a WHO statement on iron deficiency. The Centers for Disease Control, in making recommendations to prevent and control iron deficiency, cites U.S. Department of Agriculture statistics showing that fewer than 30 percent of American women ages 12 through 49 get adequate amounts of iron.

Recommended Dietary Allowances

• The National Institutes of Health notes that healthy women during their childbearing years have the highest need for iron because menstruation and pregnancy reduce the body's stores of iron. RDA guidelines for women during these years are: 15 milligrams (mg) per day for ages 14 to 18; 18 mg/day for ages 19 to 50; 27 mg/day during pregnancy; 10 mg/day during lactation if the woman is 14 to 18; and 9 mg/day during lactation for women 19 to 50. Additionally, women with renal failure and gastrointestinal disorders that affect absorption of iron may require extra iron to prevent deficiency.

Iron in the diet

• Two types of iron are available in foods: Iron derived from animal food sources, called "heme iron," and iron derived from vegetarian food sources, called "non-heme iron." Non-heme iron is less readily absorbed, so vegetarians may need to consume nearly double the RDA in order to avoid iron deficiency, NIH points out. NIH recommends vegetarians combine citrus foods with iron sources because Vitamin C enhances absorption of non-heme iron.

Deficiency and anemia

• Widely-cited Cornell University studies show that women with iron deficiencies not severe enough to qualify as anemia still suffer negative consequences from insufficient iron. Their endurance of exercise and physical work is reduced, and if they exercise to be physically fit, they get less benefit from that exercise. Jere Haas, professor of maternal and child nutrition in the Division of Nutritional Sciences at Cornell University in New York, studies the functional consequences of mild to moderate iron deficiency worldwide. "Iron deficiency anemia in women of reproductive age is probably 3 to 4 percent of the population, but iron deficiency without anemia is another 10 to 12 percent," Haas said of women in the U.S. "We consider them to be at risk," Haas said of the second group.

Iron absorption fluctuates

• Too much iron can be a problem in itself. Therapeutic doses of iron supplements, for example, can cause unpleasant problems including constipation, diarrhea, nausea, vomiting, dark colored stools and abdominal distress. Haas pointed to statistics that show about 25 percent of American women take iron supplements. "That would be kind of a last resort. If you can get your nutrients from food you are much better off," Haas said. Iron in the diet is safer because of the way the body works, Haas noted. "The body in its infinite wisdom regulates how much iron it can absorb," he said. If the body has plenty of stored iron, it cuts back absorption of iron in the food. But if the body is running short, the reverse happens. "Women who are iron-deficient will ramp up their absorption of the iron in their diet," Haas said.

Getting enough iron in the diet

• Haas said a little planning and discipline is needed to consume enough iron, particularly for vegetarians who consume only non-heme iron. "Almost any flesh food is going to have a sufficient amount of iron in a small serving. And more important, it's going to be iron in a heme form, which is better absorbed," Haas said. "The other thing to keep in mind in the United States is that a lot of our food is already fortified with iron." Theoretically, getting enough dietary iron in the U.S. would be easy, Haas noted. "For some reason women are not getting a sufficient amount," he said. Several factors, such as income and lifestyle choices, influence diet and nutrition. "It's not difficult to eat a poor diet when you have limited income or poor eating habits," Haas said. Haas added there is a strong relationship between obesity and iron deficiency, because of high-calorie, high-fat, low-iron food choices. He recommended that people read nutritional labels on foods and learn about proper diet through books and Web sites. "If you're not diagnosed as anemic, don't think that you don't have a potential problem with iron," Haas said.