Just the Facts About Iron and How Much We Need

M.A., Health Writer

As fears about depleting the earth's resources abound, iron remains an abundant element, one that we're not set to run out of anytime soon. It is also a necessary mineral for us, supplied in the protein hemoglobin in our red blood cells — hemoglobin actually makes our blood red and also ferries oxygen from our lungs to the rest of our body. Without sufficient iron, the body comes up short on those cells.

Think of the body as environmentally friendly, because it actually recycles and conserves this mineral for us. Iron is a triple-tasker in our bodies, for in addition to oxygen transport, it also participates in deoxyribonucleic acid (DNA) synthesis — a biological process that creates the DNA molecule that carries our genetic information. Iron also plays a role in metabolism and energy production.

How much do we really know, and need to know, about iron? It's time for an iron primer with the expert help of Carol Haggans, R.D., and scientific and health communications consultant for the Office of Dietary Supplements at the National Institutes of Health. In a telephone interview with HealthCentral, Haggans helps us understand, among other topics, why we must have iron — and why we don't need too much of it.

Enough is enough

"Most people in the United States do get enough iron," Haggans says, "but certain groups can be lacking." Here's what she'd like you to know about some of those groups:

  • Infants: Healthy, full-term infants are generally born with enough iron for the first 4-6 months — breast milk is actually very low in iron. After that, they need good sources of iron from foods or iron-fortified infant formula. Premature babies may require an iron supplement. Talk to your pediatrician if you have specific questions about iron and your infant.
  • Young children: They can become iron deficient without getting enough iron from solid foods.
  • Premenopausal women: Women with unusually heavy bleeding, menorrhagia, can become iron deficient. It's estimated that 10 percent of menstruating women may have this condition.
  • Pregnant women: The amount of iron needed during pregnancy increases, so pregnant women may need to take a prenatal supplement that contains iron. Many of those contain 27 mg of iron, the recommended dietary allowance (RDA) for pregnant women.

"It's important for pregnant women to talk with their healthcare providers because emerging research indicates that some in the U.S. are already getting enough iron from foods, and getting excessive amounts of iron could also have detrimental effects,” Haggans says.

The upper limit for adults is 45 mg per day, unless you are under a doctor's care.

Answers about anemia

A person who doesn't get enough iron can develop iron-deficiency anemia, the type that makes up nearly one-half of all anemia cases.

"This can cause fatigue and lack of energy, developmental delays, gastrointestinal upset, poor memory and concentration, and reduced immunity," says Haggans. Although typically caused by low iron intake, it can be due to chronic bleeding from ulcers or intestinal polyps, for example.

Someone who's devoid of enough iron is likely low on other vitamins and minerals needed to produce hemoglobin. These include copper, vitamin B12, folate, vitamin B6, and riboflavin, and when reserves are short, the body can't make enough red blood cells.

Eat for iron

Just because you consume iron doesn't mean you "get" all of it, says a 2014 report in the Journal of Research in Medical Sciences. Humans typically absorb between 5 and 35 percent, depending upon their health and diet, and the type of iron.

  • Heme iron is contained in the animal proteins meat, poultry, and fish and is more easily absorbed, meaning bioavailable, and used by the body than...
  • Non-heme iron that occurs in plant sources and iron-fortified foods such as cereals and breads.

"People who eat a balanced diet with a variety of nutritious foods don't necessarily need supplements," Haggans says. Recommended daily amounts of iron are set at:

  • 8 mg: men or post-menopausal women
  • 18 mg: premenopausal women

"Those who are vegetarian need twice as much as others because of that lack of bioavailability," says Haggans.

If you're vegetarian

In fact, a 2016 study in The Permanente Journal found that iron-deficiency anemia is more common in vegetarians than non-vegetarians and recommends simply that the former group try to consume more iron. The authors say that can be accomplished by eating more:

  • Leafy greens and legumes
  • Soy products
  • Dark chocolate
  • Blackstrap molasses
  • Sesame seeds and tahini
  • Pumpkin seeds
  • Sunflower seeds
  • Raisins
  • Prunes
  • Cashews

They caution that iron absorption may be compromised by:

  • Phytates, antioxidant compounds found in whole grains, legumes, nuts and seeds. They "bind" to certain minerals, including iron.
  • Tannic acid in teas
  • Calcium in dairy
  • Fiber
  • Polyphenols in coffee and cocoa
  • "Spicy" spices, such as turmeric, coriander, chiles and tamarind

Do eat iron-rich foods with those foods containing lots of vitamin C, to help increase absorption of non-heme iron. Having a salad with tomatoes accomplishes just that, for example. Don't stress too much over this. Just keep in mind that when all is said and done, if you eat a wide variety of nutritious foods, you probably don’t have to worry too much about these enhancers and inhibitors of iron absorption, Haggans says.

"Chances are, you're doing just fine," she says. "But if you have questions about iron, ask your healthcare provider or a registered dietitian."

See more helpful articles:

Iron Deficiency Linked to Coronary Artery Disease Risk

Should You Stop Taking an Iron Supplement?