Iron: are we getting too much?

"I feel like the luckiest guy alive," says Nutrition Action subscriber Davis "Doc" Ball, 57, of San Antonio, Texas. "I had no idea how sick I was until last June, when my doctor happened to notice something unusual on a routine blood test."

The doctor's discovery: Ball's blood was loaded with more than enough iron to kill him.

As it turns out, "Doc" is one of the estimated one million Americans who suffer from iron overload, or hemochromatosis.

For most adult males and postmenopausal women, getting enough iron isn't a problem. It's everywhere - in meat, enriched-flour breads and pastas, fortified breakfast cereals, and most multivitamins.

But getting too much can mean trouble for people with iron overload, like "Doc" Ball. And now some researchers are saying that iron may be linked to cancer and heart disease So far, though, the evidence is skimpy.

HEMOCHROMATOSIS

For most people, hemochromatosis [HEE-mow-CROW-muh-TOW-sis] comes down to a flip of the genetic coin. If you happened to inherit two hemochromatosis genes, one from your mother and one from your father, you've got it.

"About one out of every 250 Americans does, which makes it the most common genetic illness among whites," says iron expert Eugene Weinberg of Indiana University.

Men who have the disease are more likely to feel its effects than women, possibly because they don't spend 30-some-odd years regularly losing iron during menstruation.

"People with hemochromatosis absorb about twice as much iron from their food and supplements as other people do," says Weinberg. The extra iron is stored in the liver, pancreas, heart, and brain. For four or more decades, our bodies can bear the overload without discomfort or irreparable damage.

"But eventually, usually in men after age 50, the iron starts to damage the liver and other organs," says expert Bruce Bacon of the St. Louis University School of Medicine.

"If patients are early in the disease," he explains, "they may feel fine. Later on, they may complain of fatigue, impotence, or symptoms of diabetes like persistent thirst or the need to urinate frequently."

If it's caught soon enough, the damage can be prevented. A simple blood test can tell your doctor if you're at risk (see "What to Do").

"Treatment consists of removing excess iron from the body," says Weinberg. That means regular blood "donations" (they're donated to the trash bin, since most blood banks won't accept blood from people with hemochromatosis).

But if you're not one of the million Americans with the disease, do you still have to worry about iron?

CANCER

Rats exposed to a chemical that causes breast cancer develop one-third more tumors when they are also given ten times their normal iron ration.(1)

When it comes to humans, though, "the body of evidence is small," acknowledges researcher Richard Stevens of the Pacific Northwest Laboratory in Richland, Washington.

In one study, Richard Nelson and his colleagues at the University of Illinois College of Medicine at Chicago looked at the blood ferritin levels of 304 men and women whose colons had been examined as part of another study. (Ferritin is the form iron takes when it's stored in the body.)

Those with the most ferritin were more than four times as likely to have adenomas (benign polyps) as those with the least ferritin.(2) Adenomas often turn into colon cancer.

That jibed with the results of a similar study by Richard Stevens. Among 198 Taiwanese government workers those who died of liver cancer had significantly higher ferritin levels before they were diagnosed than those who remained cancer-free.(3)

But that's not the same as proving that too much iron causes cancer. "There's just not enough research yet to reach a conclusion about the role of iron in human cancer," says Alberto Ascherio of the Harvard School of Public Health.

HEART DISEASE

Researchers don't know exactly why arteries sometimes start to clog.

One theory holds that the process begins when LDL ("bad") cholesterol becomes oxidized - when it combines with oxygen. And, at least in test tubes concentrations of iron can trigger LDL oxidation. Could too much iron in our blood do the same thing?

That possibility received some support in 1992, when Jukka T. Salonen and his colleagues reported that among 2,000 middle-aged Finnish men, those with high levels of ferritin were more than twice as likely to suffer heart attacks as those with low levels.(4)

But since then, three out of the four studies that measured ferritin failed to find any connection with clogged arteries.

"It's an interesting hypothesis, and we should do a better job of studying and keeping an eye on it," says iron expert Ray Yip of the Centers for Disease Control (CDC) in Atlanta. "But it's not strong enough yet to act on."

Who Needs Extra Iron?

While most Americans get enough iron - and some get too much - others may be deficient:

* Youngsters. Toddlers, children, and adolescents, who are still growing, often need more iron than they get. According to the latest surveys, three to six percent of U.S. children and adolescents are iron-deficient.

* Pregnant & breastfeeding women. The demand of a growing fetus or infant for iron may exhaust the mother's reserves. But not all pregnant or breastfeeding women need extra iron.(1) Check with your doctor.

* Adults with iron-deficiency. It's the most common nutrient deficiency. An estimated four percent of white women, six percent of African-American women, and eight percent of Latino women are iron-deficient (only two percent of men are). Poor diet is often - but not always - at fault. "Loss of blood, from heavy menstrual losses or gastrointestinal bleeding from ulcers or cancer, for example, can also cause a deficiency," says iron expert Ray Yip of the Centers for Disease Control (CDC).

Iron in Food

How much iron should you get from your diet? If you rely from the numbers on food labels, you could end up with far more than you need. The problem: labels list iron as a percentage of the Daily Value (%DV). But the DV is based on the U.S. Recommended Daily Allowances (USRDAs), which haven't been updated since 1968.

The Daily Value for iron is 18 milligrams (mg). But unless you're pregnant, that overestimates the amount of iron you need. Here are the current recommendations:

* 10 mg a day for children, men over 18, and women over 50,

* 12 mg a day for males aged 11 to 18,

* 15 mg a day for females aged 11 to 50 and for lactating women, and

* 30 mg a day for pregnant women.

So if you're a postmenopausal woman, a man, or a child under 11, a food with "10% of the DV" for iron, for example really contains closer to 20 percent of your quota, How to solve the problem? Double the "%DV" for iron that appears on food labels.

What foods give you the most iron? Almost 30 percent of the iron in the average American's diet comes from just two. Beef is the biggest source, and its iron (like much of the iron in meat, poultry, and fish) is better absorbed by our bodies than the iron in vegetables, grains, and other plant foods. Bread, rolls, and crackers are next, simply because we eat so much of them.

Some other sources: beans, cold or hot fortified cereals, clams, oysters, pork, poultry, shrimp, spinach, and tofu.

ALL ADULTS

* Get tested. "Every adult should know his or her iron status," says Bruce Bacon of the St. Louis University School of Medicine. At your next check-up, get either your blood ferritin or your blood transferrin saturation checked.

"A ferritin level above 200 could be a sign of excessive iron storage," says Bacon. With transferrin saturation, "30 percent is normal, and 50 percent or more merits further tests." Most people with 62 percent saturation or more have hemochromatosis.

MEN & POSTMENOPAUSAL WOMEN

Even if your iron reserves are normal, many experts recommend that you avoid getting more than you need.

* Check your medicine chest. "Don't take iron supplements," says the CDC's Ray Yip, "unless you have been told to by a health professional who is familiar with the risks of taking iron."

If you take a multivitamin, look for one that's iron-free (see cover story, November 1995). If that's hard to find, try one with no more than 50 percent of the U.S. Recommended Daily Allowance (USRDA) for iron. Most have 100 percent. "The smaller the amount of iron, the better," says iron expert James Cook of the University of Kansas.

* Donate blood. Consider doing it regularly. It's not only a public service, it's the only safe way to lower your iron stores.

* Don't panic. If the iron level in your blood is normal, continue to eat your good diet. Don't substitute a lousy low-iron food for a healthier higher-iron one.

(1) Journal of the American Medical Association 270: 2846, 1993.

(1) Carcinogenesis 15: 1567, 1994. (2) Journal of the National Cancer Institute 86: 455, 1994. (3) Journal of the National Cancer Institute 76: 605, 1986. (4) Circulation 86: 803, 1992.