Can a high iron diet lead to certain forms of disease?
Is there be a link between the amount of iron in your diet and heart disease, diabetes, arthritis and certain forms of cancer? Scientists have been looking into this subject and their findings are surprising. Recent studies have turned our thinking and recommendations completely around when it comes to iron supplementation and dietary intake.
Theories about the iron link came about because of the disease hemochromatosis pronounced he-mo-kro-ma-to-sis. It is an inherited disorder in which too much iron accumulates in the body leading to diabetes, congestive heart failure, cancer, arthritis, loss of sexual desire and liver failure. Although few people have heard of hemochromatosis, this disease affects about one in 250 Americans.
The Ferritin Connection
The best test to determine how much iron you have stored in your body is a ferritin level, a simple test your doctor can perform. Ferritin is an iron-storing protein and represents the amount of iron stored in the liver, spleen and bone marrow. One unit of ferritin equals approximately 10 milligrams (mg) of stored iron. 28 For example, a serum ferritin level of 100 units indicates a total iron content of approximately 1,000 mg.
Cultures that have levels of iron between 100 mg to 400 mg of iron have virtually no heart disease. With levels greater than 800 mg we start to see increase incidence of heart disease. Iron plus oxygen causes the oxidation of cholesterol. This leads to plaque formation, which causes heart attacks and strokes. A good analogy would be rust formation inside pipes.
A Finnish study, published in the American Heart Association scientific Circulation 1, concluded that iron ranks second only to cigarette smoking as a risk factor for heart attacks and heart disease. It looked at ferritin levels in 1900 men in Finland ages 42 to 60. After five years, analysis showed that men who had more than 200 micrograms of ferritin per liter of blood were more than twice as likely to have heart attacks than men whose levels were below 200. The heart attack risk increases by four times in men who also have high levels of low density lipoprotein (LDL) cholesterol. Normal ferritin levels range from 100 to 150 micrograms in men and 50 to 100 micrograms in women.
If you have an elevated ferritin level your doctor will order a series of blood test including Total Iron Binding Capacity (TIBC) also expressed in micrograms per liter. Normal is around 33 percent. A reading greater than 62 percent for men and greater than 50 percent for women makes the diagnosis of hemochromatosis. If you have results between 40 and 60 percent you may have inherited one of the genes for hemochromatosis and may pass this onto your children.
Major causes of iron overload include excess animal products in the diet, multiple blood transfusions, cooking in iron pots and chronic ingestion of iron by supplementation. Some people continue to take iron pills for ten, 20 or even 50 years, because they were once told that they were anemic.
Iron & Industry
In the 1960s the makers of Geritol decided it would market its product to people who felt fatigued and tired. Geritol contains few vitamins and a lot of iron. Their marketing lead the American public to equate fatigue with anemia and the way to correct this was to take iron supplements. However, they had no scientific evidence to back their claims. In 1965, the Federal Trade Commission issued a cease-and-desist order to prevent the company from airing their commercials because of deceptive advertising. However, the Geritol people continued to advertise that their product would make you less tired and fatigue. Finally, in 1970 the Justice Department charged the makers of Geritol with violation of the Federal Trade Commission orders to stop deceptive advertising.
Common Iron Myths
- The number one nutritional problem in the United States is iron deficiency.
- Most women need more iron than they are getting from their diets.
- People over 50 do not get enough iron.
- You will become anemic if you don’t eat red meat.
- Liver should be eaten if you think you are anemic.
Studies show that close to 50 percent of adults in the United States (adult men and post menopausal women) have too much iron in their bodies. We’ve placed too much emphasis on iron deficiency anemia in this country, which is actually a rare phenomenon except in pregnant women and children that live in extreme poverty.
Women and Heart Disease
For years physicians have tried to explain why women have less heart disease than men, until they reach menopause (see fig-1). Most of their attention has focused on the female hormone called estrogen. When women reach menopause, they secrete lower amounts of estrogen and this was thought to be linked with the higher incidence of heart disease in older women.
A study that followed heart disease incidents in 4000 residents of Birmingham, Massachusetts, may prove this theory wrong. Researchers found an increased risk of heart disease in women within two years after menopause. The key result, however, involved the comparison of heart disease rates in two subgroups of women who had hysterectomies. One group had the removal of the uterus without the removal of the estrogen producing ovaries and the other group had both the uterus and ovaries removed. With the estrogen protection theory, one would expect the women who had the ovaries removed to have higher heart attack rates. However, both groups had a similar increase in risks compared to premenopausal women. It was the removal of the uterus that stripped women of their natural protection. It is theorized that without a uterus there is no monthly blood loss through menstruation and iron levels build up.
It was Dr. Jerome Sullivan, a researcher at the University of South Carolina and an expert in iron-heart diseases who first proposed that the protection exhibited by premenopausal women might be due to their lower iron levels prior to menopause when compared to men. Women have less iron stores because they lose iron each month during their menstrual cycle. Men, 20 to 40 years old, have roughly four times the amount of iron and four times the amount of heart attacks as women. As women reach menopause, age 45 to 50, and begin to accumulate iron, the male-to-female ratio of stored iron is about equal and so is the heart attack ratio. This data establishes iron as a new potential risk factor for heart disease. Oral Contraceptives
Numerous studies have also shown that prolonged use of oral contraceptives significantly increases a woman’s risk of heart disease. However, they have not been able to explain why. The iron/heart link now provides the answer. Oral contraceptives decrease menstrual blood flow in most women to a third or half of the normal rate. Therefore, women who use oral contraceptives are more likely to build up their iron stores early in life. This has been confirmed in a recent study conducted at the University of California 7 at Berkeley. It showed the amount of stored iron in women who had been using oral contraceptives for two years or more is roughly double that of non-users.
Vegetarians have lower risk
The public has been mis-lead for years that a vegetarian diet will cause iron deficiency or anemia. This theory been disproved time and again. Many studies of vegetarian diets have shown that the iron content of these individuals is well within the normal range.
The biggest contributor of iron in the diet is meat. This is another reason why cultures who do not consume a lot of animal products have not only low cholesterol levels but low iron levels as well. Countries whose diets are based on animal protein–such as the United States, Great Britain and Canada–have much higher iron blood levels versus countries whose diets are based on vegetable proteins–such as China, India and certain parts of Africa.
An ongoing study 12 in China of 6,500 people has revealed that these people have a significantly lower rate of heart disease and colon cancer than Americans. The answer is related to the Chinese diet, which is based on vegetable proteins. Only 7 percent of the Chinese diet comes from animal products. The cholesterol and iron levels of these individuals are far less than those of Americans.
Greenland Eskimos have a lower rate of heart disease then the general United States population. It has been suggested that Omega 3 fatty acids, known as Eicosapentaenoic Acid (EPA), may be the significant factor in the reduction of heart disease. Fish causes a thinning of the blood by reducing certain clotting factors. With reduction of certain clotting factors one may get tiny amounts of bleeding in the stomach and the rest of the gastrointestinal tract when fish is eaten. With small amounts of blood loss on a regular basis one also has loss of iron and it may be the loss of iron from the body that decreases the incidence of heart disease in Greenland Eskimos.
Dr. Randall Lauffer, a Harvard University biochemist and author of Iron Balance, 2 states that 20 to 30 percent of the iron in beef, poultry and seafood is absorbed by the body–compared to 3 to 5 percent of the iron from vegetables. One can see how easy it is to accumulate iron in the body by eating red meat and liver.
Another study to support this theory shows that Seventh Day Adventist men have 40 to 50% fewer heart attacks than non-Adventist men. 10 Adventist do not eat meat, but still consume large amounts of dairy products thus, their cholesterol levels are only slightly lower than the general population and do not account for the significantly lower rates of heart diseases. Since these men do not eat red meat, however they have lower levels of iron in their blood 11 than the general population thus explaining their lower rate of heart disease.
Iron and Other Diseases
A new explanation of why a high-fiber diet protects against colon cancer has been offered by Dr. Ernest Graf of the Pillsbury company and Dr. John Eden of the University of Minnesota. 14 They proposed that it is not the fiber that’s protective but rather a substance in the fiber. They focused on phytic acid, a phosphorus rich substance abundant in legumes, whole wheat, bran and rye. Phytic acid binds with iron in the intestinal tract and reduces the amount of iron available. 15 Studies dating back to the 1940s show that people who eat foods rich in phytic acid absorbed less iron than those who did not.
Studies also reveal an increase rate of other forms of cancer in people with high iron content 21, 22, 23. Iron plus oxygen in the body causes free radical formation. Free radicals are the formation of unstable atoms that cause DNA damage. Therefore, we get mutations of our genetic code, which leads to cancer formation. One study conducted in 1989 on 14,000 adults showed that men who had elevated iron levels were 37 percent more likely to obtain cancer of the lung, bladder, colon and esophagus.
Excessive iron in the body may cause damage to the insulin-producing cells in the pancreas. Iron may also lead to diabetes by causing liver damage.
Other studies have shown iron is deposited in the joints of the body, causing calcium deposits that lead to inflammation, stiffness and pain. Therefore, if you have arthritis you should not increase the iron in your diet.
Ways to Control Iron Intake
Milling of grains removes the phytic acid. That’s why breads made from non-milled grains are the best for you. White bread has five to 20 times less phytic acid than whole grain bread. In this country we not only make the mistake of removing the phytic acid from the grain but also we add iron to the product.
Iron pots leach iron into your food increasing your body’s iron content. Experts are now recommending you throw away your iron pots and cook in some of the new alternative non-stick products. This is one source of iron we can do without.
Studies have also found that vitamin C enhances the absorption of iron from the gastrointestinal tract 18. Therefore, do not eat foods rich in vitamin C at the same time with foods that are rich in iron. Try taking vitamin C supplements between meals to minimize iron absorption.
Coffee and Tea
It has also been shown that coffee and tea can reduce the amount of iron absorbed from foods. 13 They contain tannic acid, a chemical that inhibits the amount of iron absorbed.
A number of studies have shown that heavy alcohol consumption leads to high iron levels in the body. 19, 20 Alcohol increases the acidity of the intestinal tract and increases absorption of iron into the body.
Exercise has also been shown to reduce heart disease. Vigorous exercise leads to an increase of iron lost through various means. 25, 26, 27 Research has revealed that competitive athletes have lower iron levels.
There are three mechanisms proposed for the increase iron loss in athletes
- Increased loss of hemoglobin iron in the stools after a competitive sporting event. This may be due to the constant jarring of the intestinal organs during exercise and may even be related to the lack of oxygen to the intestines. The majority of oxygen must go to the heart, lungs and muscles during high intensive exercise.
- Exercise may cause loss of hemoglobin in the urine
- Much of the iron that is lost maybe do to loss of iron in the form of sweat
Aspirin has been effective in preventing heart attacks and colon cancer. It is thought to thin the blood by reducing the formation of blood clots that trigger heart attacks. However, aspirin’s effect could also be due to reductions in iron stores. Because it irritates the stomach, significant amounts of blood are lost through the stomach and into the bowel with each aspirin. This blood loss means iron loss as well.
Blood Donations and Treatments
Donating blood on a regular basis removes the toxic metal iron from your blood and thereby reduces your risk of heart disease, diabetes, arthritis and certain forms of cancer. People who donate blood on a regular basis have lower iron levels than non-donors. It is the treatment of choice in patients who have the hereditary form of hemochromatosis, mentioned earlier.