The build up of iron in the body can contribute to many types of cancer and vascular disease, a finding which calls into question whether vitamins fortified with iron are actually beneficial, according to a study led by Dartmouth Medical School professor Leo Zacharski. After 16 years of researching the risks of high iron levels, Zacharski and his team plan to publish their findings in a comprehensive paper this spring.
Because humans cannot properly excrete iron, excess amounts of the element can build up in the body over time, Zacharski said. Medical professionals have hypothesized for years that excess iron contributes to many ailments, he said. These ailments may include Alzheimer's disease, according to fellow DMS professor Barney Dwyer, whose study on the relationship between iron levels and Alzheimer's disease is currently in its early stages.
In the team's first study, the researchers measured levels of ferritin, an iron-storing protein, in 1,277 people. The subjects were divided into two groups -- a control group, whose ferritin levels were not changed, and a test group, who had blood drawn every six months over a six- year period ending in 2005 in order to lower their ferritin levels to the range of a healthy child.
"Kids are healthy," Zacharski said. "That's the healthiest time of life, and that healthiness is somehow related to this relatively low iron level."
Sixty of the 641 control patients developed malignancies during the trials, and 36 died of the cancer, Zacharski said. In the 636-person test group, though, malignancies developed in 38 patients, and only 14 died as a result of the ailment.
The risk of developing lung, prostate and colon cancer, compared to other forms of the disease, was especially reduced in the test group, according to a 2008 paper published by Zacharski in the Journal of the National Cancer Institute.
The growing tendency to take vitamin supplements is partially to blame for increased iron levels in adults, Zacharski said.
"The bottom line is, if a person isn't iron deficient, they should not take extra iron," he said. "Our bodies are not designed to handle excessive iron. We cannot excrete that. It just builds up and causes problems of aging."
Foods unnecessarily fortified with iron also contribute to high levels, Zacharski said.
"It's inappropriate to spray iron on the general population indiscriminately in hopes of saving someone here and there from iron deficiency," he said.
While most of the general public cannot have blood drawn every six months, Zacharski urged people to have their iron levels tested and to read food and drug labels more closely, citing the popular Flintstones' brand of children's vitamins as a potential risk.
"Flintstones are recommended for children as young as age four," he said. "Read the fine print, and it says this product has 18 milligrams of iron per pill. That is the daily iron requirement of a menstruating adult woman that you're giving to a 4-year-old."
Past studies on iron excesses in mice, whose bodies are capable of excreting iron, cannot be applied to humans, Dwyer said.
"Sometimes mice aren't the answer," he said. "If you're studying a disease of iron storage in an animal model that doesn't store iron, then there is some cause for concern."
Zacharski and Dwyer said they hope to use the concrete evidence in their work to alert the public about avoidable health risks.
"This is what science is supposed to be," Zacharski said.
