Too Much—and Too Little—of This Nutrient May Increase Your Colon Cancer Risk, Studies Show

Ashley Broadwater

Wed, March 19, 2025 at 1:41 PM UTC

6 min read

Too Much—and Too Little—of This Nutrient May Increase Your Colon Cancer Risk, Studies Show

Having too much or too little iron can increase the risk of colon cancer, as iron is essential for red blood cells and immune system function.
Iron deficiency can lead to the immune system being unable to detect and destroy cancer cells, while excess iron can increase the risk of colon cancer due to its effect on tumor cell proliferation.
The National Institutes of Health recommends different daily iron intake levels based on age, gender, and pregnancy status, with iron-rich foods being the preferred source over supplements.

Nowadays, it seems like just about anything can lead to cancer — microplastics in pans, sitting for hours on the couch and the literal sun , to name a few, can all up your risk.

Some snake oil salesmen and alternative health gurus like to stoke the fear of cancer to sell a product or claim they have found a way to a miracle cure, but let's be real: If decades of scientific research from the world's leading experts have yet to find a way to cure cancer, it's unlikely your grandma's apple cider vinegar drink will make a difference.

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This doesn't mean all hope is lost. Studies searching for ways to prevent cancer , especially colon cancer , have found ways people can avoid increasing their cancer risk.

One nutrient gained a lot of attention because of its connection to cancer, and having either too much or too little of it may up your risk of colon cancer specifically.

The Nutrient Linked to Colon Cancer Risk

Having too much or t oo little iron increases the chances of colon cancer, according to studies.

Iron is essential to red blood cells, which supply oxygen to the body, says Dr. James Cox, MD , a gastroenterologist and assistant professor at Burnett School of Medicine at Texas Christian University. It also helps to keep the immune system in top shape, which is why doctors think iron deficiency and overload is connected to cancers like colon cancer.

Iron helps with immune cell growth and activity . It also can affect the activation of different immune responses in B cells.

Signs of iron overload include fatigue, an irregular heartbeat , joint pain and stomach pain. Signs of an iron deficiency are similar but also involve pale or yellow skin, chills and hair loss.

Relationship Between Iron and Colon Cancer

Iron deficiency and colon cancer

When you don't have enough iron, the immune system isn't able to optimally provide surveillance for the body—allowing cancer cells to remain hidden and grow at uncontrollable rates. Being iron-deficient also disrupts the process of inducing cell death , which is key to stopping abnormal cells before they grow into tumors.

"The immune system cannot effectively detect nor destroy cancer cells [if you have an iron deficiency]," says Dr. Michelle Hughes, MD , assistant professor of medicine at Yale School of Medicine. "This allows cancer cells to grow and spread more rapidly."

Having anemia from iron deficiency has been a characteristic observed in people diagnosed with colorectal cancer, especially among those with right-sided tumors . That study also found iron deficiency linked to lymphatic invasion, when cancer cells are present in the blood vessels.

Not getting enough iron in your diet also leaves you susceptible to infections and diseases. Some viruses , for example, hijack a cell's genes and the changes in cellular processes could potentially push cells into becoming unstable. So far, research has found some possible evidence of a connection between Epstein-Barr virus, human papillomavirus and John Cunningham virus.

Iron overload and colon cancer

On the other end, consuming too much iron also raises your risk of cancer. "Excess iron can increase the risk of colon cancer due to its effect on the tumor cell proliferation," Cox explains. "Whether excess iron increases the actual risk of colon cancer [as a whole] is unknown." Research has found an association between high serum ferritin—a protein that stores iron—and an increased risk of early-stage colorectal cancer.

From what researchers currently know, it seems like excess iron is creating free radicals , unstable molecules that can damage the DNA of nearby cells. DNA changes increases the risk for genetic mutations and developing cancerous cells. Dr. Anne Mongiu, MD, Ph.D , a colorectal surgeon and assistant professor in the department of surgery at Yale School of Medicine says DNA damage, lipid peroxidation (when free radicals attack fatty acids used in a cell's outer barrier) and protein damage are only a few examples of what having too-high iron levels can do to the body.

Abnormally high iron levels may also fuel tumor growth by making people susceptible to infections that can progress to cancer.

How Much Iron Should People Try to Consume?

If having too much and too little iron is bad for colon cancer risk, how much iron should you get? The National Institutes of Health recommends the following:

Men ages 19 to 50 years old: 8 milligrams (mg) a day
Women ages 19-50 years: 18 mg a day
People 51 years and older: 8 mg a day
When pregnant: 27 mg a day
When lactating: 9 mg a day

Keep in mind, however, that these are general guidelines. Every body is different so there's other factors that affect iron needs.

"The amount of iron people should get varies by several factors, including age, menstruation, pregnancy status and dietary patterns," Mongiu notes. Cox also recommends 18 mg of iron a day if you're premenopausal and 8 mg a day if you're postmenopausal . Additionally, other medical conditions may require different iron amounts.

Does this mean people should stock up on iron supplements? Ideally, doctors would want you to grab your iron from food. Iron-rich foods include leafy greens, fish, eggs, chicken, wheat products, raisins and cashews, to name a few.

"Iron supplements are not necessary for most, but could be considered after discussion with a medical provider if a person is not getting enough routinely or if there are low iron stores that need to be repleted," says Mongiu.

Your best bet, per usual, is to talk to your healthcare provider or a dietitian. And to add some leafy greens to your plate for dinner tonight.

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Sources

Dr. James Cox, MD , gastroenterologist and assistant professor at Burnett School of Medicine at Texas Christian University
"Iron Metabolism and Immune Regulation." Frontiers in Immunology .
"Hemochromatosis (Iron Overload)." Cleveland Clinic .
"6 Signs You May Be Iron-Deficient." Cleveland Clinic .
"Flipside of the Coin: Iron Deficiency and Colorectal Cancer." Frontiers in Immunology .
Dr. Michelle Hughes, MD , assistant professor of medicine at Yale School of Medicine
"Absolute and Functional Iron Deficiency in Colon Cancer: A Cohort Study." Medicina .
"Viruses in colorectal cancer." Molecular Onoclogy .
"Serum ferritin and the risk of early-onset colorectal cancer." World Journal of Gastrointestinal Oncology .
"Iron in Cancer: Ironing Out the Intricacies." American Association for Cancer Research .
Dr. Anne Mongiu, MD, Ph.D , colorectal surgeon and assistant professor in the department of surgery at Yale School of Medicine
"Iron imbalance in cancer: Intersection of deficiency and overload." Cancer Medicine .
"Iron." National Institutes of Health .
"52 Foods High in Iron." Cleveland Clinic .