Although iron supplementation is necessary for millions of people who suffer from conditions like iron-deficiency anemia, evidence has revealed that it may come with a long list of side effects.

Nguyen M, Tadi P. Iron Supplementation. In: StatPearls. July 3, 2023.

Some people develop gastrointestinal issues since iron can impact the gut microbiome and trigger intestinal inflammation, research shows.

Shearer J, Shah S, MacInnis MJ, et al. Dose-Responsive Effects of Iron Supplementation on the Gut Microbiota in Middle-Aged Women. Nutrients. 2024;16(6):786.

Iron supplements “can cause either diarrhea or constipation and can make people feel like they are gassy,” says Daniel Landau, MD, an oncologist, hematologist, and contributor to The Mesothelioma Center at Asbestos.com.

In the future, biomarker tests could help identify patients who are at greater risk of developing iron-related colon cancer. “A biomarker test could look for genetic mutations or inflammatory markers linked to iron overload and cancer risk,” Adam L. Booth, MD, FCAP, Assistant Professor of Pathology and Immunology at Washington University School of Medicine, says.

For example, he adds, a test could detect genetic variations related to iron metabolism, which could signal that someone is more susceptible to certain cancers. “This type of test would help doctors tailor iron therapy, ensuring that high-risk patients get safer, more targeted treatment,” Dr. Booth says. 

In addition, genetic screenings can identify mutations in the genes that are associated with hemochromatosis, helping physicians determine who is or isn’t a good candidate for iron supplementation.

Though some physicians may choose to run this genetic test, it’s not routinely conducted before recommending iron supplementation. “This is one of those areas where the patient has to be their own advocate to get the testing they need,” Best says