You breathe more than 20,000 times a day, delivering life-giving oxygen to every cell in your body, but oxygen doesn’t reach the cells by itself. It hitches a ride on hemoglobin, a protein found in red blood cells. And there’s a “seatbelt” in hemoglobin that keeps oxygen in place: the mineral iron. In fact, 70 percent of the iron in the body is used for this crucial function. Bottom line: Without iron, your cells would suffocate, and so would you. No wonder scientists call this mineral essential.

Iron plays a role in many other functions that are fundamental to life, including synthesizing DNA, which controls the reproduction, growth, and repair of cells; generating adenosine triphosphate (ATP), the fuel that powers cells; and helping to activate enzymes that regulate hormones and detoxify the body.

Iron overload

Iron is so important to the health of the cells, tissues, and organs of the body that there is no physiological mechanism for iron excretion from the body. And that may create or contribute to a health problem few people know about—a health problem that may threaten the well-being and longevity of more than 10 million Americans: dysmetabolic iron overload syndrome (DIOS).

Dysmetabolic, because DIOS afflicts an estimated 15 percent of people with metabolic syndrome. Metabolic syndrome is a cluster of disorders that increases your risk for type 2 diabetes, heart attack, stroke, nonalcoholic fatty liver disease (itself a risk factor for cirrhosis and liver cancer), and chronic kidney disease. Those disorders include abdominal obesity (a waist circumference of more than 35 inches for women and more than 40 inches for men); high blood pressure (a reading of 130/80 or higher); prediabetes (a fasting glucose level of 100 mg/dL or higher); high levels of the blood fat triglycerides (more than 150 mg/dL); and low levels of “good” HDL cholesterol (less than 40 mg/dL for men and less than 50 mg/dL for women).

If you have three or more of these factors, you have metabolic syndrome, according to the American Heart Association. But you’re hardly alone. One in three Americans (including 42 percent of people ages 60 and older) have metabolic syndrome, according to the National Institutes of Health. That’s 86 million Americans with metabolic syndrome and an estimated 13 million with DIOS.

Excess iron and your liver

Medical experts are still working out the complex links between metabolic syndrome and excess iron, but they know the problem is probably what scientists call bidirectional: Excess iron worsens metabolic syndrome, and metabolic syndrome imbalances the normal way iron is used by the body. Whatever the links between metabolic syndrome and iron overload, there’s one fact that medical experts agree on: Higher-than-normal levels of stored iron can damage the body in many ways.

Iron is very good at helping electrons move around, a crucial step in the chemical reactions that generate ATP. But the volatility of its electrons also means that excess iron—the kind that is not bound to a protein for a biological purpose—generates free radicals, unstable molecules that are missing an electron and that attack other molecules for their electrons, causing damage.

Excess iron can cause damage to organs throughout the body:

  • the liver, leading to scarring (cirrhosis), liver failure, and possibly liver cancer
  • joints, causing pain and stiffness
  • the pancreas, impairing the secretion of insulin, the hormone that regulates blood sugar
  • other hormone-generating glands, reducing the function of the thyroid, adrenals, testes, or ovaries
  • the heart, causing cardiomyopathy (disease of the heart muscle), arrhythmia (irregular heartbeats), and heart failure
  • the immune system, causing increased vulnerability to viral and bacterial infections.

These problems are commonly seen in hemochromatosis, a genetic disease that causes iron overload. In DIOS, the damage caused by excess iron is primarily seen in the liver, where much of the body’s iron is stored.

This higher-than-normal level of iron can complicate metabolic dysfunction-associated steatotic liver disease (MASLD), a buildup of fat in the liver that triggers inflammation and scarring (see page 22.) Three out of four people with metabolic syndrome have MASLD. Excess iron can also hasten the progression of MASLD to metabolic dysfunction-associated steatohepatitis (MASH) and on to cirrhosis, liver failure, liver cancer, and death.

“DIOS is becoming a relevant finding in the general population and can be associated with high morbidity [disease] and mortality [death],” concluded a team of Brazilian scientists, in a scientific paper on DIOS, published in 2023 in the journal Endocrines.


If you’ve been diagnosed with metabolic syndrome, it’s prudent to find out if you have excess levels of iron. The simplest way to detect excess iron is a blood test for levels of ferritin, a protein that stores iron in your cells. In adults, the normal ranges for ferritin are 24 to 336 nanograms per milliliter (ng/mL) in men, and 24 to 307 in women. A study in the journal Hepatology, from researchers at the Center for Liver Disease at the Virginia Mason Medical Center in Seattle, found that ferritin levels above 300 in women and 400 in men were directly linked with more severe MASLD and progression to MASH, and a 66 percent greater risk of liver scarring. Other ways to measure excess iron include a blood test for transferrin saturation, detecting iron in a liver biopsy, and detecting elevated iron with magnetic resonance imaging (MRI).

Lowering iron levels

People with hemochromatosis control their high iron levels by regularly donating blood, and medical experts thought the same approach might work for DIOS. But several clinical studies show that it doesn’t have any affect on the problem.

There is a simple and straightforward way to lower the high iron levels linked to metabolic syndrome: Eat less red meat (beef, pork, lamb). In a study published in the journal Nutrients in 2023, Dr. Pantopoulos and a colleague took a comprehensive look at the scientific literature linking iron and the risk for metabolic syndrome, and for diseases caused by metabolic syndrome like type 2 diabetes and cardiovascular disease. They reported multiple findings:

  • Metabolic syndrome was linked to the intake of heme iron, the type of iron found in animal products like red meat. People with the highest intake of heme iron had a 25 percent higher risk of developing metabolic syndrome.
  • High levels of ferritin were linked to type 2 diabetes, increasing risk by up to 70 percent.
  • A high intake of heme iron was linked to a 57 percent increase in the risk of heart disease and a 19 percent increase in the risk of dying from cardiovascular disease.
  • In these and other studies, the main source of heme iron in the diet was red meat.

On the other hand, there is no evidence that the dietary intake of so-called “inorganic iron” (a chemical term, not an agricultural one) from plant foods, fortified food, or iron supplements is linked to disease.

If you have metabolic syndrome, limit your intake of red meat. The World Cancer Research Fund, for example, recommends three servings of meat per week, or a total of 12 to 18 ounces. For health and longevity, people with metabolic syndrome should also exercise regularly (for example, a brisk walk of 30 minutes at least five days a week), lose weight (using a proven program, like Weight Watchers or Noom), and consider taking medication to address high blood fats, high blood sugar, and excessive body weight.

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