Iron: What It Does, How Much You Need, and Where to Get It

Iron carries oxygen through your blood, but too little or too much can both cause problems.

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By the Ration Editorial Team · Reviewed against primary research · Updated July 14, 2026

Iron is an essential mineral. Your body needs it to build hemoglobin, the protein inside red blood cells that grabs oxygen in your lungs and drops it off everywhere else.

Iron also helps make myoglobin, a similar protein in muscle tissue.

It supports energy production inside cells and plays a role in making some hormones and connective tissue.

Unlike many nutrients, iron is tightly recycled by the body. Old red blood cells are broken down and their iron is reused, which is one reason needs are relatively modest compared to how much iron is actually circulating.

Iron comes in two dietary forms.

• Heme iron, found in meat, poultry, and fish, is absorbed efficiently by the gut.
• Non-heme iron, found in plants and fortified foods, is absorbed less efficiently and is sensitive to what else is on your plate.

Vitamin C can boost absorption of non-heme iron when eaten in the same meal. Compounds in tea, coffee, and whole grains, such as tannins and phytates, can reduce it.

Calcium may also blunt iron absorption if taken together in large amounts.

Once absorbed, iron is shuttled through the blood by a protein called transferrin and stored in the liver, spleen, and bone marrow as ferritin.

Iron deficiency is one of the most common nutrient shortfalls worldwide.

Early on, low iron can cause fatigue, weakness, and trouble concentrating, even before anemia shows up on bloodwork.

Left unaddressed, it can progress to iron deficiency anemia, marked by pale skin, shortness of breath, dizziness, brittle nails, and cravings for non-food items like ice, a condition called pica.

• Women with heavy menstrual periods
• Pregnant people, whose blood volume expands substantially
• Infants and toddlers, especially if weaned onto low-iron diets
• People who follow vegetarian or vegan diets
• Frequent blood donors
• People with conditions that affect gut absorption, such as celiac disease
• Endurance athletes, who can lose iron through sweat and foot-strike red blood cell breakdown

Yes. Iron overload is a real risk, particularly for people with hereditary hemochromatosis, a genetic condition that causes the body to absorb too much iron from food.

Excess iron can build up in the liver, heart, and pancreas over years and contribute to organ damage.

Acute iron overdose, most often from supplements accidentally swallowed by children, is a medical emergency and a leading cause of poisoning deaths in young kids.

Because of this risk, iron supplements are generally not recommended without a documented deficiency.

Needs vary a lot by age, sex, and life stage.

• Adult men and postmenopausal women generally need less, since they have no monthly blood loss.
• Adult women of reproductive age typically need roughly double the iron of men, due to menstrual losses.
• Pregnancy substantially increases iron needs to support increased blood volume and fetal growth.
• Infants, especially after 6 months, need reliable iron sources as they outgrow the stores they were born with.

Because plant-based iron is absorbed less efficiently, some guidelines suggest people eating vegetarian or vegan diets may need close to double the standard recommendation.

Iron shows up in both animal and plant foods, though amounts and absorbability differ.

• Red meat, liver, and other organ meats
• Poultry and fish, including sardines and oysters
• Beans, lentils, and chickpeas
• Tofu and other soy foods
• Spinach and other dark leafy greens
• Pumpkin seeds
• Fortified cereals and breads
• Quinoa

Pairing plant iron sources with vitamin C rich foods, like citrus fruit or bell peppers, may help the body absorb more of it.

Iron supplements are typically reserved for people with confirmed low iron or diagnosed anemia, usually identified through bloodwork.

Common forms include ferrous sulfate, ferrous gluconate, and ferrous fumarate, which differ mainly in how much elemental iron they deliver and how they sit with the stomach.

Iron supplements are well known for causing constipation, nausea, and dark stools. Taking them with food can ease stomach upset, though this may also slightly lower absorption.

Because unnecessary supplementation carries real risks, checking iron status before starting is generally the more cautious approach rather than taking iron speculatively for fatigue.

Iron is essential for carrying oxygen through the body, and both too little and too much can cause real harm.

Most people can meet their needs through a varied diet that includes meat, seafood, legumes, and iron-fortified foods, paired thoughtfully with vitamin C sources.

People at higher risk of deficiency, such as menstruating women, pregnant people, and those on plant-based diets, may want to pay closer attention to their intake and discuss testing with a healthcare provider before considering supplements.