Iron and Blood Health: What You Need to Know

           By Maria Shafiq | Founder & Health Research Writer, The Veins Vercel | Updated: October 16, 2026

Medical disclaimer: This article is for educational purposes only and is not medical advice, diagnosis or treatment. Talk to a qualified healthcare provider before starting iron supplements or if you think you may be deficient.

Iron carries oxygen in your blood, and your heart has to work harder when there is not enough of it. Iron deficiency is one of the most common nutrient deficiencies in the world. The WHO estimates that roughly 3 in 10 women of reproductive age worldwide have anaemia, and iron deficiency is a leading cause [2]. Too much iron can also be harmful. This guide explains what iron does, how deficiency can affect the heart and circulation, how to get enough from food, and when to see a doctor instead of self-treating.

What Iron Does in the Body

Iron is an essential mineral. About 60 to 70 percent of the body’s iron is in hemoglobin, the protein in red blood cells that carries oxygen from the lungs to tissues. Iron is also part of myoglobin in muscle and of enzymes involved in energy production in cells [1].

The body cannot make iron and has no active way to excrete extra. It controls iron mainly by adjusting how much it absorbs, using a hormone called hepcidin. Excess iron is stored as ferritin, mostly in the liver, and small amounts are lost daily through shed skin and gut cells, and in blood loss such as menstruation.

There are two forms of dietary iron:

• Heme iron is found in meat, poultry and fish. It is absorbed relatively well, roughly 15 to 35 percent.
• Non-heme iron is found in plant foods, eggs, dairy and fortified foods. It is absorbed less efficiently, roughly 2 to 20 percent, and absorption depends heavily on what else is eaten with it [1][6].

How Iron Deficiency Can Affect the Heart and Circulation

When iron is low, the body makes fewer or smaller red blood cells, which can lead to iron deficiency anaemia. With less oxygen-carrying capacity, the heart compensates by beating faster and pumping more blood. In people with healthy hearts this may cause only palpitations and breathlessness on exertion. In people with existing heart disease, anaemia can worsen angina and heart failure symptoms [4][5].

Iron deficiency is especially common in people with heart failure, even without anaemia, and it is linked to worse exercise capacity and quality of life. The 2022 American Heart Association, American College of Cardiology and Heart Failure Society of America guideline says that intravenous iron replacement is reasonable for people with heart failure with reduced ejection fraction and iron deficiency, to improve function and quality of life [3]. This is a treatment decision for doctors. It is not something to try with over-the-counter tablets.

Iron deficiency affects more than the heart. Iron-dependent enzymes are needed for energy production in all cells, including cells that line blood vessels. Low iron can contribute to fatigue, reduced exercise tolerance and poor concentration.

Signs You May Be Low in Iron

Symptoms develop slowly and are not specific. Many have other causes, so a blood test is needed to confirm.

• Persistent tiredness or weakness
• Shortness of breath or a racing heartbeat on mild exertion
• Pale skin or pale inner eyelids
• Dizziness or headaches
• Cold hands and feet
• Brittle nails, or spoon-shaped nails in advanced deficiency
• Hair shedding
• Restless legs, which are linked to low iron stores
• Cravings to chew ice or eat non-food items (called pica)

Groups at higher risk include menstruating women, especially with heavy periods, pregnant women, infants and toddlers, frequent blood donors, endurance athletes, people who eat vegetarian or vegan diets without planning, and people with celiac disease, inflammatory bowel disease, bariatric surgery or long-term use of acid-reducing medicine [1][8].

Important: In men and in women after menopause, iron deficiency is unusual and often a sign of slow blood loss, for example from the digestive tract. It needs a medical evaluation to find the cause and should not be treated with supplements alone.

How Much Iron Do You Need?

Recommended daily amounts from the U.S. National Institutes of Health [1]:

The tolerable upper intake level for adults is 45 mg per day from all sources, mainly relevant to supplements [1].

Good Food Sources of Iron

Approximate iron content per serving, based on NIH Office of Dietary Supplements data [1]:

Salmon and canned tuna contain only small amounts of iron. They are good for other nutrients but are not strong iron sources. Liver is rich in iron but also very high in vitamin A, so pregnant women should limit it.

6 Practical Ways to Improve Iron Intake and Absorption

1. Include a vitamin C source with plant-based meals. Vitamin C helps convert iron into a form that is easier to absorb. Examples are lemon juice on lentil salad, bell peppers in bean chili, or fruit with fortified cereal [6].

2. Keep tea, coffee and calcium away from iron-rich meals. Polyphenols in tea and coffee, and large amounts of calcium, reduce absorption of non-heme iron. Drinking tea or coffee an hour or so before or after meals helps.

3. Soak, sprout or ferment grains and legumes. These methods reduce phytates, which bind iron and limit absorption [6].

4. Add a little meat, fish or poultry to plant meals. Animal protein improves absorption of non-heme iron eaten at the same meal.

5. Cook in cast iron. Acidic, moist foods such as tomato sauce cooked in a cast-iron pan can pick up a small amount of iron.

6. Treat the cause as well as the symptoms. Heavy periods, frequent blood donation, digestive disease and certain medicines can all lower iron. A doctor can help identify and treat these.

Testing and Supplements

Iron status is assessed with blood tests, which your doctor chooses and interprets:

• Complete blood count (CBC): Shows hemoglobin and red blood cell size. Iron deficiency anaemia usually gives low hemoglobin and small red cells.
• Serum ferritin: The most useful single test for iron stores. The WHO considers a ferritin below 15 micrograms per litre in healthy adults as evidence of depleted stores [2]. Ferritin rises with inflammation or infection, so a normal value does not always rule out deficiency.
• Transferrin saturation and serum iron: Help interpret ferritin, especially when inflammation is present.

If you are deficient, your doctor may recommend oral iron, usually taken once daily or on alternate days, and repeat testing to confirm it is working. Intravenous iron is used when oral iron is not tolerated or absorbed, or in conditions such as heart failure or chronic kidney disease [3][8]. Common oral iron side effects include constipation, nausea and dark stools.

Safety points about supplements:

• Do not take iron tablets unless a test or your doctor indicates you need them. Extra iron does not boost energy in people who are not deficient.
• Keep all iron products out of the reach of children. Accidental iron overdose is a leading cause of poisoning deaths in young children.
• Iron overload is dangerous. People with hemochromatosis, a genetic condition that causes excess iron absorption, can develop liver, heart and joint damage and should not take iron or vitamin C supplements unless advised by their doctor.
• Iron supplements can interact with some medicines, including thyroid hormone and some antibiotics. Ask a pharmacist about timing.

Can Too Much Iron Harm the Heart?

Yes, in specific conditions. In hemochromatosis and in repeated blood transfusions, excess iron can accumulate in the heart muscle and cause cardiomyopathy and rhythm problems. In the general population, the evidence linking higher iron stores to heart disease is mixed. Some studies suggest an association, while others do not, so no firm conclusion can be drawn. Because iron is regulated tightly and extra iron is hard to excrete, the practical advice is the same: avoid unnecessary iron supplements, and use testing to guide treatment.

Other Habits That Support Healthy Blood and Circulation

• Be active: Aim for at least 150 minutes per week of moderate exercise. Endurance athletes may lose more iron through sweat and gut bleeding, and hepcidin rises after hard exercise, which reduces absorption for a few hours, so they should have iron levels checked if they feel unusually tired.
• Eat a balanced diet with plenty of vegetables, legumes, whole grains and some animal or fortified foods.
• Sleep seven or more hours and manage stress, both of which are linked to better cardiovascular health.
• Check blood pressure regularly with a validated upper-arm monitor, and ask your doctor about routine blood tests that suit your age and risk factors.

When to See a Doctor

Call your local emergency number immediately if you have:

• Sudden chest pain, pressure or tightness, especially if it spreads to the arm, neck, jaw or back. Women may also have nausea, unusual fatigue, back or jaw pain, or shortness of breath without obvious chest pain.
• Sudden severe shortness of breath, fainting or a very fast or irregular heartbeat with lightheadedness.
• Vomiting blood, black tarry stools or heavy rectal bleeding.
• Sudden confusion, difficulty speaking, or weakness on one side of the body.

Book a doctor’s appointment if you have ongoing fatigue, breathlessness on mild exertion, heavy periods, or other signs of low iron, if you are pregnant or planning pregnancy, or if you are a man or postmenopausal woman with suspected iron deficiency [7].

Frequently Asked Questions

Will iron-rich foods boost my energy right away? No. If you are deficient, it usually takes weeks of treatment for hemoglobin to rise and several months to rebuild iron stores. If you are not deficient, extra iron will not increase energy.

Can I get enough iron on a vegetarian or vegan diet? Yes, with planning. Vegetarians need about 1.8 times the standard recommended amount. Legumes, tofu, seeds, whole grains and fortified foods, eaten with vitamin C sources, can meet needs. Ask your doctor to check your ferritin periodically.

What is the difference between serum iron and ferritin? Serum iron measures iron currently circulating in the blood and varies during the day and with recent meals. Ferritin reflects stored iron and is more useful for diagnosing deficiency, but it can be raised by inflammation, so doctors usually interpret it with other tests.

Why do tea and coffee reduce iron absorption? Polyphenols and tannins in tea and coffee bind non-heme iron in the gut and make it harder to absorb. Having them between meals instead of with meals reduces this effect.

Can I take iron every day to be safe? Not unless you are deficient or advised to. Regular unnecessary iron supplements can cause stomach side effects and, in people who absorb iron excessively, can lead to overload.

Conclusion

Iron supports oxygen delivery and energy production, and deficiency can cause fatigue, breathlessness and extra strain on the heart, particularly in people with existing heart disease. Most people can meet their needs through a varied diet that includes iron-rich foods and vitamin C. Supplements should be taken when a test and a doctor show a need, and the cause of deficiency should always be identified. If you suspect low iron, get tested instead of guessing.

Editorial note: This article was researched from peer-reviewed literature, clinical guidelines and public health sources. [Add a disclosure here if any linked guides or products on this site are commercial or affiliate.]

References

1. 1. National Institutes of Health, Office of Dietary Supplements. Iron: Fact Sheet for Health Professionals. https://ods.od.nih.gov/factsheets/Iron-HealthProfessional/
   2. World Health Organization. Anaemia (fact sheet). https://www.who.int/news-room/fact-sheets/detail/anaemia. See also: WHO guideline on use of ferritin concentrations to assess iron status in individuals and populations (2020).
   3. Heidenreich PA, et al. 2022 AHA/ACC/HFSA Guideline for the Management of Heart Failure. Circulation. 2022;145:e895-e1032.
   4. Métivier F, et al. Pathophysiology of anaemia: focus on the heart and blood vessels. Nephrol Dial Transplant. 2000;15(Suppl 3):14-18.
   5. Camaschella C. Iron-deficiency anemia. N Engl J Med. 2015;372:1832-1843.
   6. Hurrell R, Egli I. Iron bioavailability and dietary reference values. Am J Clin Nutr. 2010;91(5):1461S-1467S.
   7. Mayo Clinic. Iron deficiency anemia: Symptoms and causes. https://www.mayoclinic.org/diseases-conditions/iron-deficiency-anemia/symptoms-causes/syc-20355034
   8. Pasricha SR, et al. Iron deficiency. Lancet. 2021;397:233-248.