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Iron In The Human Body: Benefits And Side Effects

Iron is vital in the production of red blood cells, important in transporting oxygen to different parts of the body. It also converts the glucose in your blood to energy, thus maintaining metabolism. Iron also plays a key role in immunity, nerve, and brain function. Include meat, seafood, spinach, and beans in your diet to maintain optimum iron levels. However, make sure you don't intake more than the required amount of 18 mg/day.

If you’re anemic, pregnant, suffering from kidney disease, or are undergoing chemotherapy, you’ve probably been advised to increase your iron intake. Though iron is a nutrient essential for the functioning of your body, over 30 percent of the global population suffers from iron deficiency. So, what exactly does iron do and why do you need it?

1. Helps Produce Red Blood Cells

The most well-documented function of iron in the body is in the production of red blood cells (RBC). In fact, blood owes its red hue to iron. Once iron enters your body, it’s transported to the bone marrows where it helps produce new red blood cells and hemoglobin. Since the lifespan of RBCs in your bloodstream is only about 120 days, your body needs a constant supply of iron to replenish the hemoglobin and RBC levels.1

If your RBC count is low due to the lack of iron, you could experience weakness, fatigue, shortness of breath, an increased heart rate, headaches, and dizziness. For a healthy RBC count, it’s essential that you eat iron-rich food and prevent iron-deficiency anemia.

2. Transports Oxygen

Hemoglobin, the iron-containing protein in red blood cells, is in charge of transporting oxygen from the lungs to different parts of the body. Lack of iron reduces the level of hemoglobin, which in turn deprives vital organs and body parts of oxygen, eventually causing cell death.2

3. Helps In Muscle Function

Iron is also essential for the production of a certain protein called myoglobin. Myoglobin binds to the oxygen in your muscle cells and stores it for future use. It also helps in the metabolic processes required for muscle contraction by transporting oxygen within the muscle tissue.3 So a lack of iron will manifest as muscle weakness and pain caused by a low supply of oxygen and nutrients.

4. Helps In Metabolism

You may think that iron has no role to play in controlling your metabolism. But lack of iron makes cells resistant to insulin and prevents the conversion of glucose into energy. This signals the body that there might be a lack of insulin. So the body increases insulin production. Now both high insulin and lack of blood sugar conversion contribute to obesity, type 2 diabetes, and heart disease risk. In fact, in patients of heart failure, iron deficiency is considered a fatal risk factor.4

5. Helps In Immunity

To keep diseases at bay and fight cell-damaging free radicals, your immune system needs the help of certain antioxidants like catalase and peroxidase. These antioxidants depend heavily on iron supply to work effectively. If you don’t have enough in iron in your body, your immunity might be compromised and you could become prone to infections.

Iron also has a role to play in the production of cytokines, which are substances released by your immune cells to aid cell-to-cell communication during an immune response.5 If your cytokine levels are low, you could experience chronic inflammation, pain, and poor immunity.

6. Helps Prevent Brain Diseases

Your brain requires slightly more oxygen than other parts of the body to work optimally. Lack of iron can reduce oxygen supply to the brain. Low levels of iron and hemoglobin will also induce oxidative stress of brain cells, which will gradually lead to cell death.6

An untreated iron deficiency can put you at a high risk of memory disorders like Alzheimer’s and dementia. Lack of iron can also alter your dopamine (your body’s feel-good hormone) levels, thereby affecting your mood.7

7. Helps Maintain Brain Function

Iron also has a more direct role in brain health. Some very important nerves in our body are partially covered by a protective sheath called myelin sheath, which makes the transmission of nerve impulses or signals super fast (think of nerves that need to conduct information about balance). Iron has a role to play in the synthesis of myelin in the early stages of life, in maintaining the integrity of the myelin sheath, and also in repairing damaged myelin sheaths.8

This is why lack of iron when one is young often leads to slow development of brain faculties, language, IQ, and motor skills and is also linked with a tendency toward anxiety, depression, and ADHD.9 In fact,  low levels of iron in newborns can impair their learning ability, and even long-term iron supplementation in the future might not reverse the condition.10

Adult Men Need 8 Mg Iron A Day, Women Need 18 Mg

Having noted how vital iron is for our survival, let’s find out how much iron we need daily. The amount of iron required varies with age and gender. Menstruating women obviously need more since they lose more iron every month. Infants also need more iron for development of the brain and for other body functions.11

Here is the recommended daily allowance for iron.


Age Male Female
Birth to 6 months 0.27 mg 0.27 mg
7–12 months 11 mg 11 mg
1–3 years 7 mg 7 mg
4–8 years 10 mg 10 mg
9–13 years 8 mg 8 mg
14–18 years 11 mg 15 mg
19–50 years 8 mg 18 mg
51+ years 8 mg 8 mg

Pregnant Women Have A Higher Risk Of Deficiency

A pregnant woman needs 27 mg, while a lactating woman needs 11 mg iron per day.

Pregnant women, children, and the elderly are more prone to iron deficiency than others. This is because, during pregnancy, iron is used extensively in forming vital aspects of the fetus. For growing children, the demand for iron may increase over time but the iron in the diet, in most cases, does not increase. Elderly men/women naturally lose iron through metabolism and may require supplements to prevent deficiency. This loss is natural. Iron depletes with age and the reduced absorption power of the digestive tract.

Vegetarians And Vegans Need More Iron

Did you know tea antioxidants block the absorption of non-heme iron in your body? So drink tea between your meals and add some lemon juice to your tea as vitamin C helps in the absorption of iron.12

Iron in our diet comes from two sources: animal sources or heme iron, and plant sources or nonheme iron. Since heme iron is better absorbed by the body, a vegetarian or vegan would need almost twice the daily recommended amount of iron.13

Include iron-rich foods like spinach, beans, dry fruits, broccoli, wheat germ, prunes, and peaches to your daily diet. Consume a fair amount of meat and seafood as well. Here’s a list of the top 10 iron-rich foods.

Food Quantity Of Iron (in mg) Standard Serving Size
Liver, pork, cooked 13.4 75 g (2 ½ oz)
Liver (chicken, turkey, lamb), cooked 6.2–9.7 75 g (2 ½ oz)
Kidney, lamb, cooked 9.3 75 g (2 ½ oz)
Octopus, cooked 7.2 75 g (2 ½ oz)
Soybeans, mature, cooked 6.5 175 mL (¾ cup)
Cream of wheat, all types, cooked 5.7-5.8 175 mL (¾ cup)
Liver, beef ,cooked 4.9 75 g (2 ½ oz)
Lentils, cooked 4.1-4.9 175 mL (¾ cup)
Oatmeal, instant, cooked 4.5-6.6 175 mL (¾ cup)
Cereal, dry, all types 4.0-4.3 30 g


Iron Deficiency Has Several Causes And Wide-Ranging Symptoms

Lack of iron-rich foods as part of your daily diet and low iron absorption are the most common reasons for a deficiency. Iron deficiency can also happen due to loss of excess blood (such as during heavy menstruation), excessive blood donation, fibroids, and digestive tract infection or disease. Certain medications can also restrict iron absorption or cause depletion.

Deficiency of iron can cause chronic fatigue, weakness, dizziness, inability to concentrate, headaches, depression, sore tongue, increased sensitivity to cold, shortness of breath, and restless leg syndrome.

Excess Iron Too May Cause Iron Toxicity

While iron is healthy for the body, excess iron can do more harm than good and lead to a condition called iron toxicity. Iron ions cause oxidative stress through the formation of oxygen free radicals. These free radicals can oxidize lipids in cell membranes, leading to cell death. This type of iron-induced oxidation has been linked to age-related memory diseases like Alzheimer’s and Parkinson’s.

Iron toxicity is rare because the body uses it in one way or another. However, regulate your iron intake if you suffer from hemochromatosis – a genetically inherited disease that can cause iron to accumulate to toxic levels in the body. Without treatment, this disease can lead to problems like liver cancer, liver cirrhosis, and heart disease.

If you have an iron deficiency, you might want to consider taking supplements. However, consult your doctor before opting for any kind of supplement as excess iron, as discussed, can be harmful.

References   [ + ]

1. The Interaction of Iron and Erythropoietin. Harvard University.
2. The Chemistry of Hemoglobin and Myoglobin. Purdue University.
3. The Chemistry of Hemoglobin and Myoglobin. Purdue University.
4. Makubi, Abel, and David J. Roberts. “Investigation and treatment for iron deficiency in heart failure: the unmet need in Lower and Middle Income Countries.” British journal of haematology (2017).
5. Jason, J., et al. “The effects of iron deficiency on lymphocyte cytokine production and activation: preservation of hepatic iron but not at all cost.”Clinical & Experimental Immunology 126.3 (2001): 466-473.
6. Meneghini, Rogerio. “Iron homeostasis, oxidative stress, and DNA damage.”Free Radical Biology and Medicine 23.5 (1997): 783-792.
7. Lozoff, Betsy. “Early Iron Deficiency Has Brain and Behavior Effects Consistent with Dopaminergic Dysfunction–3.” The Journal of nutrition 141, no. 4 (2011): 740S-746S.
8. Todorich, Bozho, et al. “Oligodendrocytes and myelination: the role of iron.”Glia 57.5 (2009): 467-478.
9. Hare, Dominic J., Scott Ayton, Ashley I. Bush, and Peng Lei. “A delicate balance: iron metabolism and diseases of the brain.” Frontiers in aging neuroscience 5 (2013): 34.
10. [ref]Youdim, Moussa BH. “Brain iron deficiency and excess; cognitive impairment and neurodegenration with involvement of striatum and hippocampus.” Neurotoxicity research 14, no. 1 (2008): 45-56.
11. Iron. National Institutes of Health.
12. Zijp, Itske M., Onno Korver, and Lilian BM Tijburg. “Effect of tea and other dietary factors on iron absorption.” Critical reviews in food science and nutrition 40, no. 5 (2000): 371-398.
13. Food Sources of Iron. Dieticians of Canada.

Disclaimer: The content is purely informative and educational in nature and should not be construed as medical advice. Please use the content only in consultation with an appropriate certified medical or healthcare professional.