Introduction
Iron is the most abundant essential trace mineral in the human body.
It’s is an essential component of haemoglobin, a protein that transfers oxygens from the lungs to the tissues and all parts of the body. [1] Without enough iron, there aren’t enough blood cells to transport oxygen, which leads to extreme fatigue.
It is readily available in foods as well as in health supplements and comes in two forms – heme and non-heme. Meat, seafood and poultry are rich in both heme and non-heme whereas non-heme, iron is found abundantly in the plant-based diets as well as in iron-fortified foods.
World Health Organization(WHO) estimates that half of the 1.62 billion anaemia cases worldwide are due to iron deficiency[1].
In 2002, Iron deficiency anaemia (IDA) was characterised as one of the 10 leading risk factors for disease around the world by the WHO. [1]
- Iron absorption occurs in the upper small intestine. [2]
- Heme iron is better absorbed by the body (around 25% absorption rate) than non-heme iron (16% absorption rate) and adult men need to absorb around 1 mg/day whereas menstruating women need to absorb around 1.5 mg/day. [1,2]
- However, the quantity of non-heme iron is manyfold greater than that of heme-iron in most meals. Thus, despite its lower bioavailability, non-heme iron generally contributes more to iron nutrition than heme iron. [9]
- Also, major inhibitors of iron absorption are phytic acid, polyphenols and calcium. [2,9]
- Total iron content in the body is estimated at around 3-5g. [1,6]
- Most of the iron is stored in haemoglobin and the remaining is stored in the liver, spleen, bone marrow, and muscle tissues as ferritin. [1,2,4]
- This ferritin could stay in a man’s body for about 3 years while it remains in a woman’s body only for about 6 months. [10]
- Transferring is the main protein that binds to iron and transports it throughout the body. [1]
- Apart from iron losses due to menstruation, bleeding or pregnancy, iron is highly conserved and not readily lost from the body. [7,8,9]
- It’s not actively excreted through urine or through intestines but only through the skin, urinary tract or airways[7,9].
- The average iron loss for adults is estimated to be around 0.8-1 mg/day whereas for menstruating women it is in the range of 1.36 mg/day. [7,8,9]
Body Functions
Recommended Daily Intake
Deficiency Symptoms
Iron Food Sources
Excessive Intake/ Toxicity Side Effects
Groups At Risk of Iron Deficiency
Iron Interaction With Other Nutrients
- Vitamin A deficiency coexists with iron deficiency and may exacerbate iron-deficiency anaemia by altering iron metabolism. [4,8]
- Calcium – The presence of calcium may decrease absorption from both heme and non-heme food sources. [1,4]
- Zinc – Excessive iron intake can reduce zinc absorption. On the other hand, iron deficiency can coexist with zinc deficiency and can exacerbate anaemia. [4]
- Vitamin C – Consuming vitamin C foods with heme iron can improve the absorption rate of non-heme iron plant sources. [1,3] Each non-haem iron-rich meal should be consumed with at least 25 mg or more of ascorbic acid to improve iron absorption. [7]
- Copper – Adequate copper reserves are essential for red blood cells formation and efficient iron metabolism. [4]
Nutrient Profiles For Food Groups
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