Iron is a mineral found in some foods and is essential for good health and for physical and mental well-being. Iron deficiency is the most common nutritional disorder in the world.
Why do we need iron?
Iron has many functions in the body but the main three roles of iron include:
Oxygen transport – every cell in the body needs oxygen and iron carries oxygen around the body in our blood. There is iron in the haemoglobin of red blood cells and it carries oxygen from your lungs to the rest of the body.
Immune system support – the cells that fight infection depend on adequate stores of iron. This means if your iron stores are low, your body is more prone to infections.
Energy production – iron is essential for the body's chemical reactions that help unpack energy from the food we eat. This means if your iron levels are low, your body may not be able to use all the energy available.
Who needs iron the most?
There are certain groups of people who have higher iron needs. These include:
Infants, children and teenagers because they are growing rapidly
Pregnant women for increased blood levels and to build baby’s iron stores.
Girls and women who have periods, due to regular monthly blood loss.
Athletes and very active people
People on restrictive or alternative diets
In New Zealand
40% of infants and 1 in 5 toddlers are consuming inadequate amounts of iron
14% of children under the age of 2 are iron deficient
Over 1/3 of teenage girls don’t achieve their daily iron requirements
1 in 14 women are low in iron
Research shows thousands of New Zealanders, particularly those who have higher iron needs, are iron deficient.
Could you be iron deficient?
The symptoms of iron deficiency are commonly associated with a ‘busy lifestyle’ or ‘a bug’, they can include:
You feel tired or lethargic
You’re often irritable or grumpy
You may get frequent infections
You often feel the cold
You find it hard to concentrate
If you have one or several of these symptoms you may be low in iron. Make an appointment with your GP to get your iron stores checked.
You should be aware there are several different tests for iron status. The first of these is haemoglobin, which effectively measures circulating amounts of iron. Haemoglobin does not reflect your long-term iron stores. For that, you need a serum ferritin test. It is possible to have normal haemoglobin levels, but low storage (ferritin) iron. Transport (transferrin) iron is another important indicator, which measures the amount of iron supplied to the bone marrow.
How much iron do we need each day?
The body is incredibly efficient, more dietary iron can be absorbed when the body’s iron stores are low. Likewise, less iron can be absorbed when iron stores are full. But to maintain healthy iron levels the following iron intake (mg) is recommended daily for different life stages.
The recommended dietary intake (RDI) for iron is based on an estimated 15-25% of dietary iron is absorbed. For example, a women aged 19-50 years with a RDI of 18mg needs to eat that much for it to provide at least 2.7mg of absorbable haem iron.
What foods is iron found in?
Iron is found in lots of foods, including beef and lamb.
Not all iron is the same, iron is found in two forms: haem and non-haem. Our bodies absorb the haem iron found in animal-sourced foods more easily than the non-haem iron found in plant foods.
Your body can use about 15-25% of the iron in haem iron foods, but, only about 5-12% of the iron in non-haem containing foods. In general the redder the meat, the higher the iron content.
Haem iron foods: beef, lamb, liver, pork, venison, poultry and mussels
Non-haem iron foods: bread, breakfast cereals, beans and lentils, nuts, vegetables
Not all iron is created equal, for example, eating just 120g of lean beef rump steak provides the same amount of absorbable iron as 19 cups (1400g) of cooked silverbeet. This is about a quarter of a woman’s daily absorbable iron needs.
How can I absorb more iron?
Red meat can help to increase iron absorption. When you eat beef or lamb, together with vegetables, the amount of non-haem iron absorbed from the vegetables will increase. Vitamin C has a similar effect. Eating a combination of foods high in both haem and non-haem iron will ensure an iron-rich diet, for example a beef and vegetable stir-fry is a great iron-rich meal.
If I’m vegetarian, can I get enough iron?
Well-absorbed haem iron is only found in animal-sourced foods. The removal of these haem iron foods from the diet greatly reduces iron absorption.
Vegetarians need to consume proportionally more iron to meet their daily iron needs as they are relying on non-haem iron.
For most vegetarians, non-haem iron (not as well absorbed), is generally the only source of iron in their diet. Vegetarians can meet their daily iron requirements, but it takes careful planning.
References
Grant, CC et al. (2007). Population prevalence and risk factors for iron deficiency in Auckland, New Zealand. J Paediatr Child Health 43: 532-538.
Ministry of Health. 2003. NZ Food NZ Children: Key results of the 2002 National Children’s Nutrition Survey. Wellington: Ministry of Health.
National Health and Medical Research Council (NHMRC), Nutrient Reference Values for Australia and New Zealand including recommended dietary intakes: April, 2014.
New Zealand Food Composition Database 2019. New Zealand Food Composition Database Online Search. The New Zealand Institute for Plant & Food Research Limited and Ministry of Health.
Wall, CR et al. (2008). Ethnic variance in iron status: is it related to dietary intake? Public Health Nutr 12 (9):1413-1421