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 crucial roles of iron include:
To carry oxygen around the body – 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.
Ensuring a healthy immune system – 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.
Making energy – iron is essential for the body's chemical reactions that produce energy from food. 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.
In New Zealand
Research shows thousands of New Zealanders, particularly those in the at-risk groups, are iron deficient.
Could you be iron deficient?
The symptoms of iron deficiency are commonly associated with a ‘busy lifestyle’ or ‘a bug’. If you can tick any of the boxes you may be short of iron.
Feel tired or lethargic
Often irritable or grumpy
Suffer frequent infections
Feel the cold
Tire easily
Can’t concentrate
If you are concerned that you may be low in iron it is important to go to your doctor and get a blood test. Only take iron supplements if advised by a doctor.
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.
120g of beef or 19 cups of cooked silverbeet provides a quarter of a woman’s daily iron needs
Not all iron is created equal
Not all iron is created equal, for example, eating just 120g of lean rump beef steak provides the same amount of absorbable iron as 19 cups (1400g) of cooked silverbeet.
120g of beef or around 19 cups of cooked silverbeet provides a quarter of a woman’s daily absorbable iron needs.
YOUR BODY CAN USE ABOUT 15-25% OF THE IRON IN RED MEAT, BUT ONLY ABOUT 5-12% OF THE IRON IN SILVERBEET.
Iron: Where is it?
Iron is found in a number of foods, including red meat. In general the redder the meat, the higher the iron content. But not all iron is the same. Iron is found in two forms: haem and non-haem.
Haem iron foods:
Beef
Lamb
Liver
Kidney
Pork
Poultry
Seafood
in general the redder the meat the higher the iron content.
Non-haem iron foods:
Bread
Breakfast cereal
Beans and lentils
Eggs
Nuts
Seeds
Fruit and vegetables.
In addition haem iron foods contain non-haem iron.
The body absorbs haem iron more easily, with about 15-25% being used. Only about 5-12% of non-haem iron is absorbed.
How can I absorb more iron?
Red meat can help to increase iron absorption. When you eat beef or lamb, together with veges, the amount of non-heme iron absorption from veges 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.
Can I get enough iron on a vegetarian diet?
Well-absorbed haem iron is only found in animal foods - red meat, poultry and fish. The removal of these haem iron foods from the diet greatly reduces absorption of iron.
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, the poorly absorbed form of iron, is generally the only source of iron in their diet. Vegetarians can meet their daily iron requirements, but it takes very careful planning.
How can I find out if I'm iron deficient?
The only way to find out for sure if you are iron deficient is to go to your doctor and get a blood test. 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.
Possible Clinical Effects of Iron Deficiency
Fatigue and reduced tolerance to work
Developmental delay and learning difficulties
Reduced resistance to the cold
Impaired immunity (increased frequency of infections)
Reduced appetite
Deterioration in athletic performance due to decreased aerobic capacity
Premature births and low birth weights
Long-term iron deficiency leads to anaemia with more severe symptoms.
For more information about iron:
Thousands of New Zealanders don’t get enough iron
Fuelled by Iron – Babies and Toddlers
Podcast: The Silent Epidemic: Iron deficiency is suffocating our teen girls
Ten tips to improve your iron intake
Iron in infants and young children
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