Ask a Dietitian: Why Is Iron So Important?

Iron is an essential micronutrient in our body, and yet also one of the most common nutritional deficiencies—especially among athletes, females and people who follow vegetarian or vegan diets.

Not enough iron in the bloodstream leads to a range of health concerns, including poor sleep and fatigue, and although it is essential for good health it is not produced naturally by the body—food is our primary if not only source of iron.

Read on to find out more about why iron is so important to overall health, and how to optimise your iron intake by adjusting your eating habits.

What is iron?

About 70 per cent of the body's stores of iron are found in red blood cells (haemoglobin), which transport oxygen in the blood from the lungs to tissues, and is also found in muscle cells called myoglobin that transport oxygen to the muscles. Iron is also involved in other essential functions such as immune function, enzyme production, collagen synthesis, cognitive function and energy production. When stores of iron in the body are depleted, this results in iron depletion, with further losses leading to iron deficiency anaemia.

Why is iron so important?

When there isn't enough iron available in the bloodstream, haemoglobin production is limited, resulting in poorer oxygenation of tissues in the body. This can lead to symptoms such as poor concentration, poor sleep, weakness and fatigue as the tissues and muscles do not have enough oxygen to be able to function optimally. Iron is not made in the body so has to be consumed from the food we eat, so our diet is the key factor to consider when we are looking at optimising our iron levels in the body.

Who is most at risk of iron deficiency?

Females have a higher risk of developing iron deficiency than males due to losses of iron through menstruation, in particular females with heavy periods or blood clotting.

Athletes or people with high activity levels are also at a high risk of iron deficiency. Regular exercise stimulates the production of red blood cells which requires iron for the haemoglobin component, but if food intake isn't meeting the increased demands then deficiency can occur.

Runners in particular are more prone to low iron thanks to foot-strike haemolysis (sometimes known as runners anaemia) which occurs when red blood cells (and the iron attached to these cells) are damaged with the repetitive pounding of feet on hard surfaces.

People following vegetarian or vegan diets are also at a higher risk of deficiency if their diet is not optimised to meet iron requirements. Iron through animal-based foods is absorbed more efficiently in the body than plant-based foods, but that is not to say that a vegetarian or vegan diet can't meet iron requirements through food with some careful planning!

Iron deficiency can also be caused by a lack of absorption in the body rather than poor iron intake from food. The small intestine absorbs all nutrients within the body. An intestinal disorder, such as coeliac disease may prevent adequate absorption of iron, potentially leading to iron deficiency. 

Iron deficiency is common for pregnant women without supplementation. This is due to the combination of both increase in blood volume seen in pregnant women, as well as the additional iron that is needed to help grow the baby. 

What are some ways to optimise iron in our diets and prevent deficiency?

As you can see, iron deficiency can occur for a number of reasons, and isn't necessarily caused by a lack of iron in the diet. However, when we look at these factors that increase risk of iron deficiency, it's easy to see why we need to optimise iron in our diets to help prevent deficiency.

Here's how to optimise iron in your diet to prevent iron deficiency:

1. Consume foods that contain iron: There are two types of iron in food—haem iron and non-haem iron. Haem iron is found in animal-based foods such as meat, poultry and seafood, particularly red meat—the redder the meat, the more iron it contains. Australian Dietary Guidelines recommend red meat intake be limited to small portions, while focusing on poultry, seafood or plant-based proteins at other meals. Haem iron is more efficiently absorbed in the body than non-haem iron which is found in plant-based foods such as legumes, tofu, some nuts and seeds, kale, broccoli, wholegrain cereals and dried apricots. Aim to include a range of all these foods in your diet on a daily basis to ensure you are getting enough iron in. If you are following a vegetarian or vegan diet, including these non-haem iron sources regularly is essential to maximise absorption in the body.

2. Consume foods that contain vitamin C at the same time as you consume foods that contain iron: Vitamin C helps iron absorption in the body when consumed at the same time. Consuming foods that contain vitamin C at the same time as non-haem iron sources is essential to get as much iron absorption as possible! For example, eating fruit or vegetables with your tofu or legumes can help the body to absorb more of the non-haem iron in these foods.

3. Avoid consuming calcium-rich foods at the same time as iron-rich foods: If you can, avoid eating calcium-rich foods such as yoghurt, milk and cheese at the same time as your iron-rich foods where possible, as calcium inhibits iron absorption in the body and is best consumed separately as each are important nutrients that support good health. This is particularly important to consider if you have been diagnosed with iron deficiency, as foods high in tannins also inhibit iron absorption, including teas, coffee and red wine, so it is better to stick to having these in between meals.

If you feel that you have the symptoms mentioned above for iron deficiency, see your doctor for a blood test before taking action with an iron supplement as it is possible to over-do it with a supplement. If you are someone with increased risk factors, such as females, highly active individuals or athletes, are following a vegan or vegetarian diet or have a digestive condition such as Coeliac disease, follow our steps to optimise iron in your diet. Aim for a balanced diet with a variety of haem and non-haem iron foods and plenty of fruit and vegetables to help increase iron absorption. 

Always seek the guidance of your doctor or other qualified health professional with any questions you may have regarding your health or a medical condition.

Explore more content like this in our series, Ask a Dietitian.

Health & Performance Collective is the brainchild of Sydney Dietitians Jessica Spendlove and Chloe McLeod. They use their 20 years of combined knowledge and skills as dietitians to work with motivated people to live and perform at their best.

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