You've heard it 10000x - you need iron to run well. But do you actually know why? Or how much iron? Or where to get it, especially if you don't eat red meat?
Iron deficiency anaemia is the world's most common nutritional deficiency disease. It's of particular importance to female runners for it's role in energy production.
What is iron?
There are 2 major pools or iron in the body: (1) functional iron in proteins include haemoglobin, myoglobin, cytochromes and enzymes; (2) storage iron in ferritin, hemosiderin, and transferrin (you'll see these names if you ever get a blood test to check your iron levels).
What is the role of these proteins in the body?
Functionally, iron allows these proteins to bind to oxygen. Oxygen is key in aerobic energy production eg any low intensity movement.
Both haemoglobin and myoglobin transport or store oxygen. Haemoglobin is a blood protein and transports oxygen around your body. Myoglobin are proteins located within your muscle. These proteins store oxygen in your muscles as a reservoir for when your blood oxygen levels are low eg exercise.
As your body is in need of energy, it calls upon cytochromes and iro-dependent enzymes to catalyse a series of chemical reactions that converts chemical energy from the oxygen molecules to ATP energy.
Iron is also required for the production of or to support key players in your immune system eg bacteria, T-lymphocytes, natural killer (NK) cells, interleukin-2. These immune cells enable your body to recognise and get rid of pathogens.
Your brain cells also use iron for normal function. Iron is involved in the function and synthesis of neurotransmitters (important communication chemicals). It is also possible that iron is involved in the production of myelin. Myelin is an insulating casing around your nerves (just like the rubber coating on electrical wires) which speeds up nerve communication.
Transport & Storage - what do your blood tests mean?
Serum iron is a measure of the iron in your blood
Serum ferritin is a measure of your iron stores as iron is stored within ferritin. Your body will tap into it's stores if your blood levels get too low.
Transferrin saturation shows the percentage of transferrin in your blood that is attached to iron. Transferrin is a protein that transports iron through your body.
So how much iron do you need?
Women: menstruating women require a higher iron intake due to the significant amount of iron lost during menstruation.
Growth: physical and behavioural development of children is dependent on iron intake. It's important to ensure that children and young people are meeting their iron requirements.
Pregnancy: Growing a new human requires a significant increase in iron intake due to the increase in haemoglobin production. This allows adequate blood supply to the mother and the child.
What can impact your iron needs?
What happens if you don't get enough iron?
If you aren't meeting your bodies iron requirements you may suffer from symptoms related to inadequate oxygen availability such as tiredness, light-headedness, dizziness, build up of lactic acid, poor concentration and early fatigue in training.
Iron also impacts your immune function. Both excess and inadequate iron can cause issues for your immune system. The production of a number of your key pathogen-fighting cells decreases with iron deficiency. This can put you at increased risk of infection. As an athlete, every training session matters. You can't afford to continually be getting sick and missing out on sessions or competitions.
In terms of brain function, deficiencies have been found to result in differences between learning, memory and concentration - not the greatest when you need to concentrate on the field.
So how do you make sure you're getting enough?
There are 2 types of iron found in foods, haem and non-haem. Haem iron is best absorbed by your body and is mostly found in red meats eg beef and lamb and to a lesser extent some of your lighter meats. Non-haem iron is found in your plants eg fortified cereals, baked beans, potato skin etc.
When consuming non-haem iron, make sure that the iron is paired with a source of vitamin C eg orange, kiwi fruit, capsicum as vitamin C helps your body to absorb this form of iron. On the other hand, there are many food-parts that can also negatively impact absorption by either binding to the iron molecule or competing for absorption. Phytates (eg found in legumes and grains), zinc and calcium will inhibit both haem and non-haem iron. Polyphenols (found in vegetables, berries, teas and coffees) and vegetable protein can inhibit absorption specifically of non-haem iron.
Good food sources of iron: