What is iron?
Iron is a mineral found in the body and forms a key part of haemoglobin, the protein found in red blood cells that is responsible for carrying oxygen from the lungs to the rest of the body.
How much do we need?
Iron requirements vary depending on age, menstrual status and most likely training volume and environment too. The current UK guidelines state Reference Nutrient Intakes (RNI) of 8.7mg/day and 14.8mg/day for males and females respectively. Female recommendations fall to 8.7mg/day following menopause. Further details can be found here:
How does iron help runners?
The main function of iron, as you probably guessed, is to help with oxygen transportation from the lungs to wherever it is required. Being predominantly aerobic beasts, this suggests that keeping on top of your iron levels should be a regular priority for runners, especially females, vegetarians and those athletes training twice a day or on high weekly mileages.
We lose iron in a number of ways: Haemolysis is the loss of red blood cells through impact or exercise intensity, certainly common for the pavement pounders amongst us! We also lose small amounts of iron through sweating, and display an increased need for iron when training or competing at altitude. Ultra-endurance or marathon runners may also show signs of gut damage, and this too can affect iron levels and stores.
Where do we get iron?
We store very little iron within our blood, suggesting we need a consistent supply of iron from our diet. Iron is also poorly absorbed by the body (15% from meats, 7-8% from plants), again suggesting a steady supply of iron is best for us. Offal, game and red meat are typically considered the best sources of iron, with dark green leafy vegetables, dried fruits and fortified cereals being plant-based sources.
Can I do anything to help my absorption of iron?
Yes! Vitamin C helps with the absorption or iron, so consider dressing meat or vegetables with a squeeze of citrus (orange, lemon or lime) juice. Whilst Copper (yes, another metal) helps get the iron to the bone marrow, where red blood cells are produced. B-vitamins are also important for red blood cell production, and these are often found in fortified cereals, red meats, or as a supplement complex.
The timing of iron rich foods or supplements may also be important: avoid eating iron rich foods, or supplementing close to exercise or after a coffee. We say this because hepcidin (a hormone released after exercise) and caffeine (found in coffee and tea) both interfere with the absorption of iron.
An iron rich day
As a working example, the following would provide ample iron for a recreational runner, with healthy iron stores:
Breakfast: Fortified cereal, glass of orange juice (iron: 6.0mg)
Snack: 3 digestive biscuits (1.6mg)
Exercise: Lunchtime run of 30-40 minutes at an easy effort level
Lunch: Jacket potato, beans and salad (6.3mg)
Snack: 4 dried figs (3.2mg)
Dinner: Spaghetti Bolognaise (4.8mg)
Please note that this is in excess of the RNI. This is to account for inefficiencies in intake, possible haemolysis and losses through sweat or urine. But, see how easy it was to meet the recommended intake?