Having a robust store of iron is critical for optimal endurance performance and yet it is one of the most common nutritional deficiencies seen in endurance athletes.

Iron is important to the endurance athlete due to it’s key role in both energy production and oxygen transportation to the muscles. The average adult body contains about 4 grams of iron, mostly within the two proteins haemoglobin (found in red blood cells) and myoglobin (found in muscle tissue). If these levels become depleted an athlete is at a higher risk of a decline in both training capacity and performance.

Maintaining optimal iron levels through diet is essential for every endurance athlete as they are at a higher risk of iron deficiency (anaemia) compared with the general population. This is due to an imbalance between exercise-induced iron loss and the absorption of dietary iron. However, three groups of athletes are at a particular high risk of anaemia.

Groups of Athletes at Most Risk of Anaemia:

  1. Runners & triathletes: These athletes are more prone to low iron levels than non-athletes, due to a condition called foot strike hemolysis. This is where red blood cells (the cells, which transport the iron rich haemoglobin around the body) are destroyed through the impact of the foot repetitively striking the ground, leaving the athlete with a depleted store of iron.
  1. Female athletes: Female athletes are at a higher risk of iron deficiency due to the depletion of haemoglobin through the loss of red blood cells during their monthly period. The heavier the blood loss the more at risk they become. It is recommended that all female endurance athletes increase their iron rich food intake during their menstruation.
  1. Vegan and Vegetarian athletes: Maintaining ideal iron levels isn’t simply a matter of eating an abundance of iron rich foods. It’s also influenced by how much of that iron is absorbed into your bloodstream. Although there are many health benefits of a plant-based diet, one way a vegetarian or vegan diet is inferior to a meat-based one is through the bioavailability (ease with which the body absorbs and utilises) of iron. Iron from meat is already linked to haemoglobin (called heme-iron) and is more easily useable than the plant form of iron, which is non-heme (not linked to haemoglobin).

In fact vegetarian & vegan athletes often eat a more iron rich diet but have lower levels of iron due to the lower bioavalibility of non-heme iron. However, aside from in the very severe cases of anaemia, vegetarians and vegan endurance athletes do not need to switch to a meat-based diet to maintain an ideal iron level. Instead by consuming a higher volume of non-heme iron (1.8 times heme-iron) and by following our top tips below, even those athletes at a higher risk of anaemia can optimise their iron levels

Maximising your iron absorption:  

Optimising iron levels isn’t always as simple as eating more iron rich foods, especially if you are vegetarian or vegan. Follow these top tips to maximise the bioavailability and absorption of the iron you eat:

  1. Eat non-heme foods with foods rich in vitamin C: Research has shown that by adding vitamin C rich foods to iron rich foods you can increase the absorption of iron by up to 5 times. Add peppers, oranges, tomatoes, berries, orange juice and dark green leafy vegetables to your high iron meals.
  1. Consume iron rich foods away from intense training sessions: Your ability to absorb iron can be reduced after exercise, so to maximise your iron absorption wait a minimum of 2-hours after intense exercise to consume any iron rich foods.
  1. Avoid food which block the absorption of iron: Certain food groups interfere with the body’s absorption of iron. If you struggle with low iron levels avoid these foods completed otherwise only consume away from iron rich foods.
    • Coffee (including de-caff)
    • Black tea
    • Dairy
    • Supplemental fibre
    • Supplemental calcium
  1. Avoid foods high in oxalates: Food high in oxalates also block the absorption of non-heme iron. Oxalates are compounds derived from oxalic acid and are found in the below foods. Spinach is an interesting case, as although it has a high level of iron, very little is absorbed by the body due to it’s high levels of oxalates, making it a poor choice for vegetarians or vegans.
    • Spinach
    • Dark chocolate & cocoa
    • Raspberries
    • Beetroot
    • Nuts and seeds
    • Rhubarb
    • Beans
    • Black tea
    • Wheat bran
    • Potatoes
    • Buckwheat
    • Swiss chard
    • Tofu, miso and other soya foods

Recommended daily intake of iron:

Meat eaters: At least 18mg/kg/day
Vegetarian/Vegan: 32mg/kg/day
Meat Eaters: At least 8mg/kg/day
Vegetarian/Vegan: 14.4mg/kg/day

Meat sources of iron:

Although all meat contains heme-iron the best sources are from liver and other organ meats. If offal is not something that you can stomach, go for beef, lamb or venison.

Vegetarian Sources of iron:

Dried apricots, red lentils, beans, brown rice, pumpkin seeds, prunes, chickpeas, wholemeal bread, cashew nuts and broccoli

Symptoms of iron-deficiency:

Below are common symptoms of iron deficiency. If you are experiencing 3 or more of these symptoms please visit your doctor.

  • Fatigue
  • Muscular weakness
  • Increased heart rate during exercise
  • Pale skin
  • An inability to maintain body temperature
  • Light headedness
  • Shortness of breath
  • Dry or damaged hair & skin






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