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Advanced Sports Dietitian, fitness consultant and co-author of Eat For Your Life.
Iron deficiency is the natural enemy of the athlete. It can start with poor recovery from training, lead to frequent colds, and infections and leave you feeling constantly rundown and tired.
Iron is a vital part of everyone’s diet – without enough iron, it’s difficult for your body to function at its best. Women are at greater risk of becoming iron-depleted, although men who train are also at risk. In fact, athletes need as much as 50% more iron than someone not training.
Iron is an essential component of hemoglobin, which is found in red blood cells. Hemoglobin is a marker often used to determine the level of iron depletion in the body. Hemoglobin carries oxygen from the lungs to the muscles, the brain, and all around the body. Inadequate iron levels can lead to low hemoglobin levels, which in turn causes fatigue and diminishes immune function.
While fatigue is the main symptom of low iron levels, there are several other warning signs:
Athletes have more ways to “lose” iron than inactive people. Iron can be lost through sweat, the gastrointestinal tract, and even through ‘foot strike’ impact, which can damage red blood cells.
Another factor is that heavy training encourages the production of more blood cells, which leads to an increased need for iron. This happens with any type of heavy training, but anecdotally, I find that endurance athletes tend to be the group most prone to low iron levels. It’s assumed that this is because with aerobic activity, the oxygen-carrying capacity requirements of red blood cells and the damage to them may be higher compared to other types of activity.
Often people play doctor and make iron supplements their first stop when they experience fatigue, but remember that there many factors that potentially cause or contribute to fatigue – iron is just one of them. Taking an iron supplement just because you feel a bit tired has its risks, and excessive iron in the body can be downright dangerous. For a start, it can impede the absorption of other minerals such as zinc. On a more serious level, some people can live many years with undiagnosed haemochromatosis, a genetic condition where iron levels are elevated regardless of diet. There can be dangerous consequences when these people (it’s more common in males) take additional iron, with no symptoms until serious problems such as mood swings, impaired memory, and liver disorders set in. This is why you should leave it to a health professional to interpret your iron levels from a range of markers on a blood test before you take an iron supplement.
If you do have low iron levels, a board certified specialist in sports dietetics (CSSD) can determine whether you need a supplement and help you maximize your dietary iron intake and absorption. Most people don’t need to continue supplementation once iron levels have increased – they just need to eat iron-rich foods and work on a strategy of food combinations to keep their iron levels at a point where their body functions well.
Our body takes iron from what we eat, so inadequate dietary iron intake can lead to depleted iron stores, and even iron deficiency anemia.
There is heme iron and non-heme iron, and ideally you eat a combination of the two. Heme iron comes from animal sources such as meat, chicken, and seafood. This iron is more easily absorbed than the non-heme iron found in plant sources such as green vegetables, legumes, tofu, nuts, wholegrain bread and fortified breakfast cereals. Eating red meat regularly in combination with other iron-rich foods is the most efficient way to meet your iron needs.
Here you can see the iron content of several common foods.
Liver 100g 11mg
Beef 150g 5.7mg
Chicken 150g 1-3mg
Tuna 75g 1.1mg
White fish 150g 0.6-2mg
Oysters 100g 3.9mg
Fortified cereal 30g 2-3mg
Eggs 2 medium 2mg
Tofu 100g 2.5mg
Spinach, cooked 100g 3.5mg
Lentils, cooked 100g 2mg
Almonds 50g 2mg
See more iron-rich foods here.
If you don’t eat meat or at least not regularly, then you need to take more care with your eating strategy in order maximize your iron absorption from other foods.
Optimizing your iron absorption comes down to eating and drinking a wide variety of foods that are sources of iron, and eating foods in combinations that will increase iron uptake.
Plan meals that combine both heme iron foods with non-heme iron foods, as this will enhance absorption of iron from the non-heme food. Complementing your meals with foods rich in vitamin C will help, too, as this may also boost absorption of iron from non-heme foods. Vitamin C is abundant in foods such as tomatoes, citrus fruits, broccoli, strawberries, kiwifruit, cauliflower and red bell peppers. For an iron-packed punch, try food combinations such as:
Just as some foods can improve iron absorption, others can impede it – for example, the tannins in strong tea and coffee (so avoid having these with a meal), and cola drinks may also inhibit iron absorption, too.
The amount of iron your body absorbs is also influenced by the timing of your eating, according to recent evidence looking at hepcidin, a hormone produced by the liver. It appears that this hormone may decrease iron absorption, and its activity increases after exercise. No definitive recommendations have come from this research yet. We know that you would still absorb some of the iron from iron supplements or an iron-rich meal soon after exercise, but your uptake of iron may not be what it could be. It may be better to separate an iron-rich meal from your training by several hours, e.g. if you train in the evening then make sure you eat an iron-rich breakfast.