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Lisa is an Advanced Sports Dietitian, fitness consultant and co-author of Eat For Your Life. She is based in Melbourne.
Do you feel tired all the time? Do you always feel run down and suffer from frequent colds and infections? Do you find it hard to recover from sessions? Do you feel like you need more energy to train and perform at your best? You could be low in iron.
Iron is essential for everyone, especially so if you are training. Athletes may need more than 50% more iron than someone not training. Females are more likely to become iron-depleted, however males who train are also at risk. Without enough iron, your body will find it difficult to function at its best.
Inadequate dietary iron intake can lead to depleted iron stores, or may lead to iron deficiency anaemia.
Iron is an essential component of hemoglobin, found in red blood cells, which carries oxygen from the lungs around the body to the muscles and brain.
If iron levels are inadequate, this can lead to low hemoglobin levels and subsequent fatigue.
Hemoglobin is a marker often used to determine the level of iron depletion in the body.
Iron will also influence energy systems and immune function, which doesn’t help when you’re trying to get through your weekly training program.
Fatigue is the main symptom associated with low iron levels. Other symptoms include:
Regular training can lead to exercise-related iron losses. Iron can be lost through sweat and can also be lost via the gastrointestinal tract. You can even lose iron through ‘foot strike’ impact, which can damage red blood cells.
More blood cells are produced with any type of heavy training, which in turn increases the need for iron. Anecdotally, I find that endurance-type athletes, male and female, are most prone to low iron levels. The assumption would be that more red blood cells are produced with aerobic activity, where the oxygen-carrying capacity requirements and damage to red blood cells may be higher.
Haem iron is found in animal sources such as meat, seafood and chicken, and it is more easily absorbed than the non-haem iron found in plant sources such as green vegetables, nuts, legumes, tofu, fortified breakfast cereals and wholegrain bread. The best way to ensure you meet your iron needs is to eat red meat regularly, in combination with other iron-rich foods. The table below indicates common foods and their iron contents.
Liver 100g 11mg
Beef 150g 5.7mg
Kangaroo 150g 3.9mg
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
If you don’t eat meat regularly or at all, then careful planning is required to maximise iron absorption from foods.
The first step is to eat more foods that are rich in iron and to plan meals, snacks and fluids to optimise absorption. You can combine non-haem iron with a haem source in the same meal will enhance absorption of iron from the non-haem source. Vitamin C may also enhance absorption of non-haem iron. Foods rich in Vitamin-C include strawberries, kiwifruit, citrus fruits, tomatoes, broccoli, cauliflower or red capsicum. So try food combinations such as:
broccoli and cauliflower added to a tofu stir-fry
Note that strong tea and coffee contain tannins that can impair absorption of iron, so we recommend you avoid having these with a meal. Cola-based drinks may also affect absorption of iron.
Emerging evidence shows that the timing of iron intake will influence the amount your body absorbs. After exercise there is an increase in the activity of hepcidin, a hormone produced by the liver that may decrease iron absorption. The research in this area is new, so there are no definitive recommendations as yet. We know that you would still absorb some of the iron from taking iron supplements or eating an iron-rich meal soon after exercise, but some absorption may be impaired. So if you train in the morning, then perhaps try to get plenty of iron later in the day, and if you train in the evening then boost your iron at breakfast.
There are many factors that contribute to fatigue, iron is just one of them. Iron supplements may be recommended if a blood test shows your iron levels are low, however there are significant risks associated with taking an iron supplement just because you feel a bit tired. Excessive iron can impair the absorption of other minerals such as zinc. More seriously, haemochromatosis is an often undiagnosed genetic condition (more common in males) where iron levels are elevated regardless of diet, so additional iron can be dangerous. Often there are no symptoms until it is quite serious (e.g. liver disorders, impaired memory and mood swings), and the onset of general fatigue and lethargy may be mistaken for iron deficiency. This is why you should never just take an iron supplement without a blood test. Results really should be interpreted by a health professional, as there are a range of markers measured when a blood test is done.
If you do have low iron levels, see an Accredited Sports Dietitian to ensure you are maximising dietary iron intake and absorption and to determine whether you need a supplement. Most people don’t need to continue supplementation once iron levels have increased – just focus on iron-rich foods to improve energy levels and performance.
For more information check out the fact sheet on Sports Dietitians Australia website, IRON DEPLETION IN ATHLETES: