Iron Defficiency and Endurance Athletes

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January 12, 2017

D3 Staff


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Every endurance event is a challenge beginning with your training and being able to make it to the starting line 100% healthy.  Throughout your training you may come across constant fatigue (abnormal amounts), increased heart rates during exercise that (abnormal from typical training), and even become more irritable than usual.  The immediate diagnosis is probably dehydration, under fueling or overtraining.  As you make those adjustments to accommodate your self-diagnosis the problems still occur.  One overlooked problem could be coming from one of the most abundant metals on earth, which oddly enough is also one of the most common disorders nutritionally iron.Iron is essential for human physiology as it is necessary for hemoglobin and myoglobin proteins, which are vital for transport of the oxygen in the blood and muscle.  It also is critical for functionality for your immune system and brain.  As you would imagine the facilitation of exercise and your performance will be affected by your iron levels.   If too little iron is available, smaller or even fewer red blood cells will be produced which will lead to less oxygen being transported in the blood.  If this is what is occurring, then the symptoms mentioned could possibly be an iron deficiency identified as anemia.

As an endurance athlete you are constantly testing your body's limit daily and rely on the delivery of oxygen to your muscles to allow for this to happen.  If you are slightly anemic, you may see some detrimental effects on your training performance.  Since iron is an essential nutrient, you need to get it from your diet since your body is not able to synthesize it.  As mentioned previously, iron deficiency is a worldwide common deficiency and happens when your dietary intake does not meet the needs of your body.  This won't occur suddenly but when you are deficient it happens in consecutive stages.

Initially in the first stage iron depletion will occur when the iron that is stored in your bone marrow becomes depleted.  This is the most common stage that is seen in athletes. The next stage will happen with continued depletion of iron.  During this 2nd stage, hemoglobin synthesis will become where you develop a deficiency of iron.  The last stage is when you are considered to be anemic, which is what develops when your iron stores are inadequate to maintain hemoglobin production, which also results in a reduced mean cell volume.

Endurance athletes have shown they usually have a high loss of iron and will typically have large requirements.  With all of the constant training and competitions you are sweating a great deal, and to cool yourself down the body produces sweat.  As you sweat you are also losing some iron.  Women athletes that are menstruating are at risk due to the blood loss during their menstrual cycles.  Vegetarian athletes are another group that is at a higher risk for iron deficiency due to their plant based diets. Typically since you are training so much you fuel on mostly carbohydrates.  That is good but carbs don't offer the best bioavailability of iron which is more abundant in protein sources.  Iron in your diet will come from two possible forms being "heme" or "non-heme".  The heme iron will be located in more protein based sources such as meat, fish, and poultry.  The non-heme form is what you see in the carbohydrate sources such as fruits, vegetables, breads, etc.  The easier of the two to be absorbed by your body is the heme version of iron.  Something to consider is that consuming vitamin c rich foods or drinks may aid in absorption of iron.  However, another thing to consider is that drinking teas or coffees could inhibit the absorption of iron.

If you are deficient in iron, supplements help but don‚'t really address the issue.  Typically that is because it is your diet that needs some work.  Work with a nutritionist/dietician when possible to help make sure you are getting enough iron in your diet.  If you can prevent a deficiency from happening to you, it is obviously the best course of action.    You should also consult with your physician who can see through a blood test to confirm that iron levels are the problem.  The physician will see if you have a low hemoglobin level while also testing to see what your blood ferritin level is.  Ferritin is the protein that will attach to iron that is in your blood.  When you have a low ferritin level it is possible that it means your iron stores are low and could be leading to an iron deficiency.

Overall, with endurance activities iron deficiency risk increases as does the possibility of your performance decreasing.  There have been a few studies suggesting that a male endurance runner will need 17mg per day to meet their iron needs while a female would need about 23mg per day.  Remember that not just menstruating women and vegetarian athletes are at risk.  The athletes that are not having an appropriate diet or that are on a calorie restricted diet can lead to anemia.  Iron supplementation has been common in endurance sports and will help those who are anemic improve their performance.  There is a risk of having too much iron which could damage some vital organs, so remember to consult with your physician if supplements are for you


Clark, SF. Iron Deficiency Anemia. Nutr Clin Prac.  2008; 23: 128:141.

Fallon, KE.  Utility of hematological and iron-related screening in elite athletes.  Clin J Sport Med. 2004 May;14(3):145-52.

Suedekum NA, Dimeff RJ.  Iron and the athlete.  Curr Sports Med Rep.  2005; 4(4): 199-202.

Zoller H, Vogel W.  Iron supplementation in athletes:first do no harm.  Nutrition. 2004; 20: 615-619

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