Anaemia: When fatigue takes over


Today I am going to talk about the number one deficiency in general and especially amongst female athletes of all sports particularly runners, Anaemia. Anaemia is something that can occur slowly but can have significant effects on your day-to-day life as well as athletic performance.

What is Anaemia?

There are many different types of anaemia and each has it’s own set of reason for why you might develop it. The most common type of anaemia is iron-deficient anaemia. Other types of anaemia can stem from other mineral deficiencies like Vitamin B12 and folate acid.

Iron is an essential part of the make up of a protein in the red blood cells. Anaemia is when you don’t have enough iron in your body causing you to have fewer red blood cells to carry oxygen. The function of iron is to produce red blood cells, which carry and store oxygen to travel to all the organs and muscles of the body. It is also vital for normal growth, development, cellular function and the processing of different hormones not to mention the health of connective tissues like tendons and ligaments.

If you are low on iron you therefore will be low of oxygen. One way to look at it is like having a hole in your fuel tank in the car, you can fill it up but more often than not it will be running with a warning light. You will literally be going running on limited or no fuel excuse the pun.

The daily recommended iron levels are the following:

Daily recommended iron amounts

12mg is normally considered to be anaemic for women and children whereas 13mg is for men.

Why do you get anaemia?

As previously stated there are many different types of anaemia and therefore many different reasons why you can develop it in the first place and some can be very serious.

The most common cause of anaemia is bleeding within the stomach and intestines this can be for several reasons including stomach ulcers, cancer of either the stomach or bowel. As with many other conditions medications can be a reason including taking NSAIDs which include ibuprofen, naproxen and aspirin to name a few very common ones.

People at risk of iron deficiency:

  • Pregnant women
  • Infants and young children
  • Women with heavy periods
  • Blood donors
  • Cancer patients
  • Patients suffering from stomach conditions and heart failure
  • Athletes particularly women

When you are pregnant your body needs more iron for the development of the baby. If you have low iron during your pregnancy you can be at risk of premature births, as well as cognitive and behavioural issues

Obviously during your period you will be losing blood and therefore iron which is why that can be an obvious cause. The average iron loss when you are on your period is around 5-45mg depending on the length and rate of flow.

Diet and Iron

Unless you are pregnant or for some reason need more iron than the average person it is unlikely that your diet will be the sole cause for anaemia. Iron can be found in many different foods and is actually purposely added to many grains.

There are two different types of dietary iron one is haem iron, which is from animal sources, and the non-haem iron from other sources. Haem iron is better absorbed with the uptake around 40% around 20% more than non heam. This is due to the iron not needing to bind to any proteins in order to be absorbed. In non-haem iron products they need to be broken down into ferrous iron first before being absorbed therefore the uptake it much less. Another problem with iron absorption is that on average only 15% of the iron you get from your diet is absorbed, so if you are anaemic it may take a while for your levels to normalise. (Hurrell 1997)

Good sources of iron include:

  • Leafy green veg like: Kale or spinach
  • Cereals and bread (they often have iron added to it and 50% of the population get their daily amount this way)
  • Brown rice
  • Nuts and seeds
  • Meat, fish and tofu
  • Eggs
  • Dried fruit.

Another aspect that can help the absorption of iron is to make sure that you are getting enough Vitamin C it is very common for patient to take iron tablets with orange juice for this reason.

There is also many different food that’s will reduce the absorption of iron these include:

  • Tannic acid (Tea + Coffee)
  • Calcium (Dairy products including milk, yogurts
  • Additives (soft drinks and fast and convenient foods)

What are the symptoms?

The symptoms for anaemia are generally hard to pick up, as often you will put it down to a cold or simply being run down. Athletes may pick up symptoms quicker due to pushing their body to the limit and therefore increasing the amount of oxygen that they need.

Here is a list of symptoms:

  • Tiredness and lack of energy (lethargy)
  • Shortness or breath
  • Dizziness or light-headedness
  • Muscle cramps or soreness
  • Nausea
  • Stomach pains including diarrhea and constipation.
  • Palpitations or being able to feel your heart beat
  • A pale complexion with pale eye sockets

Less common symptoms include:

  • headache
  • frequent infections
  • Sleep deprivation
  • Tinnitus or ringing in the ears.
  • An altered sense of taste
  • Feeling itchy
  • Sore or smooth tongue
  • hair loss
  • Pica: A desire to eat non-food items, such as paper, ice or sand
  • Dysphagia: Trouble swallowing
  • Mouth ulcers particularly in corners of your mouth they can be painful
  • spoon-shaped nails


If you are worried about anaemia you should consult with your GP and get a blood test. Luckily it is relatively easy to diagnosis and often picked up as a routine assessment. You can also do a quick home test, if you pull down your eyelid you should see a pink lining of the eye socket if it is pale in colour this may indicate if you are anaemic. Obviously this is not a conclusive test and you should definitely go see your doctor, there can be some very significant consequences of iron deficiency otherwise.

There are three different stages of anaemia. The first two stages are often grouped together and are called pre-anaemic latent iron deficiency.

Stage 1: Iron storage depletion

It is common during the first stage for the condition to go undiagnosed even for several months. At this stage you will have less iron stored in the cells of your liver, spleen and bone marrow and have an overall fall in serum ferritin. The iron going round your body at this stage shouldn’t be significantly affected.

Stage 2:

At this stage the amount of iron transported throughout your body will fall, therefore the overall amount of iron will too. You will have low serum iron and a lower concentration level. The body should react and try to increase the about of iron that you would normally absorb. In Stage 2 the red blood cells and oxygen will be reduced enough to affect your atheletic performance.

Stage 3: Iron deficiency Anaemia

At stage 3 you will get experience extreme fatigue with it affecting your physical ability not only in terms of athletic performance but the ability to function and complete day-to-day activities. At this stage it will be very obvious from the blood results that you are suffering from anaemia.

To diagnosis anaemia your doctor or GP will do several different blood test. They will be looking at different biochemical indicators of iron but also for Vitamin B12 and folate levels. Here are some for the normal levels for iron:

Table 1. Biochemical Indicators of Iron Status
Ferritin The storage form of iron. Females: 12-150 ug/dl

Males: 15-300 ug/dl

Iron A trace mineral necessary for replacing red blood cells that are destroyed in body processes. Vitamin C enhances the absorption of iron. Females: 60-160 ug/dl

Males: 80-180 ug/dl

Hematocrit The volume percentage of red blood cells in the blood. Females: 33-47%

Males: 39-54%

Hemoglobin A protein found in blood that aids in the transportation of oxygen to various tissues Females: 11.5-15.5 gm/dl

Males: 14.0-18.0 gm/dl

What is the treatment?

Another reason why you should go to your GP rather than self-diagnosis and treat is that they medication you will receive can be very different. The bog standard over the counter iron supplement from pharmacists normally has about 14mg of iron in them. The main tablet the GP will prescribe will be ferrous sulfate, the doses can vary from 50-200mg of iron and depending on your levels you could be taking it 2 or 3 times a day. Therefore if you are at stage 3 you could be prescribed 600mg a day that’s a huge difference to just 14mg. There are many side effects of iron supplementation, which is why it should be monitored closely you will mostly have to get the blood repeated every month. It can be just as serious to have not enough iron compared to too much. Also you can be advised to increase the iron table dosage slowly due to the side effects associated with it.

Complications if left untreated:

A word of warning while the symptoms of anaemia can seem relatively ambiguous they can have serious health consequences. If you leave anaemia untreated it can affect your heart and cardiovascular system. A lack of iron can also affect your immune system and make you more susceptible to infections and affect your immune system in general.

The effects of your cardiovascular system can be very serious with patients being more at risk for conditions like angina, tachycardia (abnormally high heart beat) and can eventually lead to right sided heart failure. Angina is when you get a pain or heavy feeling in your chest, which can refer down your arm, neck or jaw.

Anaemia and exercise:

Anaemia is the most common deficiency in athletes, military personnel with it being particularly prevalent in runners. A shocking 50% of all endurance athletes across all sports have below normal iron levels. (Beard & Tobin 2000) Therefore it is important that female athletes take note of their iron levels and monitor them regularly. While it is generally female athletes that are affected the most a new study looking at anaemia in triathletes and runners showed it was actually more prevalent in men than women.( Coates et al 2016)

Furthermore active individuals will also be more aware as they are pushing their body to the extremes and therefore will notice the lack of energy soon. Often active individuals will notice that their performance will suffer or they just cant keep going for no apparently reason, they know they are fitter but they still cant complete the session as well as they would have done previously.

There is some research to show that intense or overtraining may contribute to loss of iron through the symptoms are more short term than other types of anaemia. The theory with intense/overtraining is that the constant increase in inflammatory levels in the blood will affect your levels of iron. While the daily-recommended amount of iron is normally 15mg for endurance athletes Colgan et al 1991 states you may need iron levels as high as 41mg. Therefore it can take up to 8 weeks to restore your endurance back up to your normal level after being anaemic however you should feel the benefits sooner. (Rowland et al 1988) However there is no recommendation that athletes use supplements for iron.

It is worth baring in mind it maybe harder for athletes to get the additional iron for optimal performance through their diet alone.

There is some research and speculation that repeated foot contact when running can cause your red blood cells to rupture and release haemoglobin, which gets excreted through your urine via your kidneys. It speculated by Clarkson & Haymes, 1995 that up to 1-1.5mg can be lost in this way. There is also evidence you can loose iron through sweat however this is a very negligible about of around 0.3-0.4 mg per litre so is very unlikely it will cause you to have anaemia. (Waller & Haymes 1996)

How does a reduced amount of iron affect your performance?

The exact impact of iron deficiency on athletic performance is still debatable in research. (Alauntye et al 2015) However this is what some of the research is suggesting:

A reduced iron level can increase your overall timings for running as well as you’re perceived effort, overall strength and cognitive state. McClung et al 2009 showed that after a course of iron supplements in deficient soldiers the time it took to run 2 mile was 2 minutes faster!! This is a significant difference. When you are iron deficient you will be unable to recovery between sets and bouts of exercise. Your general performance and strength may be effective in general. You will also experience fatigue and be unable to continue at the same pace or effort as you were previously able to without occurring symptoms. If you continue to train hard in an iron deficient state you are at more risk of developing an overuse injury, as your body is unable to adapt and recovery quick enough.

Therefore it is not surprising that in some research the sports that are affected most by anaemia and reduced iron are sports that require both cardiovascular and power.

Anaemia in different sports

The overall message is if you are worried about being anaemia go and get it check out by your doctor the testing is very simple but it could provide a lot of answers!!



When fatigue slows you down iron deficiency anaemia Mueller.

Rowland TW, Deisroth MB, Green GM, Kelleher JF. The effect of iron therapy on the exercise capacity of nonanemic iron-deficient adolescent runners. Am J Dis Child. 1988; 165-169.

Clarkson P, Haymes EM. Exercise and mineral status of athletes: calcium, magnesium, phosphorus, and iron. Med Sci Sports Exerc. 1995; 27: 831-843.

Beard J, Tobin B. Iron status and exercise. Am J Clin Nutr. 2000; 72(2): 594S-597S.

Hurrell RF. Bioavailability of iron. Eur J Clin Nutr. 1997; 51: S4-S8.

Colgan M, Fielder S, Colgan LA. Micronutrient status of athletes: Calcium, magnesium, phosphorus, and iron. J Appl Nutr. 1991; 43: 16-27.

Waller MF, Haymes EM. The effects of heat and exercise on sweat iron loss. Med Sci Sports Exerc. 1996; 28: 197-203.

Alaunyte, I., Stojceska, V., & Plunkett, A. (2015). Iron and the female athlete: a review of dietary treatment methods for improving iron status and exercise performance. Journal of the International Society of Sports Nutrition, 12, 38.

McClung JP, Karl JP, Cable SJ, Williams KW, Nindl BC, Young AJ, Lieberman HR. Randomized, double-blind, placebo-controlled trial of iron supplementation in female soldiers during military training: effects on iron status, physical performance, and mood. Am J Clin Nutr. 2009 Jul;90(1):124-31.

Iron Dietary Supplement Fact Sheet: National Institutes of health:


Coates A, Mountjoy M, Burr J. Incidence of Iron Deficiency and Iron Deficient Anemia in Elite Runners and Triathletes. Clin J Sport Med. 2016 Sep 5. [Epub ahead of print] PubMed PMID: 27606953.

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