I strongly advice that you check with your physician if you think your dietary intake of iron is inadequate and are considering iron supplementation.
Iron deficiency is prevalent in distance runners and may impair endurance performance.
“Even with monitoring and treatment in place, iron deficiency and iron deficiency anemia are significant concerns for the health and performance of elite runners and triathletes, and this issue affects males and females.” This conclusion was made in an article published from the University of Guelph (Coates A, Mountjoy M, Burr J. Incidence of Iron Deficency and Iron Deficient anemia in Elite Runners and Triathletes. Clin J Sport Med. 2016 Sep 5.)
The most common symptom of all types of anemia is fatigue (tiredness). Fatigue occurs because your body doesn’t have enough red blood cells to carry oxygen to its many parts.
Anemia also can cause shortness of breath, dizziness, headache, coldness in your hands and feet, pale skin, chest pain, and weakness.
Iron deficiency anemia arises when the balance of iron intake, iron stores, and the body’s loss of iron are insufficient to fully support production of red blood cells.
A combination of the following factors are often argued to place athletes at risk of iron deficiency:
There are lot of arguments about which are the main cause of iron deficiency in athletes. New research seems to have found a more plausible explication.
Iron is an important element for human health, as it makes up the heme molecules of hemoglobin, which carries oxygen within red blood cells (the amount of iron in the human body is not large—approximately 4.0 g in a typical adult male). It is necessary for athletes to have sufficient hemoglobin in order to perform at the highest level. In fact, oxygen carrying capacity through hemoglobin is so important for performance that athletes use altitude tents, or train in hypoxic environments, in order to stimulate greater production within the body.
Structure of human hemoglobin.
The proteins alfa and beta subunits are in red and blue,
and the iron-containing hemegroups in green.
Illegal exogenous methods, such as EPO or blood doping, also aim to achieve the same effect – namely increasing the amount of oxygen that can be unloaded at the muscles, thereby increasing the athlete’s ability to work aerobically.
As mentioned above it has been argued that anemia (deficiency of red blood cells) in athletes was caused by: “foot-strike hemolysis” or intravascular hemolysis in which red-blood cells are essentially crushed from running or other exercise-related trauma. However, iron is not technically lost in these cases, and the body is capable of recycling that iron to form new red blood cells. So I find it little convincing that this can cause iron deficiency.
Other causes may relate to a lack of blood flow to the gut during intense exercise, possibly along with non-steroidal anti-inflammatory drug use, causing small wounds (ulcers) in the stomach with some bleeding . Other minimal mechanisms include loss of iron through sweat and urine. However, despite the fact that these forms of iron-loss are certainly occurring, it dosen´t necesaryly explain that these forms can clarify the extent to which endurance athletes have iron deficiency or iron deficiency anemia.
It’s obvious that inadequate supply of dietary iron is a cause of iron deficiency, but despite sufficient and healthy diet there still are athletes suffering of various grades of iron deficiencies.
New research suggests that one of the most important causes of iron deficiencies in athletes may be due to impairment to iron absorption rather than iron loss. It is possible that a peptide hormone called hepcidin (a protein produced in the liver) blocks iron uptake in the gut mucosa (duodenum and ileum) in athletes. Low value of hepcidin enhance the absorption of iron from the gut and therefore normally is low in iron deficiency anemia. However, hepcidin production increases with inflammation, and it is well known that exercise increase inflammation acutely. This may be the cause of that iron-deficiencies are fairly common issues among elite endurance athletes. It may also limit the window in which athletes can take in iron, especially when they train multiple times a day.
Simplistically, the synthesis of hepcidin is controlled by 3 kinds of signals:
When should you consider take a blood test? If you as an endurance athlete are feeling tiered without any obvious reason you should consider taking a test. The challenge is to find a doctor that have the knowledge how to interpret the results.
The greatest portion of iron in humans is in hemoglobin. Except in cases of great blood loss, pregnancy, or growth spurts, where larger amounts of iron are required, our bodies only need about 1 to 1.5 milligrams of iron per day to replace what is lost. Normal daily loss of iron excreted through urine, vaginal fluid, sweat, feces, and tears total about 1-1.5 milligrams, or the equivalent of what most of us require per day to function normally.
The most important blood test to take is :
And what is ferritin?
If iron is the reason for the low hemoglobin (which is most often) then you have Iron Deficiency Anemia. However, if you have a low ferritin, but your hemoglobin is still normal, you only have iron deficiency. The difference is important as anemia is certainly more severe, but research clearly shows that having iron deficiency without anemia can lead to fatigue, lower productivity, and ultimately could lead to reduced endurance (This last situation is why it is so important taking a blood test as an endurance athlete. If you have anemia I think most of us will have symptoms leading to consulting a doctor, but if you only have iron deficiency you may not be aware about it).
Before going further we have to decide which blood tests to take and what are the normale values. The values are different between men and women.
Hemoglobin (Hgb) Male 13,8 – 17,2 g/dL Female 12,1 – 15,1 g/dL
Hematocrit Male 40,7 – 50,3 % Female 36,1 – 44,3 %
Ferritin Male 24 – 336 ng/mL Female 11 – 307 ng/mL
Soluble Transferrin Male 2.2-5.0 mg/L Female 1.9-4.4 mg/L
Iron (serum Fe) 9 – 34 µmol/L
Total Iron binding capacity 49 – 83 µmol/L
If you are a male and have a Hgb < 13 g/dL you have an iron deficiency anemia and likewise if you are a female and have a Hgb < 12 g/dL.
The problem is when you have normal Hgb values and somewhat low ferritin values. In this group there will be people suffering of iron deficiency which can give fatigue and lowering the athletic performance. There is lot of discussion of what are the normal blood test values and when to consider if an athlete should be treated with iron supplement or not. Normal values for one person doesn’t need to be normal for another person! There are individual differences and reactions how athletes tolerate iron loss. That’s why I think it’s important to take at least two blood tests each year to follow up your normal individual values. If there are changes you must discuss that with your doctor and if necessary take the required measurements to solve the issue.
The two most important blood tests are hemoglobin and ferritin. It’s important to know that ferritin can be false negative. If you have an inflammation going on it can show normale value even if you have iron deficiency. I will recommend that you ask your doctor to take a CRP-test. C-reactive protein (CRP) is found in blood plasma, whose levels rise in response to inflammation.
While these tests are somewhat standard the normal limits for the general population are not the same as the normal limits for athletes. I will recommend athletes should have a ferritin above 30 and the lower level of Hgb is 15.7 for males and 14.0 for females.
A doctor and specialist in pathology. He has always been concerned about health and how to manage a good and healthy lifestyle. The blog will mainly be about the use of essential oils, health, and training.