How Does Low Iron Affect Running?

iron supplements

You should know all the facts about ferritin and iron before you decide to start supplementing. You’ve been training hard for an upcoming race, but lately you’ve struggled to complete exercise. You are sleeping more but still feel tired. Should you get your iron levels checked? Iron is important, but not all that you hear is true.

In this article, you will find answers to most common questions.

What effect does low iron have on running?

Iron, a trace element in the body, impacts the function of the immune system and energy production system, but its most important role is in getting oxygen to your muscles. Iron is the main component of hemoglobin, the transport agent for oxygen and carbon dioxide in the blood. It’s also present in muscles in the form of myoglobin, the protein that extracts oxygen from hemoglobin molecules. For metabolism and transport of oxygen to function properly, a sufficient level of iron has to be available. This is especially true during growth and exercise.

Does running make you more likely to be anemic?

In general, workout doesn’t predispose an athlete to anemia, but the symptoms connected to anemia—most commonly excessive fatigue—may become apparent earlier in an athlete. Anemia is a sign of a deficiency of red blood cells (RBC) in the body. There are various causes, with iron deficiency being the most common. Anemia could also be a result of excessive loss and/or inadequate production of RBC.

iron rich food
Tomatoes belong to iron-rich foods.

Is anemia common among runners?

The prevalence of anemia in U.S. men under the age of 45 years is 0.2-0.6%. Because of a variety of medical conditions, this increases to 1.8% in men aged 75 years and more. The prevalence in women is about 3%. Iron deficiency anemia is more frequent in women of childbearing age, because of menstrual loss, especially together with insufficient intake of iron in the diet. Vegetarians are at increased risk of anemia if they aren’t careful about dietary intake.

There’s not an increased prevalence of anemia in athletes, but mild anemia that might go unnoticed in the general population can affect athletic performance. While anemia may not be more common in athletes, research has discovered that ferritin levels may be lower in female athletes and in male endurance athletes than in their non-athletic counterparts. If iron stores are low and there’s greater loss of RBCs than production, this may progress to anemia. If iron stores are lower than 20ng/ml (some will even say 30ng/ml), iron supplementation would be recommended.

One result of regular endurance exercise is that it produces an increase inred blood cell mass and plasma volume. This results in a better delivery of oxygen to exercising muscles and more effective elimination of carbon dioxide. The increase in plasma volume due to exercise is greater than the increase in RBC mass, leading to a slightly lower hemoglobin level in runners than in non-athletes.

This dilution is known as athletic pseudoanemia and isn’t a real anemia. If a runner is tested low but not having symptoms, no change is necessary. The runners experiencing unexplained fatigue or decrease in performance should take a few days off from training. If anemia caused the symptoms, the hematocrit and hemoglobin wouldn’t improve; if results were a result of dilution, the numbers would normalize, indicating that anemia wasn’t causing the problems.

anemia
Anemia is a sign of a deficiency of red blood cells (RBC) in the body. There are various causes, with iron deficiency being the most common.

How is ferritin different from iron, and is it important for runners?

Iron is stored as ferritin in the liver, spleen and bone marrow. Ferritin levels measure these iron stores in the body; levels lower than 12ng/ml are connected to a lack of bone marrow iron stores. The level of ferritin has a significant impact on the absorption of iron from the foods you eat. Absorption is enhanced when stores are low. The actual level that’s considered low varies in different studies.

Low levels of ferritin don’t necessarily imply that someone is anemic. There’s disagreement as to whether low ferritin levels have an effect on athletic performance. In several studies, low levels didn’t affect VO2 max. Other studies showed improvement in performance after athletes who had low ferritin levels, but not anemia, supplemented their iron intake. This may be because of a relative anemia (hemoglobin is in the normal range, but is low for the particular athlete) and not just a low ferritin level. The athletes (all women) who experienced improvement in performance had hemoglobin levels at the lowest end of the normal range; they experienced an increase in hemoglobin level in addition to improved performance. Fot other athletes with comparable initial blood tests nothing changed in hemoglobin level after taking iron supplements.

If your hemoglobin or hematocrit (percentage of RBC) level is at the low end of the optimal range, a trial of iron supplementation might produce an increase in these levels and a related performance improvement.

running
Foot-strike hemolysis was first thought to be a result of compression of capillaries in the feet while running, but this is not the case.

Does the pounding of running cause red blood cell loss or iron loss?

There’s a phenomenon referred to as foot-strike hemolysis (more appropriately called exertional hemolysis) in which red blood cells are destroyed during workout. This was first thought to be a result of compression of capillaries in the feet while running or marching, but additional factors have to be considered, because this process has also been found in rowers, swimmers and weightlifters. The blood cell loss usually isn’t significant enough to be detected on a routine blood test. We all lose iron every day. Small amounts are lost through the gastrointestinal tract, and trace amounts are lost in sweat and in urine.

How much iron do you need? Do you need it more as a runner?

The recommended daily intake for elemental iron varies in dependence of gender and age, ranging from 8mg/day to 18mg/day (27mg/day during pregnancy). The higher range of intake could be difficult to maintain, particularly for vegetarians, who need to take in more iron because less is absorbed from non-meat sources.

Heme iron, found in red meat and dark poultry, is a more readily available source of iron (18% absorbed). Our bodies absorb about 10% of non-heme iron from grains and vegetables. Vitamin C, taken along with a meal, enhances the absorption of non-heme iron, as does meat protein. Tannins (present in tea) and calcium can reduce absorption.

iron supplements
Iron supplementation in a low dose isn’t dangerous for most individuals.

Should you supplement iron?

Iron alone doesn’t improve the production of RBCs; this is a complex process that involves several elements that have an effect on the bone marrow. When cells are depleted of iron, supplementation will increase the hematocrit and hemoglobin. If levels aren’t low, additional iron won’t produce more RBCs, nor provide improvement in performance.

Iron supplementation in a low dose isn’t dangerous for most individuals, but it’s possible to develop an iron overload. About 1 person in 250 of Northern European descent carries the gene for hemochromatosis, a disorder in which iron is absorbed too efficiently and excess amounts are deposited in the body organs. Only around 10% of those with the abnormal gene develop considerable organ damage.

Hemochromatosis is usually not diagnosed until damage to organs has already occurred (heart failure, cirrhosis). Iron supplementation, even the amount in a multivitamin, may speed up the effects of this disorder. Supplements can also mask underlying medical conditions, such as celiac disease and occult blood loss from the GI tract, which will delay the diagnosis and appropriate treatment of these problems.

The effect of iron supplementation on the performance of athletes with low ferritin levels without anemiaremains unclear. Research continues on this subject, and at some point, the data may provide more definitive answers. Due to the importance of iron in the body, supplementing low levels of ferritin to avoid depletion of iron stores is recommended. The amount of iron in a multivitamin can supplement dietary intake and is secure within the absence of an iron storage illness, resembling hemochromatosis. This small quantity won’t trigger a change in the complete blood count (CBC) or ferritin level. Greater doses are needed to impact the ferritin level. You need to discuss the appropriate dose of iron supplementation with your health care provider.

As the dose of the supplement increases, so does the possibility of gastrointestinal side effects, including nausea, vomiting, constipation and abdominal discomfort.

iron-rich food
Opt for iron-rich foods.

When should you get checked?

If you’re healthy and your training is going well, you don’t need to be screened for anemia or low iron stores. Even though it would be nice to see the results, your insurance company may not pay for blood tests for asymptomatic screening. Women with heavy menstrual bleeding and vegetarians are at greater risk of low iron stores and anemia, and screening may be justified. If you have a history of a medical problem that could cause anemia (such as an ulcer or celiac disease), blood tests may be warranted.

If you’re experiencing unexplained fatigue and/or a decrement in performance that has persisted for several weeks, a CBC and ferritin level are good first screening tests for anemia. If anemia isn’t detected and iron stores are low, you could work on improving your diet and/or take an iron supplement. Discuss this with your health care provider to make sure that there’s no contraindication. If anemia is detected, it’s crucial to find out the cause of this problem in as well as start iron supplementation. You must avoid iron supplementation if you have a family history of hemochromatosis. Your health care provider should test you for this disorder.

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Written by Camille Bennett

Camille Bennett is our nutrition expert interested in fitness diet and doesn’t run out of delicious ideas for healthy and nutritional meals.

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