Iron Supplementation for Athletes and Long-Distance Runners

Isabel del Barrio 5 min. of reading Minerals Leave a comment

Iron is one of the most important minerals for sports performance, especially in endurance disciplines such as running, trail running, cycling and triathlon. Despite its importance, iron deficiency and sports anemia are among the most common nutritional deficiencies in athletes, directly affecting their performance, recovery and health.

If you notice unusual fatigue, an increase in your heart rate when running at an easy pace, or feel that your legs just “won’t respond”, your ferritin levels might be trying to tell you something.

Why is iron essential for performance?

Iron is a central component of hemoglobin (the protein in red blood cells responsible for transporting oxygen from the lungs to the muscles) and myoglobin (which stores oxygen within the muscles for use during contraction).

In long-distance runners, oxygen demand is extremely high. If your iron stores (ferritin) are low, your blood’s ability to transport oxygen may be compromised. The result? VO2 max (maximum oxygen uptake) can decrease, energy metabolism becomes less efficient and chronic fatigue may develop.

Causes of iron deficiency in runners (Sports anemia)

Endurance athletes lose more iron than sedentary individuals. The main causes of this mineral loss include:

Foot-strike hemolysis: with every stride, the repeated impact of the foot against the ground can destroy a small number of red blood cells. During long runs or marathons, this continuous breakdown may contribute to iron loss.
Sweat losses: small amounts of minerals, including iron, are excreted through sweat.
Gastrointestinal microbleeding: extreme physical stress and reduced blood flow to the digestive system during intense exercise can cause small, often unnoticed gastrointestinal bleeds.
Menstruation in female athletes: female runners face an additional risk factor due to the combination of exercise-related iron losses and monthly menstrual blood loss.

Sports pseudoanemia (Dilutional anemia)

Not every decrease in hemoglobin levels in a blood test is a cause for concern. During endurance training, the body increases blood plasma volume (the liquid component of blood) as a physiological adaptation. This “dilutes” the red blood cells, making hemoglobin concentrations appear lower in blood tests. This is why it is essential for a sports medicine specialist to assess not only serum iron, but also ferritin and transferrin levels.

Symptoms of iron deficiency in athletes

If you have an iron deficiency, your body may show noticeable warning signs during training:

Unexplained increases in resting and exercise heart rate.
Difficulty maintaining your usual interval training pace.
Chronic muscle fatigue and a feeling of heaviness or “heavy legs”.
Much slower recovery between training sessions.
Paleness, weakness and irritability.

HSN iron supplements and selected formulas

One of the biggest concerns runners have when buying iron supplements is gastrointestinal discomfort. Many conventional iron supplements available in pharmacies (such as ferrous sulfate) can cause stomach pain, heaviness or constipation, which can interfere with training.

At HSN, we have developed highly bioavailable iron supplements designed to be gentle on your stomach, making them suitable for periods of intensive training:

Iron Bisglycinate 20mg and Ferrochel® (30mg): because the iron is chelated with glycine, it remains stable in the acidic environment of the stomach and is absorbed in the intestine. This form is known for its excellent gastrointestinal tolerance and reduced risk of digestive discomfort.
Liposomal Iron (30mg): LipoCellTech™ technology encapsulates iron within a liposomal structure, designed to improve its bioavailability while reducing direct contact between the mineral and the digestive tract.
Hemo Care: if you are looking for comprehensive nutritional support for normal hemoglobin formation, this formula combines iron with key cofactors such as Vitamin B12, B9 and Vitamin C.

How and when should runners take iron?

To maximize iron supplement absorption and restore your ferritin levels ahead of your next competition, follow these recommendations:

Combine it with vitamin C: a glass of orange juice, a kiwi or a Vitamin C supplement can help improve iron absorption.
Take it on an empty stomach or between meals: ideally, take it 30 to 60 minutes before breakfast, provided it is well tolerated.
Avoid absorption inhibitors: do not take iron supplements alongside coffee, tea, dairy products (calcium), or magnesium and zinc supplements.
Separate it from training: intense exercise increases levels of a hormone called hepcidin, which reduces iron absorption. It is generally preferable to take your supplement several hours before running, or in the morning if you train in the afternoon.

Sources

A., Garvican, L., Lobigs, L., Telford, R., Fallon, K., J., Gore, C. Haemoglobin Mass in an Anaemic Female Endurance Runner Before and After Iron Supplementation. International Journal of Sports Physiology and Performance, 2011, 6, 137-140 © 2011 Human Kinetics.
Chatard, J-C., Mujika, I., Guy, C., Lacour, J-R. Anaemia and Iron Deficiency in Athletes. Sports Med 1999 Apr; 27 (4): 229-240
Coates, A., Mountjoy, M., Burr, J. Incidence of Iron Deficiency and Iron Deficient Anemia in Elite Runners and Triathletes. Clin Journal Sport Med.
Clénin, G., E., Cordes, M., Huber, A., Schumacher, Y., O. Noack, P., Scales, J., Kriemler, S. Iron Deficiency in sports – definition, influence on performance and therapy. Swiss Sports & Exercise Medicine, 64 (1), 6–18, (2016).
Alaunyte, L., Stojceska, V., Plunkett, Andrew. Iron and the female athlete: a review of dietary treatment methods for improving iron status and exercise performance. J Int Soc Sports Nutr. 2015; 12: 38. (2015).
Zourdos, M., C., Sanchez-Gonzalez, M., A., Mahoney, S. A Brief Review: The Implications of Iron Supplementation for Marathon Runners on Health and Performance. The Journal of Strength and Conditioning Research 29(2) · July 2014

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