When it comes to the negative outcomes of relative energy deficiency in sport (RED-S), the most well-known outcomes are poor bone health, irregular periods in females, and low testosterone in males. However, new research suggests that under-fuelling may also increase the risk of iron deficiency. As a reminder, RED-S is caused when not enough calories are consumed by an athlete. For more on that click here.

Iron deficiency or iron deficiency anemia occurs when not enough iron is consumed. Athletes have an increased risk of becoming iron deficient because exercise increases iron losses. Iron deficiency is characterized by low ferritin (typically defined as <35 μg/L). Iron deficiency anemia occurs when ferritin levels have become so depleted that hemoglobin is also low. Both iron deficiency and iron deficiency anemia can have detrimental effects on performance.

Under-fuelling can increase the risk of becoming iron deficient because if not enough calories are consumed, it may be difficult to get enough iron through the diet. However, new research suggests that the hormonal response that occurs from under-fuelling can also increase the risk of iron deficiency. Under-fuelling increases the level of a hormone called hepcidin. Hepcidin is the body’s master iron regulator and decreases iron absorption. As a result, even if adequate levels of iron are consumed, if there are high levels of hepcidin, the body may not absorb enough iron. This in turn can lead to iron deficiency.

If an athlete has iron deficiency and is under-fuelling, then increasing caloric intake is critical to help reduce hepcidin levels. However, an iron supplement is also needed since it is very difficult to increase iron levels through food alone. In this situation, an alternate-day single dose of 40-80 mg of elemental iron can be as equally effective as taking an iron supplement every day, while also reducing gastrointestinal side effects. Hepcidin levels also increase 3-6 hours post exercise and naturally throughout the day. As a result, to help increase iron absorption, athletes should take iron supplements in the morning. If exercising in the morning, an athlete should take their iron supplement within 60 minutes of completing exercise. Finally, iron supplements should also be taken away from the consumption of polyphenolic-containing beverages such as tea and coffee that also decrease iron absorption.

More than just bones and reproductive health are compromised due to under-fuelling. Research is just starting to uncover all the deleterious outcomes.  Under-fuelling is a serious concern for all athletes due to the negative impacts on health and performance.

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Categories: Megan Kuikman

Megan Kuikman

Hello! I’m Megan Kuikman. I’m a Registered Dietitian with specialized training in sports nutrition. My goal is to help athletes and active individuals achieve a healthy attitude towards health, training, and food. I empower athletes to fuel properly for training in order to restore their health and enhance performance. You can get in touch with me at: hello@megankuikmanRD.ca


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