Iron for cyclists

While altitude training and racing are on our minds at this time of the year, it's a good time to discuss iron, as this important mineral is essential for oxygen transport. 

Iron is a key component of hemoglobin and supports energy metabolism, mitochondrial health, and endurance capacity. Even if you have not been classified as anemic based on blood work, being low in iron without changes in hemoglobin can still result in measurable declines in VO₂max, performance, and recovery. 

Endurance athletes can often be at higher risk for low iron due to a combination of factors, including iron losses via sweating and bleeding (including in GI), inflammation and action of the hormone hepcidin (which is increased following training), menstruation in female athletes, low energy availability, and dietary restrictions that result in low to no intake of heme-based iron. While female athletes are particularly at risk for iron deficiency, especially during periods of high training load, males can also be at risk and should be screened when symptoms develop or prior to targeted periods of altitude training. 

Possible symptoms of low iron

Recognizing iron deficiency can be a challenge, as the symptoms are very similar to those seen with general training fatigue, but if any of the following seem to be consistently present, it makes sense to evaluate your iron status.

• Reduced power or pace with normal heart rate

• Persistent fatigue, especially early in rides

• Heavy legs or poor recovery between sessions

• Mood swings, poor sleep, brain fog, or decreased focus

Diagnosing low iron

The only way to know for sure is with an iron panel blood test that you may need to specifically request from your healthcare provider. This test includes measuring hemoglobin and hematocrit, as well as ferritin, which is reflective of iron stores and the most common biomarker of iron status.

Based on current recommendations:

• Ferritin <30 ng/mL = iron deficiency

• Ferritin <50 ng/mL = iron insufficiency that may be suboptimal for endurance performance

• Ferritin <100 ng/mL = may impair performance in elite or high-volume athletes

Should you supplement?

An average diet might include 10-15 mg of iron daily, but only a very small amount of this is actually absorbed in the body. Animal-based food sources like red meat, liver, chicken, and fish contain heme iron, which is better absorbed in the body, but beans, lentils, tofu, quinoa, and leafy greens contain non-heme iron, as well. Including vitamin C foods such as bell peppers, citrus fruits, and strawberries can help absorption. As a bonus, use a cast iron skillet for cooking. 

Supplementation should only be considered if warranted by iron insufficiency or deficiency confirmed by a blood test, as iron can become toxic if overloaded. When iron is low, a common dose of 45-65 mg elemental iron is prescribed daily or using alternate day dosing.

Additional strategies for improving the response to supplementation include:

• Supplementing within 30 minutes post- morning workout 

• Take supplement with vitamin C

• Avoid caffeine, magnesium, calcium, zinc and high fiber foods around time of iron supplementation

  
  

Iron and altitude training

Athletes will often undertake some type of altitude training protocol with the purpose of driving hematological adaptations such as increased hemoglobin mass. However, because adequate iron status ahead of altitude training is important for attaining the adaptations, athletes are often recommended to increase ferritin values to >50 ng/mL. Check your iron status six to eight weeks prior to altitude training and supplement as recommended by a sports dietitian or physician.

Additional factors

Iron status is one of the things the body is very good at regulating so it doesn't reach dangerous levels. Hepcidin is important in this homeostatic regulation, so anything that influences hepcidin (e.g., training, energy intake and carbohydrate intake) is something to consider when trying to alter the body's iron status. Adequate levels of Vitamin D and B12 may also contribute, suggesting that simply taking a daily iron supplement may only be part of an athlete's strategy to achieve optimal iron.

PMID: 28453305, 39536912, 38407751, 37895389, 40248655

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At BaseCamp, we believe that every cyclist has the potential to achieve greatness, no matter where they start. Our mission is to create a community-driven training environment where cyclists and triathletes of all levels can train together, support each other, and grow stronger, faster, and more confident in their abilities. Our cycling training programs are expert driven and tailored to your needs. Whether you're a seasoned pro or just getting started, BaseCamp is where you belong.