Iron is an important micronutrient in pathways of energy production. Quite simply, iron is essential for the transport of oxygen in red blood cells and the uptake of oxygen by muscle cells to produce energy for running. Since efficient oxygen delivery is the most important predictor of success in an aerobic event like 5000m cross country racing, iron is a big deal. Multiple studies have shown that athletes with low iron stores, even in the absence of anemia (low red blood cell counts or low hemoglobin levels), have declines in athletic performance.
Iron deficiency is common among endurance athletes, particularly young women athletes for whom the prevalence may be as high as 2/3 of all high-school and college age runners. Up to 1/3 of young men runners are iron deplete. Girls are at higher risk than boys for low iron stores due to obligatory blood loss through menstruation. Athletes who restrict their intake of red meat are also at higher risk of low iron stores because iron from other dietary sources is not as easily absorbed.
Ferritin is a protein measured by a simple blood test and gives the best estimate of a person’s total iron stores. Of Denver East athletes who have had their ferritin levels checked in the last eight years, nearly 100% of our girls and more than 50% of our boys have had low levels of ferritin. Clearly there may be some selection bias, since we have generally asked our athletes who had more overt symptoms to be tested, but the point is the same: iron deficiency is very common. Over the last couple years our recommendation for ferritin testing has evolved from recommending it only for those athletes who had symptoms to recommending that all our athletes have ferritin checked at least once per year. We are not alone: the best high school programs around the country are encouraging their athletes to have their ferritin levels checked and the collegiate programs to which we have sent East graduates are monitoring their athletes’ ferritin levels every 3-6 months.
Our athletes who have had low ferritin levels experienced plateaus in their racing performance despite consistent training, general fatigue, and difficulty recovering from workouts and races. Our athletes who have successfully repleted low iron stores have reported generally just feeling “better,” in addition to seeing improvements in their running performances.
There is some controversy as to what is a “normal” ferritin level. While levels as low as 15ug/L are not always associated with significant anemia, most exercise physiologists recommend a level of at least 35ug/L, and a few studies suggest a benefit to reaching a level of at least 50ug/L.
Supplementing with oral iron to bring ferritin levels to normal presents some challenges. Iron is not easily absorbed, and it takes 6-8 weeks to replete low iron levels. Multiple studies have shown that iron bisglycinate (rather than ferrous sulfate or ferrous fumarate) has superior absorption and tolerability, though it can be a bit more expensive and harder to find in pharmacies (it is easily found online). We recommend taking iron supplements along with vitamin C (which aids in absorption) at bedtime. For those who supplement with a multivitamin or calcium, we recommend taking those in the morning since calcium interferes with iron absorption. 25-50mg of elemental iron per day is a safe supplemental dose for teen female athletes and those teen male athletes who restrict their intake of red meat. Athletes whose ferritin levels are low may need to supplement with up to double those doses.
The bottom line: We recommend ferritin testing for all our athletes and iron supplementation for many of out athletes. Ferritin testing may be covered by insurance when ordered as screening for iron deficiency in at risk individuals – which we believe includes all our female athletes and many of our male athletes. Feel free to ask the coaches about ferritin testing and iron supplementation.
Denver East High XC 