Iron
What is Iron?
Iron is an essential component of proteins involved in oxygen transport.
Food Sources of Iron
Healthy adults absorb about 10% to 15% of dietary iron, but absorption varies depending on the individual and other factors. Storage levels of iron have the greatest influence on iron absorption. Iron absorption increases when body stores are low. When iron stores are high, absorption decreases to help protect against toxic effects of iron overload. Iron absorption is also influenced by the type of dietary iron consumed. Absorption of heme iron from meat proteins is efficient. Absorption of heme iron ranges from 15% to 35%, and is not significantly affected by diet. However, only 2% to 20% of nonheme iron in plant foods is absorbed and is affected by other food components. Meat proteins and vitamin C will increase absorption of nonheme iron whereas tannins (found in tea), calcium, polyphenols, and phytates (found in legumes and whole grains) decrease absorption of nonheme iron (12). |
Why Iron is Important for Female Distance Runners
Adequate iron intake is particularly important for endurance athletes because poor iron status may impair the synthesis of hemoglobin and myoglobin, essential components in the transport and delivery of oxygen to the muscles (21).
Three groups of athletes may be at greatest risk of iron depletion and deficiency: female athletes, distance runners, and vegetarian athletes. It is particularly important for members of these groups to consume recommended amounts of iron and to pay attention to dietary factors that enhance iron absorption. If appropriate nutrition intervention does not promote normal iron status, iron supplementation may be indicated.
Three groups of athletes may be at greatest risk of iron depletion and deficiency: female athletes, distance runners, and vegetarian athletes. It is particularly important for members of these groups to consume recommended amounts of iron and to pay attention to dietary factors that enhance iron absorption. If appropriate nutrition intervention does not promote normal iron status, iron supplementation may be indicated.
Minimum Daily Iron Requirements
The Dietary Reference Intake (DRI) for iron is 8 mg (males; females 51 and above) and 18 mg (females, ages 19 to 50). Iron requirements may be even higher for female athletes, particularly vegetarians or those involved in intense and/or prolonged training (6).
Risks Associated with Consuming Too Much Iron (From Supplements)
Perhaps due to the prevalence of dietary iron inadequacy, iron is the most popular mineral supplement used by athletes (11). It is important for all athletes to understand that there are risks associated with excess iron intake especially in supplemental form. The Tolerable Upper Intake Level (UL) for iron is 45 mg.
|
Signs and Symptoms of Iron Deficiency
One study found that 51% of NCAA Division I female collegiate athletes did not meet the RDI (15 mg/day for 14–18 years and 18 mg/day for 19–30 years) for iron and 4.2% were below the EAR (8 mg/day for 19-30 years) (6).
A deficiency of iron limits oxygen delivery to cells, resulting in fatigue, poor work performance, and decreased immunity. Signs of iron deficiency:
|
|
Watch this video and use this handout to learn about iron related blood tests
To read and download the Iron Handout, Click here
To read and download the Iron Handout, Click here