Thursday, October 6, 2011

Nutrition - Iron Deficiency


 IRON DEFICIENCY
  
     As strong as today’s female athletes are, it is not unusual for them to develop iron deficiencies.  Studies are showing higher rates of depletion among athletes, especially female athletes, compared to sedentary populations.  Even with knowledge, the performance effects and causes of anemia still remain unclear.

     Iron plays a number of important roles in the body, including oxygen transportation, metabolism and immune function.  Despite wide spread use of iron-fortified foods and iron supplements; iron deficiency remains one of the most common nutritional deficiencies.

     The term “iron deficiency” can be confusing because it is used to describe a range of conditions related to iron status.  In scientifically correct terms, full-blown iron deficiency anemia, which takes a long time to develop, progresses in three stages:  (1) Iron Depletion; (2) Iron Deficiency; and (3) Iron-Deficiency Anemia.

     Stage one, iron depletion, is signified by a serum ferritin level below 12ug/l.  Athletes can often function with no problems at this early stage.  In the most advanced stage – iron deficiency anemia, symptoms may include fatigue, weakness, pallor, breathing difficulty, heart palpations, and poor body temperature regulation.  While the first and last stages are clearly defined, stage two is more difficult to diagnose.

     From a practical standpoint, it isn’t really necessary to pinpoint the stage of iron depletion / deficiency, but rather to monitor athletes with depleted stores.  Most physicians will test athletes annually at their physical and flag anyone with levels below 12ug/l.  The signs and symptoms of anemia should be reviewed with the parent and athlete to see if there is any evidence of anemia.  If there are symptoms of anemia, further blood testing may be indicated and dietary measures to boost iron stores are initiated.

     Full-blown iron-deficiency anemia is relatively rare among athletes and the general population.  However, the prevalence of iron depletion and iron deficiency is much higher.  Population groups that are at higher risk of developing iron deficiencies include women, children, adolescents, and athletes.  During any period of growth, such as the adolescent growth spurt, the demand for iron is high due to increased blood volume and lean muscle.  Menstruating women lose approximately 0.6 mg of iron per day on average, with loses of 0.9 mg/day occurring in 25 percent of women.  Among endurance athletes, iron depletion is reported to be as high as 82 percent.

    




     The most common cause of iron deficiency is related to inadequate dietary intake.  Iron is NOT very abundant in the diet – every 1,000 calories contain an average of 6mg of iron.  Women who are on calorie restricted diets frequently fail to meet their requirement of 15mg/day.  Since men have higher caloric needs and a lower iron requirement (10mg/day), it is easier for them to avoid iron deficiencies.  Athletes who participate in weight-restricted sports such as wrestling, gymnastics, and dance may not consume enough iron.

     The emphasis on a high-carbohydrate, low-fat diet for athletes can also contribute to low iron intake.  Red meat, a food avoided by many athletes who strive for a low-fat diet, is one of the richest sources of iron.  Non-meat, high carbohydrate foods, on the other hand, tends to be lower in iron content.

    
Food Sources of Iron
Food                                                                                   Iron Content (mg)
Animal Sources
Liver, chicken (3 oz.)                                                                   8
Liver, beef (3 oz.)                                                                        7
Pork Chop (3 oz.)                                                                        4
Beef (3 oz.)                                                                                  3.5
Chicken, dark meat (3 oz.)                                                          1

Vegetable Sources
Cereal, ready-to-eat, fortified (1 oz.)                                           4.5
Lentils, cooked (1/2 cup)                                                             3.5
Spinach, cooked (1/2 cup)                                                           2
Raisins, (2/3 cup)                                                                        2
Apricots, dried (10 halves)                                                          1.5
Rice, enriched, cooked (1/2 cup)                                                 1.8
Bagel (1)                                                                                      1.5

     Dietary factors appear to play a much larger role than exercise factors when it comes to iron deficiencies.  The most frequently cited cause of exercise-induced anemia is foot strike hemolysis, which is the destruction of red blood cells from the impact of the feet striking the ground during running.  However, the body has a mechanism to recycle the iron when red blood cells are destroyed in this manner.

     What is the recommended treatment for iron deficiency?  Most physicians recommend using iron supplementation as a last resort, only after a period of monitoring and dietary intervention to increase food sources of iron.  There are a number of risks associated with iron supplementation.  In addition to the risk of toxicity, iron is associated with increased free-radical production.  If supplements are taken they should be combined with other foods to enhance iron absorption.  For example, vitamin C enhances iron absorption; therefore drink orange juice, not coffee with an iron pill.

     Iron supplementation will have no performance enhancing effect for athletes with normal iron status and results are inconclusive on whether athletes with depleted iron stores benefit in performance.  We do know that iron supplementation alone for anemia is not beneficial; it must be combined with healthy eating.  First and foremost, the athlete should be monitored and advised on healthy food choices to maintain iron stores throughout their life time.

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