Dietary intake and iron deficiency in middle age female distance runners
The role of food intake and nutrition in athletic performance has gained much recognition in recent years. Therefore, the purpose of the present investigation was to assess whether female runners who consumed a modified vegetarian diet had different iron parameters than female runners who consumed a diet that included red meat. Methods: Two groups of female runners (n=18) volunteered as subjects for this study. One group was composed of women who regularly consumed a modified vegetarian diet (V group) and the other group was composed of women who consumed a diet which included red meat (RM group). The groups were comparable in age, weight, aerobic capacity, number of pregnancies and years since last pregnancy. Dietary analyses and biochemical analyses for the three stages of iron deficiency characterized by iron depletion, iron deficient erythropoiesis and iron deficiency anemia were performed to compare iron status of the two groups of athletes. Results: Serum ferritin values of the V group were significantly lower (p=.001) than those of the RM group. Of all the athletes examined, 56% had serum ferritin values indicative of storage iron depletion. Mean values for serum iron, total iron binding capacity (TIBC) and percent transferrin saturation were in the normal range for both groups, but TIBC values of the V group were significantly higher (p=.02) than the TIBC values of the RM group. Individually, four of the subjects, 22%, (3 V group and 1 RM group), had iron values indicative of iron deficient erythropoiesis. None of the other iron parameters was significantly different between the groups and none of the subjects was clinically anemic. The mean daily iron intake was not significantly different between the groups, but both groups averaged less than the RDA. The total caloric intake of both groups averaged less than 1800 kcals/day with 50% of the athletes consuming less than 1800 kcals/day, and another 28% consumed between 1800-2100 kcals/day. The V group consumed significantly more carbohydrate (p=.02) and less protein (p=.001) than the RM group, but none of the other dietary variables were significantly different between the groups. Conclusion: The two groups of subjects ingested almost the same amount of iron/day, however, the bioavailability of the iron in the diets may have affected iron absorption as the iron stores of the V group were lower than those of the RM group.