This cross-sectional study explored the prevalence of iron deficiency (ID) and associations between dietary factors and incidence of ID in female rhythmic gymnasts during preseason periods. Participants were 60 elite collegiate rhythmic gymnasts (18.1 ± 0.3 years [M ± SD]) who were recruited every August over the course of 8 years. Participants were divided into 2 groups according to the presence or absence of ID. Presence of ID was defined either by ferritin less than 12 µg/L or percentage of transferrin saturation less than 16%. Anthropometric and hematologic data, as well as dietary intake, which was estimated via a semiquantitative food frequency questionnaire, were compared. ID was noted in 48.3% of participants. No significant group-dependent differences were observed in physical characteristics, red blood cell counts, hemoglobin, hematocrit, haptoglobin, or erythropoietin concentrations. The ID group had a significantly lower total iron-binding capacity; serum-free iron; percentage of transferrin saturation; ferritin; and intake of protein, fat, zinc, vitamin B2, vitamin B6, beans, and eggs but not iron or vitamin C. The recommended dietary allowance for intake of protein, iron, zinc, and various vitamins was not met by 30%, 90%, 70%, and 22%–87% of all participants, respectively. Multiple logistic analysis showed that protein intake was significantly associated with the incidence of ID (odds ratio = 0.814, 95% confidence interval [0.669, 0.990], p = .039). Participants in the preseason’s weight-loss periods showed a tendency toward insufficient nutrient intake and were at a high risk for ID, particularly because of lower protein intake.
Kokubo is with the Department of Food and Nutritional Environment, College of Human Life and Environment, Kinjo Gakuin University, Aichi, Japan. Yokoyama and Sunami are with the Graduate School of Agriculture, Tokyo University of Agriculture, Tokyo, Japan, and the Japan Society for the Promotion of Science, Tokyo, Japan. Kisara and Ishizaki are with the Department of Sport Wellness Science, Faculty of Sport and Health Sciences, Japan Women’s College of Physical Education, Tokyo, Japan. Ohira is with the Fujisangyo Co., Ltd, Chiba, Japan. Yoshizaki is with the Faculty of Food and Nutritional Sciences, Toyo University, Gunma, Japan. Tada, Hida, and Kawano are with the Department of Food and Nutritional Science, Faculty of Applied Bio-Science, Tokyo University of Agriculture, Tokyo, Japan.