Effect of meals with milk on body iron stores and improvement of dietary habit during weight loss in female rhythmic gymnasts

Abstract

This study investigated the effect of different timings of milk intake on body iron stores and improvement in the dietary habit of female collegiate rhythmic gymnasts. Subjects took iron tablets at both breakfast and dinner times during a weight-loss period. In addition, subjects ingested low-fat milk twice a day either at breakfast or dinner (group I; n=7), or between meals (group II; n=6) for 3 mo. Blood was collected four times. Red blood cell count, hemoglobin, serum iron, ferritin and erythropoietin concentrations were measured. Subjects completed a dietary survey for three consecutive days before each blood sampling. The mean body fat in both groups I and II was significantly lower after 3 mo than at the start of the study (p<0.01). Red blood cell count and hemoglobin of group I were significantly higher as compared to those of group II (p<0.05). Serum iron concentrations and transferrin saturation values remained unchanged in both groups. Serum ferritin concentrations in group I were significantly higher 3 mo after the start of the study, but this was not observed in group II. Energy and carbohydrate intake in group II, but not in group I, were significantly lower after 3 mo as compared to those after 1 and 2 mo as a result of missing meals. In conclusion, iron-supplemented meals via milk ingestion did not decrease body iron stores and maintained higher body iron stores compared to a diet that included milk intake between meals. Further, milk intake with meals is related to keeping regular meal times and frequency.