Dietary and biochemical indices of nutritional status in male athletes and controls

Abstract

To determine whether physical exercise affects biochemical indices of nutritional status, we compared four groups of male athletes (total n = 427) with two control groups (n = 150). Data about their nutrient intake for 1 month were obtained from a 122-item food frequency questionnaire. An estimate for leisure energy expenditure (EE) was calculated from a 15-item physical activity questionnaire. Athletes were grouped according to their EE (ModEE and HighEE athletes) and weight (light = less than 75 kg; heavy = greater than or equal to 75 kg), and controls according to their weight. Mean energy intake in ModEE and HighEE athletes was 2805-3260 kcal/day. Leisure EE significantly (p less than 0.0001) affected energy and nutrient intakes. Energy, riboflavin and calcium intakes were also higher in heavy subjects (P = 0.0006-0.03). The estimated percentage of subjects with deficient dietary intakes, calculated from probability analyses, was 0-6, depending on group and nutrient. Erythrocyte transketolase activation coefficient (E-TKAC) was highest in controls (1.17 +/- 0.0008; p = 0.001). Serum magnesium was highest (p = 0.01) in ModEE athletes (0.85 +/- 0.006 mmol/L). No intergroup differences were found for plasma ascorbic acid, serum zinc or serum ferritin concentration, whereas blood hemoglobin was lowest (p less than 0.001) in HighEE athletes (149 +/- 0.5 g/L). Ten percent of the control subjects had E-TKAC greater than 1.24. Percentage of other values outside reference range was 0-4, depending on group and indicator. Since lowered blood hemoglobin concentration can be explained by hemodilution, we conclude that sports training did not have a negative effect on biochemical indices of thiamin, vitamin C, magnesium, iron, or zinc status in Finnish male athletes.