The effect of exercise on the riboflavin status of adult men

Abstract

Six sedentary to moderately active men with biochemical signs of riboflavin deficiency were studied under metabolic ward conditions to examine the effects of physical activity on riboflavin status. All participants were subjected to additional exercise (EXER) for an 18 d period between two maintenance (M1 and M2) periods (16 and 13 d respectively) of habitual physical activity. Energy balance and riboflavin intake were maintained throughout the study. Riboflavin status, as judged by a significant reduction in erythrocyte glutathione reductase (EC 1.6.4.2) activation coefficient (EGR-AC), improved on changing from home (1.53 (SD 0.14)) to period M1 (1.36 (SD 0.21)) diets. The exercise period, however, resulted in a significant deterioration in riboflavin status (1.57 (SD 0.31)) which persisted in the subsequent period M2 (154 (SD 0.15)). There was a concomitant fall in the urinary excretion of riboflavin only in the EXER period, when results were expressed as a percentage of the dietary intake of riboflavin. These results suggest an increased demand for the vitamin for selective biochemical functions during exercise. However, the energy cost of walking (treadmill 4 km/h), 50 W and 100 W work-loads (bicycle ergometer) as well as delta mechanical efficiency (DME) did not change during the three metabolic periods. The urinary excretion of riboflavin was inversely related to DME (P -0.49; P < 0.05) and directly correlated with haemoglobin levels (u 0.63; P < 0.005). The present study suggests that riboflavin status further deteriorates during a short period of increased physical activity in individuals whose riboflavin status is marginal.Riboflavin : Glutathione reductase: Physical activity: Mechanical efficiency . ___Studies confined to clinical cases of malnutrition fail to assess the situation in its entirety since they only address the proverbial tip of the iceberg. Investigations on subclinical or biochemical malnutrition, which are major problems in India, are important to rule out any functional consequences on the health and productivity of the population. In India riboflavin deficiency is very common (National Nutrition Monitoring Bureau, 1980), being possibly modulated by dietary as well as non-dietary factors (infection, physical activity etc.; Belko e t Bamji et al. 1987). The basis of the present study was the observed seasonal variations in the riboflavin status of rural Indian women, as assessed by erythrocyte glutathione reductase (NADPH glutathione oxidoreductase; EC 1 . 6 . 4 . 2 ; EGR) activation coefficients (EGR-AC) (National Institute of Nutrition, 1988). Although a majority of women had marked biochemical riboflavin deficiency throughout the year, there was a significant deterioration in riboflavin status during the monsoon season compared with the summer or winter seasons. This change could not be attributed to changes in diet or morbidity. Since during the rains there was augmented physical activity * Present address:

Micronutrients: interaction between physical activity, intakes and requirements

“…Two subsequent studies by the same group 70,71 seemed to support the finding. In a more recent study, Soares et al 72 examined riboflavin status in male subjects with initially marginal E-GRAC results. Because of worsened indicators of riboflavin status during an 18-day exercise-period, the authors suggested increased riboflavin needs because of increased physical activity.…”

Effect of yoga practices on micronutrient absorption in urban residential school children

“…In the present study, Zinc, Iron, Copper and Magnesium showed significant improvement after twelve weeks of yoga practices in experimental group while wait-list control group did not show any significant improvement. Earlier studies also reported that physical activity and yoga have led to improvement in micronutrient absorption24,25,26 ) . Improvement in Zinc, Iron, Copper, and Magnesium in experimental group can be attributed to twelve weeks of yoga training.…”

Impact of women's work on maternal and child nutrition

“…Due to practical constraints, including some mothers' unwillingness to allow blood sampling, biochemical investigations could not be done on all the mothers and children. Biochemical assessment of riboflavin status was included, since it is influenced by physical work (Belko et al, 1985;Soares et al, 1993). Haemoglobin was estimated by the cyanmethemoglobin method and riboflavin status by the erythrocyte glutathione reductase activation test (EGR-AC) (Bamji, 1981;Bayoumi and Rosalki, 1976).…”