RIBOFLAVIN REQUIREMENT OF HEALTHY ELDERLY HUMANS AND ITS RELATIONSHIPTO MACRONUTRIENT COMPOSITION OF THE DIET

The riboflavin requirements of two groups Of riboflavin-deficient, but otherwise healthy, Guatemalan elderly persons over the age of 60 y we re studied by varying the fat:carbohydrate ratio in two diets. The fir st group consumed a diet similar in macronutrient content to a Western -type diet with low carbohydrate and high fat; the second group consum ed a typical Guatemalan diet with high carbohydrate and low fat. Energ y and protein intakes of both groups were similar. Riboflavin status w as monitored by weekly measurements of erythrocyte glutathione reducta se activity coefficient (EGRAC) and urinary riboflavin excretion. Incr easing increments of riboflavin were added to the subjects' diets unti l their status was normalized, as indicated by EGRAC of <1.34 and a sh arp increase in urinary riboflavin excretion. Using the EGRAC method, the mean value of riboflavin intake at which the subjects' EGRAC reach ed the limit of normality was 1.37 +/- 0.03 mg/d in the first phase an d 1.29 +/- 0.03 mg/d in the second phase. The sharp increase in urinar y excretion occurred at riboflavin intakes of 1.13 and 1.03 mg/d for G roups 1 and 2, respectively. Thus, the differences between the two gro ups suggest that diets with a lower fat: carbohydrate ratio can decrea se the dietary need for riboflavin. The dietary requirement of ribofla vin, as estimated by the more reliable urinary excretion method, was 1 .1-1.3 mg/d for those consuming the Western-type diet, which is simila r to values found over 40 y ago in young adults. We conclude that the dietary requirements of riboflavin in the elderly do not differ from t hose of young adults.