Riboflavin supplementation in a resettlement village in north-east Thailand.

I. A high prevalence of biochemical ariboflavinosis was shown to be present in the preschool children and a small group of adults in a village in north-east Thailand using an in vitro test based on erythrocyte glutathione reductasc (EGR) activity. z. A riboflavin supplement of 10 mgld mas given to all subjects for 7 d. 3. It was demonstrated that the riboflavin supplement cured the biochemical ariboflavinosis and the results supported the prcvious suggestion that a stimulation 3 20 % of the in vitro EGR activity was a good indicator of ariboflavinosis. 4. A dietary survey carried out on twenty preschool children during the experimental period showed riboflavin intake to be low, 0.18 2 0.06 mg/Mcal. 5 . No glucose-6-phosphate dehydrogenase (G-6-PD)-deficient subjects were shown to be deficient in riboflavin by the in vitro test. The possibility of using in vivo stimulation of EGR activity by riboflavin is discussed as a possible way of demonstrating ariboflavinosis in G-6PD-deficient subjects.