Twenty-four-hour urinary water-soluble vitamin levels correlate with their intakes in free-living Japanese schoolchildren

Abstract

AbstractObjectiveTo examine the association between 24 h urinary water-soluble vitamin levels and their intakes in free-living Japanese schoolchildren.DesignAll foods consumed for four consecutive days were recorded accurately by a weighed food record. A single 24 h urine sample was collected on the fourth day, and the urinary levels of water-soluble vitamins were measured.SettingAn elementary school in Inazawa City, Japan.SubjectsA total of 114 healthy, free-living, Japanese elementary-school children aged 10–12 years.ResultsThe urinary level of each water-soluble vitamin was correlated positively to its mean intake in the past 2–4 d (vitamin B1:r= 0·42,P< 0·001; vitamin B2:r= 0·43,P< 0·001; vitamin B6:r= 0·49,P< 0·001; niacin:r= 0·32,P< 0·001; niacin equivalents:r= 0·32,P< 0·001; pantothenic acid:r= 0·32,P< 0·001; folic acid:r= 0·27,P< 0·01; vitamin C:r= 0·39,P< 0.001), except for vitamin B12(r= 0·10,P= NS). Estimated mean intakes of water-soluble vitamins calculated using urinary levels and recovery rates were 97–102 % of their 3 d mean intake, except for vitamin B12(79 %).ConclusionsThe results show that urinary levels of water-soluble vitamins, except for vitamin B12, reflected their recent intakes in free-living Japanese schoolchildren and could be used as a potential biomarker to estimate mean vitamin intake.