Study on Vitamin A Requirement of Adult Chinese by Isotope Dilution Technique and Vitamin A Intervention Trial

Abstract

The goal of this study is to determine dietary vitamin A requirement for keeping constant vitamin A pool in body in Chinese population. Total 116 healthy adult volunteers (half by genders) were recruited and divided into 4 groups and given vitamin A supplementation with different doses of 0μg/d, 200μg/d, 400μg/d and 600μg/d retinol (by retinyl acetate) for 4 months while they kept low vitamin A diets. Before and after vitamin A intervention, the liver vitamin A storages were determined by two metabolically dynamic experiments with the stable isotope dilution technique using 2H4‐and 2H8‐retinyl acetate. Three 24‐hours dietary recall were carried out once a month to survey background dietary vitamin A intake. The average vitamin A liver storage before and after intervention were (730.75±414.45) μmole and (934.59±786.61) μmole respectively. Average changes of liver vitamin A storage were (203.84±705.49) μmole for all subjects. The linear regression analysis on the data from total 104 subjects (52 males and 52 females) who finished the study showed that the predicted values of dietary vitamin A intake for maintaining total liver vitamin A storage unchanged was about 748.32μg Retinol Equivalents (RE) or 560.79μg Retinol Active Equivalents (RAE) in men, and 599.91μg RE or 472.19μg RAE in women. The values could be used as Estimated Average Requirement (EAR) of vitamin A for adult Chinese.