The present invention provides a novel ascorbic acid derivative as a provitamin C with improved stability in the body and prolonged life in the body compared to conventionally known 2-O-(.alpha.-D-glucopyranosyl)ascorbic acid. The composition comprising the novel compound 2-O-(.beta.-D-glucopyranosyl)ascorbic acid has been extracted from plants such as from Ningxia Lycium barbarum L. and/or Lycium chinense Mill. The compositions comprising 2-O-(.beta.-D-glucopyranosyl)ascorbic acid may be enzymatically synthesized using .beta.-D-glucosyltransferase. Pure 2-O-(.beta.-D-glucopyranosyl)ascorbic acid may be produced from such compositions. Alternatively, 2-O-(.beta.-D-glucopyranosyl)ascorbic acid may be produced by chemical synthesis. The 2-O-(.beta.-D-glucopyranosyl)ascorbic acid results in higher stability and a prolonged life of vitamin C when ingested in the body compared to the corresponding .alpha.-D-glucopyranosyl derivative, and is therefore highly suitable as a provitamin C to be used in cosmetics and foods.