Suppressive Effect of Apple Juice Intake on Urinary Excretion of Ascorbic Acid: Unblinded Randomized Crossover Study in Healthy Japanese Subjects

Ascorbic acid is essential for human health. As this vitamin is water-soluble, it cannot be stored in the body for a long time and is easily excreted in urine; therefore, it is necessary to ingest it in sufficient amounts every day. The fact that apples retain ascorbic acid in human bodies are known; however, this has not been experimentally demonstrated/documented. In this study, to clarify the effect of apple juice ingestion on the urinary excretion of ascorbic acid, we compared urinary ascorbic acid excretion in healthy women administered ascorbic acid alone or with apple juice. The experimental design was an unblinded randomized crossover study. Subjects ingested ascorbic acid in apple juice or ascorbic acid with water. Urine was collected after ingestion, and urinary ascorbic acid was measured. When ascorbic acid was ingested with apple juice, urinary excretion of ascorbic acid was significantly suppressed compared to when ascorbic acid was ingested alone. This suggests that apple juice intake can help retain ascorbic acid in the body.