This study quantifies a linear inverse dose-response relationship between serum vitamin A and anemia risk in Chinese children, providing evidence that the association spans the physiological range beyond clinical deficiency. It is the first to report a statistically significant "sex x vitamin A" interaction, revealing a notably stronger inverse association in males than in females. This novel finding highlights the need for further research into potential sex-specific biological pathways and may inform the design of more nuanced epidemiological and public health investigations.
Sun et al. (2026) studied this question.