Higher vitamin A tied to better lung function in asthma

Clinical takeaway: The findings support checking vitamin A and D status in patients with asthma, but the study did not measure whether correcting a deficiency changes lung function.

Poor lung function predicts mortality whether or not someone has lung disease, so anything that tracks with preserving it in asthma is worth a look. Prior work on vitamins A and D was somewhat muddy, with both showing protective and harmful effects on asthma depending on dose and timing. This study tested the two vitamins' actual role by measuring circulating levels against lung function in more than 2,000 children and adults with asthma.

Across children and adults, vitamin A status tracked with lung function more reliably than vitamin D, which did so only in adults. Higher vitamin A corresponded with higher FEV1 and FVC in both cohorts. The vitamin D signal appeared in adults alone, where higher levels also tracked with better FEV1 and FVC but showed nothing in children. Among adults, vitamin D sufficiency, at least 30 ng/mL, tracked with less epigenetic ageing, and lower lung function lined up with faster ageing across all measures.

Researchers drew on two asthma cohorts, 1,165 children (GACRS, Costa Rica) and 1,041 adults (Mass General Brigham), measuring plasma vitamin A and serum vitamin D against FEV1 and FVC. In adults, they also assessed six epigenetic ageing clocks and ran mediation analysis on DNA methylation and microRNA.

These measurements are single-point and relative, the authors note, so they cannot track how vitamin levels and lung function move together over time. They call for repeated, absolute measures to clarify that dynamid. An accompanying editorial adds a sharper caution: vitamin D supplementation trials have not improved lung function in asthma, and the cross-sectional signal may partly reflect healthier behavior in people with higher levels.

"While these findings open a novel line of investigation linking vitamin D, biological ageing and lung health, there is a need for further studies to clarify causality," concludes a linked editorial.

Source: Sharma R, et al. (Jun 30 2026) Thorax. The impact of vitamins A and D on lung function and regulatory epigenetics in adult and childhood asthma