Higher Vitamin Levels Boost Lung Function in Asthma

Higher Vitamin Levels Boost Lung Function in Asthma

Higher levels of circulating vitamin A are linked to better lung function in both children and adults with asthma, while vitamin D provides similar benefits for adults, including a reduction in biological ageing. The findings, published this week in the respiratory journal Thorax, are described by researchers as the first study of its kind to integrate vitamin levels with lung function and epigenetic markers.

The research, led by Boston’s Brigham and Women’s Hospital, utilized two distinct study cohorts: 1,165 children participating in the Genetic Epidemiology of Asthma in Costa Rica Study (GACRS) and 1,041 adults in the Omic Determinants of Longitudinal Lung Function in Asthma (ODOLLFA).

Impact on Lung Capacity

To assess respiratory health, researchers measured forced vital capacity (FVC), forced expiratory volume in 1 second (FEV1), and the FEV:FVC ratio. For children, the study found no significant link between lung function and vitamin D levels; however, higher vitamin A levels were associated with superior breathing capacity. Specifically, for each step up in vitamin A levels, the total amount of air children could breathe out was about 7.6 percentage points higher, and the amount blown out in the first second was about 2.5 percentage points higher.

In the adult group, a step increase in vitamin A linked to a 4.7 unit increase in the amount of air blown out in the first second and a 3.4 unit increase in total air breathed out. Vitamin D also showed a statistically significant, though smaller, effect in adults, with improvements between 0.16-0.18 units per step up.

Researchers noted that adults with asthma and vitamin D levels of at least 30 ng/ml demonstrated better lung function than those with lower levels. Conversely, vitamin D deficiency was more common among asthma patients and was associated with:

• More severe disease and worse asthma control
• A need for higher doses of inhaled steroids
• More frequent sudden worsening of asthma symptoms

Epigenetics and Biological Ageing

The study explored how vitamins influence the body through epigenetic mechanisms, specifically DNA methylation (which marks genes as active or inactive) and serum microRNAs (miRNAs), which fine-tune gene activity. Researchers identified miRNAs that regulate 248 genes associated with vitamins A and D, which likely play a role in controlling inflammation and lung function.

In adults, those with higher levels of vitamins A and D had fewer methylation tags at key control sites in the IRF5 gene. These epigenetic changes were linked to slower biological ageing. The researchers concluded that lung function was inversely correlated with all age acceleration measures, suggesting that adequate vitamin D may help slow age-related processes in people with asthma.

Lead author Michael McGeachie, PhD, assistant professor at Brigham and Women’s Hospital, and colleagues wrote that vitamins A and D are key regulators of gene expression involved in lung development and immune function. However, they noted a complex relationship: while moderate vitamin A intake in childhood may reduce asthma risk, excessive intake could increase the risk of adult-onset asthma.

Clinical Perspective and Future Research

The results have drawn a nuanced response from the medical community. In an editorial for Thorax, Dr Sze Man Tse and Dr Genevieve Mailhot of the University of Montreal stated that the findings reveal a nuanced interplay between vitamins A and D, lung function, and their epigenetic mediators. While they noted that understanding nutritional impacts on gene regulation could open new avenues for lifelong asthma management, they cautioned that there is a need for further studies to clarify causality.

The complexity of vitamin D's role is further highlighted by conflicting previous data. A 2016 Cochrane review of nine clinical trials suggested that vitamin D supplements could cut the risk of severe asthma attacks and the need for steroid treatment. However, an updated Cochrane review in 2023 found no evidence that vitamin D supplementation reduced the risk of exacerbations or improved asthma control.

The authors of the current study suggest that their findings point toward potential targets for personalised nutrition and therapeutic strategies in asthma care. Next steps for the field include interventional studies to examine the specific impact of vitamin supplementation on IRF5 function and biological ageing.