Having higher levels of vitamins A and D in the body could help improve lung function in adults with asthma, suggests research led by Brigham and Women’s Hospital in Boston.
The study, published in the journal Thorax, also showed that higher vitamin A levels could also benefit lung health in children with asthma.
“Vitamins A and D are key regulators of gene expression involved in lung development and immune function…Both vitamins have complex roles in asthma and lung function,” write lead author Michael McGeachie, PhD, assistant professor at Brigham and Women’s Hospital, and colleagues.
“Vitamin A deficiency is more common in people with asthma and is linked to airway hyperresponsiveness. Moderate intake in childhood may improve lung function and reduce asthma risk, whereas excessive intake may increase adult-onset asthma risk. Vitamin D deficiency is associated with poorer lung function, increased exacerbations and worse disease control, although results are variable due to diet, age and sun exposure.”
In this study, the researchers evaluated data from two asthma study cohorts—the Genetic Epidemiology of Asthma in Costa Rica Study including 1,165 children with asthma and the adult Omic Determinants of Longitudinal Lung Function in Asthma cohort including 1,041 adults with the condition.
The researchers looked at both circulating vitamin A and D in both groups and also looked at links with epigenetic regulation.
In children, there were no significant links between lung function and vitamin D levels. Higher vitamin A levels were linked to better breathing capacity though. For each step up in vitamin A levels, the amount of air the children could blow out in the first second was about 2.5 percentage points higher, and the total amount of air they could breathe out was about 7.6 percentage points higher.
In the adults, one step up in vitamin A levels was linked to a 4.7 unit increase in the amount of air they could blow out in the first second and a 3.4 unit increase in the total amount of air they could breathe out. The effect of vitamin D levels in this group was smaller, but statistically significant, with lung function improvements between 0.16-0.18 units per step up in vitamin D levels.
The researchers also looked at DNA methylation and at several epigenetic clocks that estimate a person’s biological age from methylation patterns in the adult cohort. They found that adults with higher vitamin A and vitamin D levels had fewer methylation tags at key control sites in the IRF5 gene than those with lower levels and showed changes in small regulatory micro RNAs that respond to vitamin levels. These epigenetic changes were linked to better lung function and slower biological aging.
The epigenetic tests suggest that vitamins influence lung function and aging partly by producing these epigenetic changes, rather than only through a direct effect, according to the researchers.
“While future studies to replicate these findings in independent populations are needed to confirm the generalizability and robustness of these observations,” write Sze Man Tse, MD, and Geneviève Mailhot, PhD, of the CHU Sainte-Justine Research Center, Montreal, and the University of Montreal in an accompanying editorial in the same journal, “subsequent interventional studies examining the impact of vitamin supplementation on biological ageing and on IRF5 function will be particularly relevant.”
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