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New research suggests a strong relationship between prenatal vitamin A deficiency and postnatal asthma. More specifically, vitamin A deprivation during gestation may impact the smooth muscle of the airways, leading to asthmatic symptoms later in life.
Researchers at the Columbia University Medical Center deprived maternal mice of vitamin A during the point of gestation associated with fetal lung development. The research team found that the mouse fetus formed an excessive amount of smooth muscle around the airways. During another experiment, researchers deprived the mothers of vitamin A during the same developmental stage, but then returned them to a normal diet until the mouse pups grew into adults.
“When we examined these mice as adults we found that, although they looked normal and had normal levels of vitamin A, they had an exaggerated response to low doses of a chemical that causes bronchoconstriction, like an asthmatic person does,”said senior author Dr. Wellington Cardoso, director of the Columbia Center for Human Development and faculty member in the Division of Pulmonary Allergy Clinical Care Medicine.
According to Cardoso, none of these changes were seen in the mice that hadn’t been exposed to vitamin A deficiency in-utero.
“Vitamin A deficiency causes structural defects in the airways that are forming in the fetus, even if the vitamin A deficiency only happens for a very brief time,” said Cardoso, who added that this defect is carried throughout life.
Healthy levels of vitamin A during the neonatal or adult life showed no impact in reversing these effects in mice.
Cardoso and his team speculate that genetic factors do not act alone in causing asthma or COPD. Fetal exposure to adverse conditions at specific gestational stages may also play an important role. Previous studies have made the link between asthma and vitamin A, but this research has mostly been focused on postnatal life. For example, Cardoso explains that children who have deficiencies in vitamin A typically have more severe and more frequent asthma. Maternal vitamin A deficiency has also been tied to postnatal lung function, but the reasons were unclear.
“In the human fetus, the lungs start to form around the third week of gestation and by the second month, multiple generations of airways have already formed,” said Cardoso.
This particularly concerned researchers as many women don’t know they’re pregnant at this point. As a result, Cardoso says they may expose the fetus to agents like cigarette smoke or alcohol, which can interfere in crucial developmental events in ways that include vitamin A metabolism.
By Marianne Hayes