Vitamin A rich diet essential for proper lung formation
New York, Feb 13 - In a significant breakthrough, the short-term deficit of vitamin A while the lungs are being formed in the baby during pregnancy has been linked to asthma later in life.
A team of Columbia University researchers has found the first direct evidence of a link between prenatal vitamin A deficiency and postnatal airway hyperresponsiveness - a hallmark of asthma.
The vitamin A deficiency can cause profound changes in the smooth muscle that surrounds the airways - causing the adult lungs to respond to environmental or pharmacological stimuli with excessive narrowing of airways, say Columbia University Medical Center (CUMC) investigators led by Wellington V. Cardoso.
â€śResearchers have long wondered what makes some people more susceptible than others to developing asthma symptoms when exposed to the same stimulus,â€ť added Cardoso, faculty member in the division of pulmonary allergy clinical care medicine.
Our study suggests that the presence of structural and functional abnormalities in the lungs due to vitamin A deficiency during development is an important and under-appreciated factor in this susceptibility, he stressed.
Previous studies had shown that retinoic acid (RA) - the active metabolite of vitamin A - is essential for normal lung development.
The researchers used a mouse model in which they could control when and in what amount vitamin A would reach the developing foetus through maternal diet.
They timed the vitamin A deficiency to the middle of gestation, coinciding with the period of formation of the airway tree in the foetus.
Foetuses that were deprived of vitamin A were found to have excess smooth muscle in the airways, compared with control groups.
In a subsequent experiment, the mice were again deprived of vitamin A during the same developmental stage, but returned to a normal diet after that stage and until adulthood.
"When the animals reached adulthood, they appeared normal; they had no problems typically associated with vitamin A deficiency,â€ť explained Cardoso.
However, pulmonary function tests showed that their lungs were clearly not normal.
When the mice were challenged with methacholine, a chemical that causes the airway to contract, their response was significantly more severe than that of controls.
The findings underscore the importance of sufficient vitamin A in the diet, which remains a significant challenge in developing countries, including India. (IANS)