Pregnancy: Vitamin A deficiency damages children's lungs

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MunichHow the expectant mother feeds herself has an impact on the later health of her child. It has now been shown for the first time that vitamin A also plays an important role here. If the pregnant woman suffers from a deficiency at the wrong time, this can affect the lungs of the offspring. Too much muscle is to blame.

"We have long wondered why some people are more prone to developing asthma than others," explains Dr. Wellington Cardoso from Columbia University. Scientists approached this question from a new angle. They examined mice as model organisms because they could precisely control when and how much vitamin A the animals consumed. “We put the vitamin A deficiency roughly in the middle of the wearing time because the airways develop in the fetus during this period,” says Cardoso. Subsequently, the supply of sufficient vitamin A was ensured again until adulthood.

Hypersensitive bronchi

The deficiency in the womb left clear traces: the rodents appeared quite ordinary on the outside. "But respiratory function tests made it clear that her lungs were anything but normal," said the study director. The researchers performed a provocation test with methacholine - a drug that narrows the airways for a short time. This is used to analyze whether the bronchial system is overly sensitive, for example with a cough or shortness of breath. Here, too, the animals that had suffered a vitamin A deficiency as a fetus showed significantly stronger reactions than comparison animals.

Smooth muscles proliferate without vitamin A.

Additional experiments were also able to clarify the mechanism behind the fatal effects of too little vitamin A in pregnancy. As the lungs develop, new branches of the airways grow out of the bronchi. These branches are surrounded by smooth muscles. A specific messenger substance temporarily stops the growth of the smooth muscles so that too much of it is not formed and possibly hindered later breathing. This signal substance is a metabolic product of vitamin A - retinoic acids. And indeed: the animals that had experienced a vitamin A deficiency in the womb had abnormally large amounts of smooth muscle in the airways. These changes can also be seen in asthma patients, for example.

Susceptible to interference

Their results underline the need for an adequate supply of vitamin A during pregnancy. Although this is not necessarily a problem in Western countries, according to the scientists, it is possible that there are factors that prevent the fetuses from being able to use vitamin A sufficiently. “The body has a very complex system for utilizing vitamin A. And that is very sensitive to external disturbances, for example in the form of cigarette smoke or alcohol, ”explains Cardoso. For this reason, more extensive research is necessary, especially in order to better understand the effect of these environmental factors on unborn life.

Occurrence in food of animal origin

Vitamin A is a fat-soluble vitamin. Among other things, it plays an important role in the human body when it comes to seeing in dim light, as a protective factor for the skin or in the regulation of bone growth. Vitamin A is found mainly in foods of animal origin, especially liver. It is also contained in precursors (carotenoids) in plants, for example carrots. (lh)

Source: F. Chen et al. Prenatal retinoid deficiency leads to airway hyperresponsiveness in adult mice. J Clin Invest. 2014; 124: 801-811. doi: 10.1172 / JCI70291.

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