LINK BETWEEN NEW BORN HEALTH AND VITAMIN D
The impact vitamin A
has on newborns is virtually unknown, but Penn State nutrition researchers have
published two papers that may provide a framework for future investigations of
the vitamin and neonatal health.
After supplementing
newborn rats with vitamin A, the researchers found that vitamin A distribution
within the body increases suddenly but temporarily, with a significant amount
found in tissues other than the liver. Vitamin A in adults is usually found in
significant amounts in the liver.
Nutrition experts know
that vitamin A is necessary for prenatal growth and development, as well as in
older children; but the role of vitamin A remains unclear for the neonatal
period. Stores of the vitamin become depleted as the fetus reaches full term,
to the point where newborns are nearly depleted of vitamin A. Neonates born in
developing countries are likely to have even lower amounts of vitamin A in
their bodies.
"The World Health
Organization recommends periodic vitamin A supplements to children living in
developing countries," said A. Catharine Ross, professor of nutritional
sciences and Dorothy Foehr Huck Chair. "Giving large doses of vitamin A to
children 6 months to 5 years old has shown to decrease mortality by 23 percent.
However, studies in children under 6 months have been inconclusive."
Ross and colleagues
studied levels of vitamin A in rat pups for two weeks, from 4 days old to 18
days old, similar to neonatal age in children. Half the pups received a vitamin
A supplement while the others did not receive any supplement -- serving as the
control.
The researchers
measured the pups' rate of vitamin A metabolism by sampling various organs and
found that vitamin A was used very quickly. Retinol, which is a form that
vitamin A takes in the body, isn't broken down immediately and is recycled
between plasma and tissues. The pups that received the supplement experienced
lower rates of recycling, however they had greater uptake of vitamin A in extravascular
tissues.
The supplemented rats
were also found to have an increased uptake of chylomicron retinyl ester --
another form that vitamin A takes in the body -- in the lungs, intestines and
remaining tissue, and a decrease in retinol turnover out of the liver, compared
to the unsupplemented rats, Ross and colleagues report in two recent articles
published in the Journal of Lipid Research.
The researchers
speculate that since the neonates are born with a low vitamin A level but have
a high demand for it, the uptake of retinyl ester in tissues other than the
liver is an adaptive mechanism to make more vitamin A available for use.
"This research
provides us with a blueprint for humans, giving us a baseline set of data, in
order to let us make comparisons in the future," said Ross. "By being
able to better understand infants' nutritional needs, evidence-based dietary
intake recommendations could be made and infant mortality could potentially be
reduced, particularly in developing countries."
Also working on this
research were Libo Tan, graduate student and postdoctoral fellow in nutritional
sciences; Amanda E. Wray, research technologist in nutritional sciences; and
Michael H. Green, professor of nutritional sciences.
Comments
Post a Comment