Page 51 - Special Issue: Healthy Baby

Know Your Fats

VITAMIN A FOR FETAL DEVELOPMENT
By Mary G. Enig, PhD

True vitamin A is a vitamin that occurs only During mid-gestation, vitamin A is required
in animal fats. In primitive societies, pregnant for fetal lung development. In vitamin A-defi-
women consumed special foods rich in vitamin cient animals, congenital malformations in the
A—such as liver, spring butter and fish eggs—in urogential system occur.
a conscious effort to produce healthy, well- Most interesting is new research on the effect
formed children. Modern research completely of vitamin A on kidney development. Vitamin A
validates these traditions. deficiency results in a reduced number of neph-
In a 2001 paper, Maija H. Zile of the De- rons in the kidney. Lower numbers of nephrons
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partment of Food Science and Human Nutrition, mean the kidneys will not work at optimal levels
Michigan State University, details the role of vi- and may doom the individual to dialysis later in
tamin A in fetal development. Working with bird life. 2
and mouse embryos, she and other researchers Another fascinating avenue of research
have determined that the vitamin A requirement has shown that vitamin A holds the key to what
begins at the time of formation of the primitive scientists call the “holy grail” puzzle of devel- Vitamin A

heart and circulation, and the development of the opmental biology: the existence of a mechanism regulates the
hindbrain, a period that corresponds to weeks that ensures that the exterior of our bodies is differentiation
2-3 in humans. Without vitamin A, the embryo symmetrical while the inner organs are arranged
succumbs to gross abnormalities of the heart and asymmetrically. Researchers at the Salk Institute of the
is aborted. have found that vitamin A provides the signal that primitive cells
Each organ system begins development buffers the influences of asymmetric cues in the into cells
during a specific window of time. Vitamin A regu- early stages of development, and allows these
lates the differentiation of the primitive cells into cells to develop symmetrically. In the absence specific to
cells specific to each organ system, in essence of vitamin A, the exterior of our bodies would each organ
signaling to the genes their marching orders so develop asymmetrically, with the result being system, in
they “know” where to locate themselves and what that our right side would be shorter than the left
kind of tissues to become. If vitamin A is lacking side. 3 essence
during any of these windows, the organs develop After the formation of all the organ systems, signaling to
abnormally or not at all. vitamin A supports their growth. Chronic vitamin the genes
The major target tissues of vitamin A de- A deficiency during pregnancy compromises the
ficiency include the heart, the central nervous liver, heart and kidney and impairs lung growth their
system, the circulatory, urogenital and respiratory and development during the last weeks of gesta- marching
systems, and the development of the skull, skele- tion. orders so
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ton and limbs. Vitamin A deficiencies during the Unfortunately, the FDA and other agencies
period when any of these systems begin special- warn pregnant women to avoid foods like liver they “know”
ization can result in abnormalities and defects. and cod liver oil, claiming that too much vitamin where to
According to Zile, even partial vitamin A from these foods can cause birth defects. The locate
A deficiency affects the sensitive developing study usually cited in support of these warnings
central nervous system; it plays a key role in the was carried out in 1995 at the Boston University themselves
development of the visual system, the retina, the School of Medicine and published in The New and what
inner ear, the spinal cord, the craniofacial area England Journal of Medicine. In the study, re- kind of tissues
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including the pharyngeal and branchial arches searchers asked over 22,000 women to respond
and the thymus, thyroid and parathyroid glands. (Continued on page 53) to become.

Wise Traditions 49