| Vitamin A for Fetal Development |
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| Written by Mary G. Enig, PhD |
| 2005-Nov-12 |
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True vitamin A is a vitamin that occurs only in animal fats. In primitive societies, pregnant women consumed special foods rich in vitamin A--such as liver, spring butter and fish eggs--in a conscious effort to produce healthy, well-formed children. Modern research completely validates these traditions. In a recent paper,1 Maija H. Zile, of the Department of Food Science and Human Nutrition, Michigan State University, details the role of vitamin A in fetal development. Working with bird and mouse embryos, she and other researchers have determined that the vitamin A requirement begins at the time of formation of the primitive heart and circulation, and the development of the hindbrain, a period that corresponds to weeks 2-3 in humans. Without vitamin A, the embryo succumbs to gross abnormalities of the heart and is aborted. Each organ system begins development during a specific window of time. Vitamin A regulates the differentiation of the primitive cells into cells specific to each organ system, in essence signaling to the genes their marching orders so they "know" where to locate themselves and what kind of tissues to become. If vitamin A is lacking during any of these windows, the organs develop abnormally or not at all. The major target tissues of vitamin A deficiency include the heart, central nervous system, the circulatory, urogenital and respiratory systems, and the development of the skull, skeleton and limbs. Vitamin A deficiencies during the period when any of these systems begin specialization can result in abnormalities and defects. According to Zile, even partial vitamin A deficiency affects the sensitive developing central nervous system; it plays a key role in the development of the visual system, the retina, the inner ear, the spinal cord, the craniofacial area including the pharyngeal and branchial arches and the thymus, thyroid and parathyroid glands. During mid-gestation, vitamin A is required for fetal lung development. In vitamin A-deficient animals, congenital malformations in the urogential system occur. Another fascinating avenue of research has shown that vitamin A holds the key to what scientists call the "holy grail" puzzle of developmental biology: the existence of a mechanism that ensures that the exterior of our bodies is symmetrical while the inner organs are arranged asymmetrically. Researchers at the Salk Institute have found that vitamin A provides the signal that buffers the influences of asymmetric cues in the early stages of development, and allows these cells to develop symmetrically. In the absence of vitamin A, the exterior of our bodies would develop asymmetrically, with the result being that our right side would be shorter than the left side.3 After the formation of all the organ systems, vitamin A supports their growth. Chronic vitamin A deficiency during pregnancy compromises the liver, heart and kidney and impairs lung growth and development during the last weeks of gestation.4 Unfortunately, FDA and other agencies warn pregnant women to avoid foods like liver and cod liver oil, claiming that too much vitamin A from these foods can cause birth defects. The study usually cited in support of these warnings was carried out in 1995 at the Boston University School of Medicine and published in the New England Journal of Medicine.5 In the study, researchers asked over 22,000 women to respond to questionnaires about their eating habits and supplement intake before and during pregnancy. Researchers found that cranial-neural crest defects increased with increased dosages of vitamin A; but neural tube defects decreased with increased vitamin A consumption, and no trend was apparent with musculoskeletal, urogenital or other defects. This study is a poor rack on which to hang the myriad warnings that have kept pregnant women from eating liver and taking cod liver oil. Researchers made no distinction between synthetic vitamin A derived from multivitamins and processed food like margarine, and natural vitamin A from food; nor did they take blood samples to determine vitamin A status. Food recall surveys are a notoriously inaccurate method of determining nutrient intake. Subsequent studies found that high levels of vitamin A did not increase the risk of birth defects. A 1998 study from Switzerland looked at vitamin A in pregnant women and found that a dose of 30,000 IU per day resulted in blood levels that had no association with birth defects.6 A 1999 study carried out in Rome, Italy found no congenital malformations among 120 infants whose mothers consumed an average of 50,000 IU of vitamin A per day.7 Some participants consumed up to 300,000 IU vitamin A daily during pregnancy with no birth defects in the offspring. An average of 50,000 IU vitamin A per day is consistent with our recommendation of cod liver oil to supply 20,000 IU per day plus additional vitamin A in liver, butter, seafood and egg yolks.
About the Author
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Mary G. Enig, PhD is an expert of international renown in the field of lipid biochemistry. She has headed a number of studies on the content and effects of trans fatty acids in America and Israel, and has successfully challenged government assertions that dietary animal fat causes cancer and heart disease. Recent scientific and media attention on the possible adverse health effects of trans fatty acids has brought increased attention to her work. She is a licensed nutritionist, certified by the Certification Board for Nutrition Specialists, a qualified expert witness, nutrition consultant to individuals, industry and state and federal governments, contributing editor to a number of scientific publications, Fellow of the American College of Nutrition and President of the Maryland Nutritionists Association. She is the author of over 60 technical papers and presentations, as well as a popular lecturer. Dr. Enig is currently working on the exploratory development of an adjunct therapy for AIDS using complete medium chain saturated fatty acids from whole foods. She is Vice-President of the Weston A Price Foundation and Scientific Editor of Wise Traditions as well as the author of Know Your Fats: The Complete Primer for Understanding the Nutrition of Fats, Oils, and Cholesterol, Bethesda Press, May 2000. She is the mother of three healthy children brought up on whole foods including butter, cream, eggs and meat.
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My daughter was diagnosed at four months with vesicourinary or vesicoureteral reflux. Additionally, the doctor found from the scans they did of her urinary system that her right kidney was significantly smaller than her left. Eventually the left side corrected itself without surgery but she required a procedure to reinsert the ureter on the right side.
I'm very suspicious that my diet during my pregnancy is the culprit. But what they tell us when our child is diagnosed with this thing is that they think it's genetic. They say it runs in families and that if one child has it there is a thirty percent chance other children in the family will have it.
I wonder. Dr. Price noticed a relationship between birth order and stunted development due to poor nutrition. I wouldn't be surprised if this were related too. If a first child were to suffer from VUR due to poor nutrition, it only stands to reason the subsequent children have a greater chance of it if the mother doesn't correct her nutrition.
I wish your work were more widely known. Kidney failure is so common in our country that the need for dialysis is one of the major trigger events that qualifies an American citizen for Medicare. Imagine all the money and pain and sorrow and shortened lives we would spare if people would just eat more liver.