About My Health Careers Internship MedBlogs Contact us
Medindia LOGIN REGISTER
Advertisement

Intake of Excess Vitamins During Pregnancy Will Be Passed to Developing Fetuses

by Medindia Content Team on October 10, 2007 at 11:46 AM
Font : A-A+

Intake of Excess Vitamins During Pregnancy Will Be Passed to Developing Fetuses

A new University of Wisconsin-Madison study suggests that pregnant women who take some types of vitamin supplements or eat fortified foods may be passing excess vitamin A to their developing fetuses. Reported in the October issue of the Journal of Comparative Medicine, the finding could guide efforts to develop future formulations of vitamins.

Best known as retinol because it produces the eye's retinal pigments, vitamin A is important for fetal development and to establish and maintain healthy lactation in breast-feeding mothers. For these reasons, many U.S. women are either prescribed or begin taking over-the-counter vitamin supplements during the first trimester of pregnancy.

Advertisement

However, it's still unclear how much vitamin A is too much, making it important to learn the levels at which vitamin A compounds - present as retinyl acetate and palmitate in supplements - begin affecting the early fetus, says UW-Madison nutrition professor Sherry Tanumihardjo.

"The high intake of vitamin A from supplements and fortified foods worldwide has caused us to be concerned," she says. With colleagues Ei Terasawa, professor of pediatrics in the School of Medicine and Public Health and the Wisconsin National Primate Research Center, and first author Jordan Mills, a nutritional sciences graduate student, Tanumihardjo has found that when mother monkeys consume excess vitamin A in fortified food, this results in increased storage of the vitamin - in a form called retinyl ester - in fetal livers during early gestational stages.
Advertisement

Liver storage may occur when vitamin A levels outstrip the immediate demands of the developing fetus, possibly as a way to protect against vitamin A toxicity. Tanumihardjo attributes the excess vitamin A to lab diets containing high concentrations of the vitamin. "Those diets should be reformulated," Tanumihardjo says. In addition, new vitamin A formulations for people might be developed that could still meet the needs of mother and fetus, while avoiding the problems that excess vitamin A might cause, she adds.

Previous data from human fetuses suggest that liver vitamin A concentrations increase until sometime in the third trimester. They then drop steadily until birth, after which the baby's consumption of breast milk causes them to rise again. But until now, early human data - or any primate data, for that matter - has been rare, says Tanumihardjo.

"Although data exist for late-stage fetal and neonatal liver vitamin A storage in humans and rodents, few data exist regarding early-stage fetal tissues of all species, including primates," she says. In addition to sharing approximately 95 percent genetic homology, Old World monkeys and humans exhibit comparable organ growth rates and sizes throughout fetal and postnatal development, making monkeys useful models for early human development.

In the study, the researchers obtained maternal diet information and necropsy tissue from the Primate Center for three Old World species: rhesus macaques, cynomolgus macaques, and vervets, to maximize study samples. They then used a series of chemical extraction and analysis techniques to measure relevant vitamin A compounds in tissue, including retinoic acid, retinol, and retinyl esters.

The excess vitamin A the researchers discovered in the monkeys didn't appear to cause problems, likely because the maternally derived vitamin A was stored primarily as relatively harmless retinyl esters in the liver, rather than being converted to harmful retinoids. This type of storage occurs either through fetal conversion of retinol to retinyl esters or direct transmission of retinyl esters from mother to fetus, or as a combination of these routes, Tanumihardjo says. Preferential shunting of maternally derived vitamin A to storage as retinyl esters may help protect against vitamin A toxicity in the fetus.

"Monkeys are less sensitive to the harmful effects of retinoic acid than are humans and rodents," Tanumihardjo says. "Our observations may explain why there have been no reports of vitamin A-induced birth defects in neonates from primate colonies that are fed the standardized commercial diets for monkeys, despite evidence of excess vitamin intake A by their mothers. This mechanism may be an adaptation to constant exposure to a lab diet high in vitamin A."

But have humans similarly adapted to protect their early fetuses from excess vitamin A concentrations? The new research indicates that this may be so; however, Tanumihardjo is eager to compare her monkey data to more human data, especially earlier in development.

The research was supported by the National Institutes of Health and the Wisconsin National Primate Research Center.

Source: UB-News Service

Source: IANS
LIN/M
Advertisement

Advertisement
News A-Z
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
Advertisement
News Category
What's New on Medindia
International Day of Persons with Disabilities 2021 - Fighting for Rights in the Post-COVID Era
Effect of Blood Group Type on COVID-19 Risk and Severity
Woman with Rare Spinal Cord Defect from Birth Sues Doctor
View all

Medindia Newsletters Subscribe to our Free Newsletters!
Terms & Conditions and Privacy Policy.

More News on:
Calcium and Vitamin Supplements Trimester of pregnancy Pregnancy and Exercise Home Pregnancy Test Pregnancy Psychological Changes In Pregnancy Vitamin Supplements Vitamin C / Ascorbic acid Vitamin B6 Vitamin B9 

Recommended Reading
Electronic Fetal Monitoring - Animation
Fetal monitoring records the condition of the fetus and contractions of the uterus during the ......
Low Vitamin D Levels Dangerous for Pregnant Women
One more study has proved the importance of vitamin D to pregnant women. If it is low, the women ......
Calcium and Vitamin Supplements
Calcium and vitamin supplements are taken to provide the body with the ''required'' nutrients. Calci...
Home Pregnancy Test
A home pregnancy test is a test done to find out if one is pregnant or not in the relative comforts ...
Pregnancy
Detailed look at Early pregnancy Symptoms and easy health solutions during 1st, 2nd and 3rd trimeste...
Psychological Changes In Pregnancy
Pregnancy is an experience of growth, change, enrichment and challenge. During the 40 weeks of pregn...
Trimester of pregnancy
Encyclopedia section of medindia explains in brief about confirmation of pregnancy in first ......
Vitamin B6
Vitamins play an equally important part in the synthesis of neurotransmitters. Neurotransmitters in ...
Vitamin B9
Vital info about vitamin B9, its molecular structure, dietary sources, beneficial aspects, symptoms ...
Vitamin C / Ascorbic acid
Vital info about vitamin C, its molecular structure, dietary sources, beneficial aspects, symptoms o...
Vitamin Supplements
Easy to understand info & tips with diagrams about vitamin supplements like vitamin C, B6, B9 & B12....

Disclaimer - All information and content on this site are for information and educational purposes only. The information should not be used for either diagnosis or treatment or both for any health related problem or disease. Always seek the advice of a qualified physician for medical diagnosis and treatment. Full Disclaimer

© All Rights Reserved 1997 - 2021

This site uses cookies to deliver our services. By using our site, you acknowledge that you have read and understand our Cookie Policy, Privacy Policy, and our Terms of Use