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Is there a risk of vitamin A toxicity for the fetus?

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By : Nurturing Life's Nutrition Team | Montreal Diet Dispensary
Vitamines A

Yes, but if and only if vitamin A as retinol is present in very large quantities. Vitamin A is essential for proper development of the unborn baby. However, an overdose of vitamin A can be toxic to the mother and the fetus.

Vitamin A, also called retinol, plays many roles in the body. It is essential for good night vision and contributes to a healthy skin, normal growth and a good immune system. Moreover, this vitamin could help prevent anemia in pregnant women.

Vitamin A is found in many foods including offal, fish, milk, certain dairy products and eggs. Fruits and vegetables, especially those of orange or dark green color, contain another form of vitamin A called beta-carotene. The latter is converted into retinol by the body.

However, vitamin A as retinol can be toxic when taken in large quantities, especially for the fetus in which the risk of birth defects in the case of such an overdose is well documented. However, there are no toxic effects associated with beta-carotene since the body converts it into vitamin A (retinol) only as needed (i.e., no need to limit the consumption of fruits and vegetables!).

As far as food products go, there is only liver that must be limited during pregnancy because its retinol content is very high (this includes cod liver oil). In light of recent studies, the Dispensary recommends avoiding liver consumption before the 12th week of pregnancy, and afterwards to limit the consumption to one serving of 75 g per week. This recommendation will be explained in the next edition. There is no risk associated with the consumption of other foods that contain vitamin A as retinol (see the foods mentioned above).

In general, the prenatal supplements do not exceed the maximum permitted amount of retinol per day. It is also very important, for any prenatal multivitamin, not to exceed the recommended dosage on the label without prior medical advice.

References

  • Directives cliniques de la SOGC (2003). L’apport en acide folique pour la prévention des anomalies du tube neural et d’autres anomalies congénitales. Journal des obstétriciens et gynécologues du Canada, 25(11), 966-973.
  • Grune, T., Lietz, G., Palou, A., Ross, A.C. et coll. (2010). B-carotene is an important vitamin A source for humans. The Journal of Nutrition, 140(12), 2268S-2285S. Doi: 10.3945/jn.109.119024
  • Hamdy, A.M., Abdel Aleem, M.M. et El-Shazly, A.A. (2013). Maternal vitamin A deficiency during pregnancy and its relation with maternal and neonatal hemoglobin concentrations among poor Egyptian families. ISRN Pediatrics, 2013, 1-6.
  • Hendricks, A.G. et Hummler, H. (1992). Teratogenicity of all-trans retinoic acid during early embryonic development in the cynomolgus monkey (macaca fascicularis). Teratology 45(1), 65-74
  • Lynberg, M.C., Khoury, M.J, Lammer, E.J. et coll. (1990). Sensitivity, specificity, and positive predictive value of multiple malformations in isotretinoin embryopathie surveillance. Teratology 42(5), 513-519.
  • Santé Canada. (2006). Apports nutritionnels de référence. http://www.hc-sc.gc.ca/fn-an/alt_formats/hpfb-dgpsa/pdf/nutrition/dri_tables-fra.pdf
  • Thorne-Lyman A.L et Fawzi, W.W. (2012). Vitamin A and carotenoids during pregnancy and maternal, neonatal and infant health outcomes: a systematic review and meta-analysis. Pediatric and Perinatal Epidemiology, 26(Suppl. 1), 36-54.

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The views expressed herein do not necessarily represent the official views of the Public Health Agency of Canada.