Teratogenicity of high vitamin A intake

Article Abstract:

Consumption of high levels of retinol by women immediately before and during pregnancy may lead to birth defects. Retinol is the form in which vitamin A is stored in mammals. Researchers interviewed 22,748 pregnant women and studied the occurrence of birth defects originating from the cranial-neural-crest of the embryo. A total of 339 babies were born with birth defects. Women who consumed more than 15,000 international units of retinol a day (IU/day) were 3.5 times more likely to have babies with cranial-neural-crest defects than women who consumed less than 5,000 IU/day. For retinol consumed in dietary supplements alone, women who took more than 10,000 IU/day were 4.8 times more likely to have babies with cranial-neural-crest defects than women who took less than 5,000 IU/day. To a lesser extent high retinol consumption was associated with other types of birth defects. Statistical analysis showed that consumption of retinol from supplements of over 10,000 IU/day led to a probability that 1 in 57 babies would be born with a defect linked to the vitamin.

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Vitamin A and birth defects: continuing caution is needed

Article Abstract:

Around the time of conception, women should limit their consumption of vitamin A to 8000 International Units (IU) a day and consume 0.4 milligrams of folic acid to reduce the risk of birth defects. Various health agencies have recommended that women and vitamin manufacturers heed these guidelines. Various studies have found that multivitamins with folic acid and vitamin A may reduce birth defects, but high doses of vitamin A may lead to birth defects. However, studies have not consistently recommended or warned about specific doses of vitamin A. A 1995 study found that vitamin A was safe in doses less than 10,000 IU a day, but increased the risk of birth defects in larger doses. However the graph in this study that relates birth defects to specific vitamin A doses may not be reliable in advising pregnant women of their risk level based on dose. Women may receive a safe dose of vitamin A and a sufficient dose of folic acid by carefully selecting appropriate vitamin supplements and avoiding consumption of large amounts of liver products.

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Urgent need to increase folic acid consumption

Article Abstract:

The use of supplemental folic acid is urged to reduce the incidence of spina bifida and anencephaly. Folic acid vitamin supplements or food fortification can prevent at least half of the cases of these types of birth defects. The optimum public health strategy appears to be food fortification, but it should equal at least double the average red cell folate level in women, which is an extra 0.4 mg of folic acid daily. Total folic acid consumption among women of reproductive age should not exceed 1.0 mg daily because it could mask a vitamin B12 deficiency. This deficiency needs to be detected and treated in pregnancy to avoid possible neurological damage to the baby. Consumption of adequate folic acid is important for everyone. A folic acid deficiency also can cause occlusive cardiovascular disease.

Usage, Abnormalities, Folic acid, Neural tube, Neural tube defects

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