Vitamin A - finding the balance
consuming too much vitamin A.
Pregnant women are advised to avoid high doses of vitamin A, and to refrain from eating liver and liver products that are naturally high in vitamin A, following research carried out in the Netherlands.
Consuming large doses of vitamin A in pregnancy has been associated with developmental effects on the unborn child, however if the intake is too low, (a serious problem in developing countries), there could be a potential risk to the foetus.
Following reports of vitamin A depletion in animals as a result of exposure to organohalogen compounds (OHs), such as dioxins and dioxin-like PCBs which are toxic, persistent pollutants occurring in fat-rich food items such as oily fish and liver, an EU-funded project is studying the potential toxicological risk to consumers. The project is being co-ordinated by Professor Dr Abraham Brouwer at the Institute for Environmental Studies, in the Netherlands.
Researchers report that contrary to most predictions, this study has shown that OHs led to hypervitaminosis A (too much vitamin A) rather than a vitamin A deficiency syndrome in animal studies. The scientists suggested that the underlying mechanism involves a disturbed vitamin A (or retinoid) 'economy' and causes a net increase in retinoic acid levels.
However, it is worth noting that amounts of OHs used in the experiment were relatively high and the researchers stressed that further examination of these results, in particular concerning risks for pregnant women, was needed.
The scientists concluded that humans, in particular women of childbearing age, may be at risk of a marginal excess of vitamin A due to the combined effects of an increased intake in some functional foods, which can be exacerbated by background levels of OHs. They advised an evaluation of total retinoid uptake, and that people should limit rather than further increase uptake in populations where deficiency is not a problem.
Further information about the project, FAIR-CT97-3220, can be obtained from Professor Dr Abraham Brouwer at Oenz.Oebhjre@VIZ.IH.ay
