Dioxin impact on Vitamin A absorption
because a high intake of vitamin A in pregnancy has been associated
with developmental effects on the unborn child. However too low an
intake can also pose problems. A European-funded project in the
Netherlands set out to investigate the impact of pollutants in
foods on vitamin A levels in order to quantify the potential
toxicological risk to consumers.
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, because a high intake 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, it can be associated with potential risk to the foetus.
Further to reports of vitamin A depletion in animals as a result of exposure to organohalogen compounds (OH's) [OHs, such as dioxins and dioxin-like PCBs are toxic, persistent pollutants that occur in fat-rich food items, such as oily fish and liver, as residues] an EU-funded project, co-ordinated by Professor Dr Abraham Brouwer at the Institute for Environmental Studies, in the Netherlands, has investigated this effect to quantify the potential toxicological risk to consumers with the aim to provide a sound scientific basis to the risk.
The researchers report that contrary to most predictions, this study showed that OHs led to hypervitaminosis A (too much vitamin A) rather than a vitamin A deficiency syndrome in the animal studies carried out. 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 stress that the interpretation of these results in terms of risks for humans, in particular pregnant women, is not entirely warranted.
The scientists concluded from the project 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 intrinsically exacerbated by background levels of OHs. They advise to cautiously evaluate total retinoid uptake, and limit rather than further increase its uptake in populations where deficiency is not a problem.
Further information about project no: FAIR-CT97-3220 can be obtained from Professor Dr Abraham Brouwer - Bram.Brouwer@IVM.VU.nl