Book with abstracts from the COST Action 0905 meeting in ... - UMB

ARSENIC IN RICE: GASTROINTESTINAL BIOACCESSIBILITY
AND SPECIATION ARE AFFECTED BY FOOD MATRIX
Gijs Du Laing 1 , Pradeep Alava 1 , Filip Tack 1 , Tom van de Wiele 2
1 Laboratory of Analytical Chemistry and Applied Ecochemistry,
2 Laboratory of Microbial Ecology and Technology, Faculty of Bioscience Engineering,
Ghent University,
Coupure Links 653, B-9000 Gent, Belgium.
E-mail: Gijs.DuLaing@UGent.be
Rice significantly contributes to As uptake in Asian and Western diets. Several factors and
processes may affect As bioaccessibility, bioavailability, speciation and toxicity upon rice
ingestion. We assessed effects of the food matrix differing between diets. Two different
matrices containing As-polluted rice were subjected in vitro to gastrointestinal digestion
processes: a Western diet matrix high in fat and protein, and an Asian diet matrix low in fat
and protein but high in carbohydrates. Gastrointestinal digestion processes were mimicked
using the IVG method to which a colon digestion step was added. For use in colon
incubations, microorganisms were grown in a validated simulator of the human intestinal
microbial ecosystem, i.e. the SHIME system. In the Asian diet matrix, 85% of As was
released from the rice matrix into the liquid fraction of the stomach and small intestine, and
assumed to be bioaccessible. The remaining 15% is considered to move towards the colon.
In the Western diet matrix, the bioaccessible fraction amounted to only 65%, suggesting
that rice As will be less bioaccessible in presence of fat. In this diet, however, more As will
move towards the colon and be transformed by colon microorganisms. Colon incubations
reveal preferential formation of more toxic species (MMA III and MMTA V ) in the Western
diet.