In vitro estrogenic activity of cereal‐based products: Reliability and relevance considerations

Abstract

AbstractBackground and objectivesThe presence of endocrine disruptors in food is creating concern, and consequently, efficient methods for their identification are needed. In vitro bioassays have been developed to study endocrine properties of pure chemicals as well as mixtures. Because of their relative ease of execution and low cost, application of such techniques to whole foods is tempting. This raises a number of technical challenges. To address them, a study was commissioned in a contract laboratory offering in vitro estrogenicity testing of food products.FindingsFour different commercial and regulatory compliant cereal products were sent in blinded triplicates. Some samples were reported to be active by the laboratory. However, the results were not reproducible and very close to the 0% measurable activity. Furthermore, a statistical analysis of the raw data indicated an absence of activity. This was surprising since these products were expected to naturally contain estrogenic compounds such as the phytoestrogens lignans and flavones. However, phytoestrogens in cereals are known to occur mainly in bound, inactive, forms, suggesting that the sample preparation used in the present study was not suitable to release active estrogenic substances. This hypothesis was supported by preliminary data using a high‐resolution mass spectrometry method which did not detect any significant levels of phytoestrogens in the tested cereal extracts.ConclusionsUsing a yeast‐based method, no estrogenic activity was found in breakfast cereals. However, benchmarking the bioassay data against quality criteria raised the question of the qualification of the sample preparation and bioassay used to adequately address estrogenic activity of whole foods.Significance and noveltyThe quality requirements for testing whole food samples were formally addressed. The application of validated and harmonized methods for both sample preparation and bioassay testing is strongly advocated.