Many natural chemicals in food are in the nanometer size range, and the selective uptake of nutrients with nanoscale dimensions by the gastrointestinal (GI) tract is a normal physiological process. Novel engineered nanomaterials (NMs) can bring various benefits to food, e.g., enhancing nutrition. Assessing potential risks requires an understanding of the stability of these entities in the GI lumen, and an understanding of whether or not they can be absorbed and thus become systemically available. Data are emerging on the mammalian in vivo absorption of engineered NMs composed of chemicals with a range of properties, including metal, mineral, biochemical macromolecules, and lipid‐based entities. In vitro and in silico fluid incubation data has also provided some evidence of changes in particle stability, aggregation, and surface properties following interaction with luminal factors present in the GI tract. The variables include physical forces, osmotic concentration, pH, digestive enzymes, other food, and endogenous biochemicals, and commensal microbes. Further research is required to fill remaining data gaps on the effects of these parameters on NM integrity, physicochemical properties, and GI absorption. Knowledge of the most influential luminal parameters will be essential when developing models of the GI tract to quantify the percent absorption of food‐relevant engineered NMs for risk assessment. WIREs Nanomed Nanobiotechnol 2015, 7:609–622. doi: 10.1002/wnan.1333For further resources related to this article, please visit the WIREs website.

Abstract:The NanoRelease Food Additive project developed a catalog to identify potential engineered nanomaterials (ENMs) used as ingredients, using various food-related databases. To avoid ongoing debate on defining the term nanomaterial, NanoRelease did not use any specific definition other than the ingredient is not naturally part of the food chain, and its dimensions are measured in the nanoscale. Potential nanomaterials were categorized based on physical similarity; analysis indicated that the range of ENMs declared as being in the food chain was limited. Much of the catalog's information was obtained from product labeling, likely resulting in both underreporting (inconsistent or absent requirements for labeling) and/or overreporting (inability to validate entries, or the term nano was used, although no ENM material was present). Three categories of ingredients were identified: emulsions, dispersions, and their watersoluble powdered preparations (including lipid-based structures); solid encapsulates (solid structures containing an active material); and metallic or other inorganic particles. Although much is known regarding the physical/chemical properties for these ingredient categories, it is critical to understand whether these properties undergo changes following their interaction with food matrices during preparation and storage. It is also important to determine whether free ENMs are likely to be present within the gastrointestinal tract and whether uptake of ENMs may occur in their nanoform physical state. A practical decision-making scheme was developed to help manage testing requirements.

This article is one of a series of 4 that report on a task of the NanoRelease Food Additive (NRFA) project of the International. Life Science Institute Center for Risk Science Innovation and Application. The project aims are to identify, evaluate, and develop methods that are needed to confidently detect, characterize, and quantify intentionally produced engineered nanomaterials (ENMs) released from food along the alimentary tract. This particular article offers an overview of the NRFA project, describing the project scope and goals, as well as the strategy by which the task group sought to achieve these goals. A condensed description of the general challenge of detecting ENMs in foods and a brief review of available and emerging methods for ENM detection is provided here, paying particular attention to the kind of information that might be desired from an analysis and the strengths and weaknesses of the various approaches that might be used to attain this information. The article concludes with an executive summary of the task group's broad findings related to the 3 topic areas, which are covered in more detail in 3 subsequent articles in this series. The end result is a thorough evaluation of the state of ENM measurement science specifically as it applies to oral uptake of ENMs from human dietary sources.