The caco-2 cell bioassay for measurement of food iron bioavailability

Authors: Glahn, Raymond

Submitted to: The Journal of Visualized Experiments (JoVE)
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/1/2022
Publication Date: 4/28/2022
Citation: Glahn, R.P. 2022. The caco-2 cell bioassay for measurement of food iron bioavailability. The Journal of Visualized Experiments (JoVE). 182. Article e63859. https://doi.org/10.3791/63859.
DOI: https://doi.org/10.3791/63859

Interpretive Summary: Knowledge of iron (Fe) bioavailability is critical to the assessment of the nutritional quality of Fe in foods. Measurement of Fe bioavailability in animals or humans is limited by cost, throughput, and the caveats inherent to tracking the absorption of the Fe. Thus, there exists a critical need for an approach that is high-throughput and cost-effective, and not subject to the challenges of measurement in animals or humans. The Caco-2 cell bioassay was developed to satisfy this need. The Caco-2 cell bioassay for Fe bioavailability utilizes simulated gastric and intestinal digestion coupled with culture of a human intestinal epithelial cell line known as Caco-2. In Caco-2 cells, Fe uptake stimulates the intracellular formation of ferritin, an Fe storage protein easily measured. Ferritin forms in proportion to Fe uptake; thus, by measuring Caco-2 cell ferritin production, one can assess intestinal Fe uptake from simulated food digests into the enterocyte. Via this approach, the model replicates the key initial step that determines food Fe bioavailability. Since its inception in 1998, this model approach has been rigorously compared to factors known to influence human Fe bioavailability, and thus is thoroughly validated and accepted in the field of nutrition. This paper provides detailed methods and materials for this bioassay, and will eventually be linked to a video to assist users in replicating this bioassay in their research facility.

Technical Abstract: Knowledge of Fe bioavailability is critical to the assessment of the nutritional quality of Fe in foods. In vivo measurement of Fe bioavailability is limited by cost, throughput, and the caveats inherent to isotopic labeling of the food Fe. Thus, there exists a critical need for an approach that is high-throughput and cost-effective. The Caco-2 cell bioassay was developed to satisfy this need. The Caco-2 cell bioassay for Fe bioavailability utilizes simulated gastric and intestinal digestion coupled with culture of a human intestinal epithelial cell line known as Caco-2. In Caco-2 cells, Fe uptake stimulates the intracellular formation of ferritin, an Fe storage protein easily measured by enzyme-linked immunosorbent assay (ELISA). Ferritin forms in proportion to Fe uptake; thus, by measuring Caco-2 cell ferritin production, one can assess intestinal Fe uptake from simulated food digests into the enterocyte.