A modified Caco-2 cell model system was developed for studying iron availability in mixtures of fresh and/or cooked foods subjected to a simulated gastrointestinal digestion. The effect of combining foods containing high levels of ascorbic acid with cooked eggs on ferritin expression in the cells was measured. There was no detectable increase in ferritin with eggs alone, indicating that none of the iron was available for uptake into the cells, but when mixed with orange juice or salad (lettuce, tomatoes, and red pepper) in ratios similar to those found in meals, there was a significant increase in ferritin concentration (p = 0.0012 and p = 9.2 x 10(-10), respectively); the enhancing effect of salad was greater than orange juice (p = 0.028). These results suggest that the iron in eggs will be more readily absorbed when consumed with foods high in ascorbic acid.