RED GRAPE JUICE INHIBITS IRON BIOAVAILABILITY: APPLICATION OF AN IN VITRO DIGESTION/CACO-2 CELL MODEL

Authors: BOATO, FRANCESACA - CORNELL UNIVERSITY; WORTLEY, GARY - CORNELL UNIVERSITY; LIU, RUIHAI - CORNELL UNIVERSITY; Glahn, Raymond

Submitted to: Journal of Agricultural and Food Chemistry
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/11/2002
Publication Date: 11/15/2002
Citation: BOATO, F., WORTLEY, G.M., LIU, R., GLAHN, R.P. RED GRAPE JUICE INHIBITS IRON BIOAVAILABILITY: APPLICATION OF AN IN VITRO DIGESTION/CACO-2 CELL MODEL. JOURNAL OF AGRICULTURAL AND FOOD CHEMISTRY. 2002.

Interpretive Summary: Adequate bioavailable Fe intake is essential for optimal growth and intellectual development of infants and children. Fruit juices are nutritious and popular drinks, and are known to contain Fe uptake inhibitors (e.g. polyphenolic compounds) and a dominant promoter, ascorbic acid. We utilized a simulated digestion/cell culture model to compare the effects of apple, pear, white grape, red grape, prune, grapefruit and orange juice on iron bioavailability. In two series of experiments, juices from a local supermarket were combined with iron-chloride or a commercial iron-fortified infant cereal and subjected to simulated gastric and intestinal digestion. The pear, apple, grapefruit, orange and white grape juice significantly increased Fe bioavailability from FeCl3 and the elemental Fe of infant cereal. In contrast, the red grape juice and prune juice had profound inhibitory effects on iron bioavailability. These inhibitory effects were likely due to high levels of polyphenolic compounds that bind and thereby prevent absorption of soluble Fe. From a nutritional standpoint, the results suggest that individuals in need of optimal Fe absorption should avoid red grape and prune juice or at least vary the types of juices consumed. Alternatively, individuals seeking to limit Fe uptake (e.g. hemochromatitics and astronauts) may be able to utilize red grape or prune juice as effective inhibitors of Fe uptake. Consumers should be aware that the compounds that inhibit Fe availability, are also linked to anticancer benefits; thus a dietary balance of the above juices may be optimal. More research is needed to determine if these in vitro effects are prevalent in human subjects.

Technical Abstract: Adequate bioavailable Fe intake is essential for optimal growth and intellectual development of infants and children. Fruit juices are nutritious and popular drinks for infants and children, and are known to contain Fe uptake inhibitors (e.g. polyphenolic compounds) and a dominant promoter, ascorbic acid. Ascorbic acid is naturally present in fruit juices, and added as a fortificant to almost all juices found in supermarkets. Therefore, we utilized an in vitro digestion/Caco-2 cell culture model to compare the effects of apple, pear, white grape, red grape, prune, grapefruit and orange juice on iron bioavailability. In two series of experiments, juices from a local supermarket were combined with FeCl3 or commercial infant cereal fortified with elemental iron and subject to simulated gastric and intestinal digestion. Caco-2 cell ferritin formation in response to exposure to the digests served as the measure of Fe uptake. The pear, apple, grapefruit, orange and white grape juice significantly increased Fe bioavailability from FeCl3 and the elemental Fe of infant cereal. In contrast, the red grape juice and prune juice had profound inhibitory effects on iron bioavailability. These inhibitory effects were likely due to high levels of polyphenolic compounds that bind and thereby prevent absorption of soluble Fe. These inhibitory compounds appeared to counteract the promotional effects of ascorbic acid as they were in considerable molar excess relative to ascorbic acid and Fe in the digest. From a nutritional standpoint, the results suggest that individuals in need of optimal Fe absorption should avoid red grape and prune juice or at least vary the types of juices consumed. Alternatively, individuals seeking to limit Fe uptake (e.g. hemochromatitics and astronauts) may be able to utilize red grape or prune juice as effective inhibitors of Fe uptake. Consumers should be aware that the compounds that inhibit Fe availability, are also linked to anticancer benefits; thus a dietary balance of the above juices may be optimal. More research is needed to determine if these in vitro effects are prevalent in human subjects.