IS ANTIOXIDANT ACTIVITY OF WHEY PROTEIN MAINTAINED DURING UPPER GASTRIC TRANSIT

Abstract

Supplementation of food with antioxidants may help to reduce oxidative stress in the body. Whey proteins are widely used in various foods for their nutritional, health promoting and functional value. One of the health promoting attributes of whey is its antioxidant activity. The objective of this study was to determine whether commercial whey protein isolate (WPI) maintains its antioxidant activity during upper gut transit and to identify the main whey protein responsible for this bioactivity. Individual whey proteins (β-lactoglobulin, α-lactalbumin, bovine serum albumin and lactoferrin) and WPI were subjected to static in vitro gastrointestinal digestion (SGID). Antioxidant activity of the proteins, pre and post SGID, were measured and compared using various antioxidant assays (ORAC, ABTS and FRAP). To determine whether WPI could boost intracellular antioxidant levels in intestinal epithelial cells, CaCo2 cells were exposed to SGID whey and intracellular glutathione levels quantified. Whey proteins, particularly α-lactalbumin (21.0% ABTS inhibition), exhibit antioxidant activities which are further enhanced during gut transit (37.3% ABTS inhibition, P 0.05). In conclusion, whey proteins exhibit antioxidant activities but their ability to boost intracellular antioxidant status of cells remains to be determined.