Clinical, epidemiological and mechanistic studies support the role of cranberry (Vaccinium macrocarpon Ait.) in maintaining urinary tract health. Cranberry proanthocyanidins contain A-type linkages and have been associated with preventing adhesion of P-fimbriated uropathogenic Escherichia coli to uroepithelial cells. It is not known if the presence of the A-type linkage is a prerequisite for anti-adhesion activity. Other commercial sources of proanthocyanidins with all B-type linkages have not previously been screened for this activity. The goals of this study were to compare the in vitro anti-adhesion activity of A-linked proanthocyanidins from cranberry juice cocktail with the anti-adhesion activities of B-linked proanthocyanidins from commercial grape and apple juices, green tea and dark chocolate, and determine if anti-adhesion activity is detectable in human urine following consumption of single servings of each commercial food product. Structural heterogeneity and presence of the A-type linkage in cranberry proanthocyanidins was confirmed utilizing MALDI-TOF/MS and DI/ESI MS, as was the presence of all B-type linkages in the proanthocyanidins from the other commercial products. The isolated A-type proanthocyanidins from cranberry juice cocktail elicited in vitro anti-adhesion activity at 60 microg/ml, the B-type proanthocyanidins from grape exhibited minor activity at 1200 microg/ml, while other B-type proanthocyanidins were not active. Anti-adhesion activity in human urine was detected following cranberry juice cocktail consumption, but not after consumption of the non-cranberry food products. Results suggest that presence of the A-type linkage in cranberry proanthocyanidins may enhance both in vitro and urinary bacterial anti-adhesion activities and aid in maintaining urinary tract health.