We investigated the importance of the large intestine on the bioavailability of anthocyanins from bilberries in humans with/without a colon. Low bioavailability of anthocyanins in plasma and urine was observed in the frame of this study. Anthocyanins reached the circulation mainly as glucuronides. Analysis of ileal effluents (at end of small intestine) demonstrated that 30% of ingested anthocyanins were stable during 8h passage through the upper intestine. Only 20% degradants were formed and mostly intact anthocyanins were absorbed from the small intestine. Higher amounts of degradants than anthocyanins reached the circulation after bilberry extract consumption in both groups of subjects. Comparison of the bioavailability of anthocyanins in healthy subjects versus ileostomists revealed substantially higher amounts of anthocyanins and degradants in the plasma/urine of subjects with an intact gut. The results suggested that the colon is a significant site for absorption of bioactive components such as anthocyanins and their degradation products.

Oxidative cell damage has been linked to the pathogenesis of numerous diseases such as atherosclerosis, type 2 diabetes, and cancer. The consumption of foods rich in polyphenols (eg anthocyanins) has been shown to exert preventive effects against such diseases. We investigated biological effects of anthocyanin-rich fruit juice in a 9-week, placebo-controlled intervention study with 57 healthy male volunteers. The study design encompassed an initial 1 week of wash-out, followed by 8 weeks of intervention period with anthocyanin-rich fruit juice or placebo. The anthocyanin-rich fruit juice demonstrated DNA-protective and antioxidant effects; however, the placebo beverage, rich in vitamin C, showed similar effects based on the tested biomarkers. A significant reduction in background and total DNA strand breaks was observed in both groups within 24 h as well as after 8 weeks of intervention. Only anthocyanin-rich fruit juice consumption provided a significant reduction in body fat and an increase in fat-free mass. The activity of superoxide dismutase (SOD) was significantly elevated after consumption of anthocyanin-rich fruit juice. Both groups showed decreased levels of LDL and total cholesterol (TC) within the first week of the intervention. Similar results in both groups could be explained by the relatively high vitamin C contents of both beverages (> 500 mg/L), which may have masked the effects of anthocyanins and other antioxidants in the studied juice. Taken together, anthocyanin-rich fruit juice as well as the placebo drink, both of which had high vitamin C content, can improve DNA integrity and might influence lipid metabolism in humans.

Anthocyanins are flavonoids that have been suggested to provide beneficial health effects. The biological activity of anthocyanins is influenced by their pharmacokinetic properties, but anthocyanins are associated with limited bioavailability in humans. In the presented study, we investigated how the encapsulation of bilberry extract (BE), a source of anthocyanins, with either whey protein or citrus pectin influences the bioavailability and intestinal accessibility of anthocyanins in humans. We performed an intervention study that analyzed anthocyanins and their degradation products in the urine, plasma, and ileal effluent of healthy volunteers and ileostomists (subjects without an intact colon). We were able to show, that whey protein encapsulation modulated short-term bioavailability and that citrus pectin encapsulation increased intestinal accessibility during passage through the small intestine and modulated the formation of the degradation product phloroglucinol aldehyde (PGAL) in human plasma.