Beneficial effects of cranberries on intestinal health
Inflammatory bowel disease is a group of inflammatory symptoms affecting the gastrointestinal tract. Prebiotics are selectively fermentable ingredients that stimulate the growth and/or activity of beneficial gut bacteria. We hypothesize that cranberries can exert prebiotic effects on Lactobacillus plantarum (Lp) and Bifidobacterium longum subsp. infantis (Bi). In experiment 1, Lp and HT-29 colonocytes were co-incubated overnight (10:1) in the presence of cranberry extract (CE) at 0, 0.01, or 0.1 mg proanthocyanidin (PAC)/mL and then stress-induced with 10 ng/mL TNF-a; for 6h. Combination of Lp and CE downregulated (P<0.05) NFkB, COX-2 and IL-1b gene expression in a dose-dependent manner compared to Lp alone. Lp+0.01 mg PAC/mL decreased (P<0.05) IL-1b, IL-2, IL-4, IL-6 and IL-8, suggesting an enhanced anti-inflammatory effect. Post TNF-a stress, the Lp+0.1 mg PAC/mL treatment upregulated (P<0.05) SOD activity and inhibited COX-2 and IL-8, suggesting antioxidant and anti-inflammatory activity. In experiment 2, we developed a novel synbiotic mouse diet containing Bi. Colony counts were used to quantify viable Bi throughout the storage period at -80ºC, 4ºC or after 24h at 23ºC. The initial Bi concentration (1.03×10^9 cfu/d) was maintained for at least 5d when stored at -80ºC. The addition of 3% whole cranberry powder (WCP) and pectin to the mouse diet had no effect on Bi viability. In a 14-d feeding study, the BALB/c mice (6wk old; n=48) consumed 3.73g/d, providing an average intake of 1.48×10^9 cfu Bi/mouse/d. Experiment 3 assessed the effects of feeding WCP on dextran sulfate sodium (DSS)-induced colitis (3% for 7d) in female BALB/c mice (6wk old; n=48). Mice were fed the AIN-93G basal diet (DSS control) or the diet supplemented with 1×10^9 cfu Bi alone, Bi+1% WCP, or Bi+3% WCP for 21d. Supplementation with Bi alone suppressed (P<0.05) disease activity for 19d compared to DSS control and was further delayed until d 20 after WCP was added, indicating delayed colitis onset. The addition of 1% WCP increased (P<0.05) ZO-1, occludin, claudin-3, and claudin-4. At 3%, WCP increased (P<0.05) claudin-4 and decreased claudin-1, crypt damage, and PGE2. Overall, WCP delayed colitis onset, alleviated inflammation, improved the gut barrier function and promoted anti-cancer effects.