Researchers hypothesizes that cranberries work principally by preventing the adhesion of type 1 and p-fimbriae strains (particularly from E. coli) to the urothelium. Without adhesion, bacteria cannot infect the mucosal surface. In vitro, this adhesion is mediated by two components of cranberries that are fructose, which inhibits the adherence of type 1 fimbriae, and PAC, which inhibits the adherence of p-fimbriae. The binding of the proteinaceous bacterial fimbrial tips to mucosal surfaces on the uroepithelium occurs as a specific receptor-ligand association favored by hydrophobic interactions. One possible mechanism is that the cranberry compounds, acting as receptor analogs, competitively inhibit the adhesion of E. coli to host cells by binding to the fimbrial tips.

The in-vitro anti-adherence effect of cranberries is dose-dependent. Another mechanism of cranberry activity is the in-vitro reduction in the expression of p-fimbriae in E. coli by changing the conformation of surface molecules. In a recent study, pH-neutralized cranberry juice induced conformational changes in the surface macromolecules of pfimbriated E. coli by specifically decreasing the fimbrial length and density.

Control group: Untreated

Test group 1: Received encapsulated 250 mg of PS-WCP twice daily (Low dose of 500 mg/day cranberry).

Test group 2: Received encapsulated 500 mg of PS-WCP twice daily (High dose of 1000 mg/day cranberry).

• Hematological parameters: hemoglobin, WBC and differential count, ESR, platelet count
• Serum biochemical parameters: FBG, triglycerides, cholesterol, bilirubin, CKNAC, SGOT, SGPT, urea, creatinine
• Urine analysis: sugar, albumin, ketone bodies, pus cells, RBC
• Questionnaire-based assessment on patients’ perceived overall improvement of symptoms
• Presence of urinary E. Coli and other uropathogens

Visible benefits

• The statistical analyses showed that there was no significant changes observed in the hematological and serum biochemical parameters in the treatment groups at the end of the 90-day follow-up period, suggesting that cranberry product PSWCP was safe and nontoxic for human consumption.
• 18 participants out of 44 in the treatment groups reported that they had complete relief and remission from urological symptoms such as itching and burning sensation during micturition, and frequent urination. Subjects in both treatment groups reported significant improvement of symptoms starting from the 10-day evaluation as compared to the baseline, whereas subjects in the untreated control group did not show any improvement in their symptoms.
• Both treatment groups also exhibited significant reduction of E. coli load (low dose, p<0.01; high dose p<0.0001; at a statistical significance level of 95%) after 10 days of treatment. E. coli was reduced at highly significant level (p<0.0001), and at a moderately significant (p=0.0151) level in the high dose and low dose treated groups, respectively.

Pilot study (To study acute effect)

Control group: Received placebo powder with similar color and taste to cranberry powder which contains a blend of water, maltodextrin, citric acid, artificial cranberry flavor (Lorann oils), fructose, red color, and grape shade.

Test group: Received 9 g cranberry powder containing 525 mg of total polyphenols, of which 374 mg were PACs.

Main study (To study chronic effect)

Control group: Received daily placebo powder with similar color and taste to cranberry powder which contains a blend of water, maltodextrin, citric acid, artificial cranberry flavor (Lorann oils), fructose, red color, and grape shade.

Test group: Received 9 g cranberry powder daily containing 525 mg of total polyphenols, of which 374 mg were PACs.

Visible benefits

Pilot study

Cranberry powder increased FMD at 2h and 4h by 1% as compared to control. The response did not difference between 2h and 4h.

Main study

A one-month consumption of whole cranberry powder led to a significant improvement in FMD, which was by 1.1%, as compared to the control. Similar significant improvements were observed at 2 h after the first cranberry intervention on day 1 but that there were no further improvements at 1 month and 2 h after consumption of the last cranberry powder. There was no significant time × intervention interaction, suggesting that the effect of cranberry did not differ between the time points and was independent of baseline FMD.

Control group: Consumed 240 mL of cranberry beverage consisting of water, milled whole cranberries, natural flavor, sucralose twice daily.

Test group: Consumed 240 mL of placebo beverage consisting of water, sucrose, xanthan gum, malic acid, fumaric acid, natural food color, natural flavor, and sucralose tiwce daily.

• GI tolerance (cramping, distension/bloating, flatulence)
• Fecal microbial composition

Visible benefits

• The combined incidents of moderate and severe flatulence were lower after participants consumed the cranberry as compared to the placebo group.
• Clostridium perfringens (pathogenic bacteria) was present only in the fecal samples of placebo group whereas Coriobacteriaceae (beneficial bacteria) was found abundantly in the fecal sample of cranberry group.

• The cranberry prebiotic components, including oligosaccharides and polyphenols may contribute to the increase in the relative abundance of Coriobacteriaceae. Coriobacteriaceae carries out important functions, such as the conversion of bile salts and steroids, activation of dietary polyphenols, and are key in the production of menaquinone-6 homologs of vitamin K. Furthermore, Coriobacteriaceae has been identified as potential biomarkers that link exercise with health improvement and are correlated with the levels of 15 metabolites that are markers of improved health outcomes.
• Cranberry extract inhibits the growth of Clostridium perfringens due to the activity of its active compounds such as tannin and oligosaccharides. Clostridium perfringens is a gram-positive spore-forming anaerobic bacterium that can cause the major intestinal disease.
• The fact that cranberry extract can reduce the incidence of flatulence is associated with its beneficial inhibition of the growth of Clostridium perfringens, which is a strong hydrogen sulfide-producing bacterium.

Effects of caries

• In oral diseases like caries and periodontitis, cranberries have shown therapeutic potential owing to their anti-adhesive and other anti-microbial properties.
• The polyphenolic fraction of the fruit is reported to suppress the formation of biofilms and acid production by cariogenic streptococci.
• In one study, cranberry fraction demonstrated the deactivation of enzymes glucosyltranferase and fructosyltranferase. These enzymes, essential to the formation of glucan and fructan, helped the adhesion of streptococci to the tooth surface, thereby inhibiting plaque formation.

Effects on periodontal bacteria and host mechanisms

• Cranberries prevent the adhesion of Gingivalis to various proteins including type I collagen, hence decreasing the bacterial coaggregation in periodontal diseases.
• Cranberries are reported to restrain the proteolytic activity of the red complex specifically the gingipain activity of gingivalis, trypsin-like activity of Tanerella forsythia and chemotrypsin-like activity of T. Denticola. Therefore, it is suggested that this fruit has the potential to limit the pathogen multiplication by restricting their growth resources from amino acids, peptides and also inhibit the tissue destruction mediated by bacterial proteinases.
• Cranberry components may inhibit the NF-κB and MMP-3, hence regulating aggressive periodontitis’s fibroblast inflammatory responses. (Antiinflammation)