Most research suggests that ingestion of cranberry juice may be useful in preventing urinary tract infections. This pilot study examines the effect of drinking moderate amounts of commercially available cranberry juice cocktail on urinary pH in older, institutionalized adults. The results of the study have implications for home care nurses who have similar patients in their case loads.

The purpose of this study was to quantitate the effect of cranberry juice ingestion on urinary acidification and calcium excretion, in a diet-controlled situation.

The influence of diet on aryl acid metabolism was determined in normal and azotemic subjects. Aryl acid content of serum and urine was estimated by fluorometry in relation to hippuric acid as a standard (FI-Hipp). Secretory activity, a reflection of the biological potency of aromatic acids in serum and urine, was determined by bioassay. The urinary excretion of FI-Hipp and secretory activity of five normal persons on an ad lib diet was 0.78 and 2.25 mM/day, respectively; similar values were observed in two subjects with chronic renal insufficiency. Subjects were fed prunes and cranberries, since these foods contain abundant quantities of hippurate precursors. Prunes 1.5 g/kg body weight, caused the urinary excretion of both FI-Hipp and secretory activity to increase about tenfold in normal and azotemic subjects. Prune feeding caused the serum levels of FI-Hipp and secretory activity to increase about threefold. Cranberries increased the renal excretion of FI-Hipp and secretory activity as did the ingestion of a beverage containing benzoate as a preservative. On the basis of these studies it is clear that diet is an important determinant of the load of aryl acids for urinary excretion; in patients with renal insufficiency the ingestion of foods containing precursors may cause serum level of biologically active aryl acids to increase strikingly.

Bacterial surface properties, such as electrostatic potential play an important role in the bacterial adhesion process, which is widely considered as the first step leading to infections. Cranberry juice and its compound A-type proanthocyanidins (PACs) were used to treat two isogenic E. coli strains and human uroepithelial cells and the zeta potentials were measured at several cranberry juice or PACs concentrations. P fimbriae were shown to be slightly positively charged, which helps bacteria adhere onto mammalian cells. PACs significantly decreased the bacterial zeta potentials from -15.6 ± 0.9 mV to -41.5 ± 0.7 mV, which increased the electrostatic repulsion forces to mammalian cells. Cranberry juice treatment did not change bacterial zeta potentials significantly, ranging from -14.9 ± 1.8 mV to -16.3 ± 0.8 mV. The abundance of other compounds in cranberry juice may have blocked the influence of PACs, considering the relatively small proportion of PACs in cranberry juice.

An extract from fresh cranberries was shown to decrease the strength of attachment of Escherichia coli to glass coverslips when incubated together for 2 h. Pre-conditioning of the surface prior to biofilm formation also significantly weakened the strength of attached cells.

BACKGROUND: The inhibition of Escherichia coli growth in the presence of Vaccinium macrocarpon has been extensively described; however, the mechanisms of this activity are not well characterized.

FINDINGS: Here, E. coli was grown in media spiked with cranberry juice. The growth rate and media pH were monitored over more than 300 generations. The pH of the growth media was found to decrease during cell growth. This result was unique to media spiked with cranberry juice and was not reproduced through the addition of sugars, proanthocyanidins, or metal chelators to growth media.

CONCLUSION: This study demonstrated that factors other than sugars or proanthocyanidins in cranberry juice result in acidification of the growth media. Further studies are necessary for a complete understanding of the antimicrobial activity of cranberry products.

An ethanolic extract of Cranberry exerted a significant antimicrobial effect on Saccharomyces bayanus and Pseudomonas fluorescens. The antimicrobial properties of cranberries were due to a number of factors. First, the low pH (2.6) inhibited many microorganisms per se, and its effect on the dissociation of benzoic acid made the inhibition more drastic. Secondly, after raising the pH to 5.2, cranberry juice still did not support the growth of S. bayanus. Growth did occur at pH 5.2 after 0.3% yeast nitrogen base was added. Thirdly, proanthocyanidins and flavonols were found to be the major microbial inhibitors other than benzoic acid. The results showed that proanthocyanidins provided 21.3% of the inhibition, the flavonols 18.5% and benzoic acid 15.6%.

Cranberry juice has developed a following as a simple, nonpharmacologic means to reduce or treat urinary tract infections, yet the scientific basis for such a claim has been lacking. A new study suggests that bacterial infections (bacteriuria) and associated influx of white blood cells into the urine (pyuria) can be reduced by nearly 50% in elderly women who drink 300 mL of cranberry juice cocktail each day over the course of a 6-month study. The results of this study suggest that consumption of cranberry juice is more effective in treating than preventing bacteriuria and pyuria. Along with earlier reports on the ability of cranberry juice to inhibit bacterial adherence to urinary epithelial cells in cell culture, this new work suggests that drinking cranberry juice each day may be clinically useful. Additional work must be conducted, however, to more completely define the efficacy of cranberry juice.

OBJECTIVES: To determine the safety, tolerability, maximal tolerated dose, and efficacy of a concentrated cranberry liquid blend, UTI-STAT with Proantinox, in female patients with a history of recurrent urinary tract infections (rUTIs).

METHODS: The study agent was administered orally at 15, 30, 45, 60, and 75 mL daily for 12 weeks to women with a history of 2.78 ± 0.73 rUTIs 6 months. Blood and urine samples were collected at baseline and weeks 4 and 12. The women took daily doses of the agent. The primary endpoints were the safety, tolerability, and maximal tolerated dose. The secondary endpoints were the efficacy with regard to rUTI and quality-of-life (QOL) symptoms.

RESULTS: A total of 28 subjects were included in the study. Of these 28 women, the data from 23 were analyzable. The average age was 46.5 ± 12.8 years. The maximal tolerated dose of UTI-STAT was 75 mL/d, and the recommended dose was set at 60 mL/d. The secondary endpoints demonstrated that only 2 (9.1%) of 23 reported a rUTI, a markedly better rate than the historical data. At 12 weeks, the reduction in worry about rUTIs and increased QOL with regard to the physical functioning domain and role limitations from physical health domain, as measured by the Medical Outcomes Study short-form 36-item questionnaire, were significant (P = .0097). A lower American Urological Association Symptom Index indicating greater QOL was also significant (P = .045).

CONCLUSIONS: The novel concentrated cranberry liquid blend showed a good safety profile and tolerability in both pre- and postmenopausal women with history of rUTIs. The secondary endpoints demonstrated its effectiveness in reducing the incidence of rUTI and increasing QOL. Given this evidence, supplementation might be beneficial in the prevention of rUTIs in this population.