More evidence to suggest the health benefits of cranberry juice were revealed this week by researchers in Germany. Setting out to evaluate the influence of plum-, cranberry- and blackcurrant juice on urinary stone risk factors, the scientists obtained positive results.

Investigations were carried out on 12 healthy male subjects aged between 18 -38 years old. All subjects received a standardised diet formulated according to the dietary recommendations of the German Society of Nutrition. The subjects provided 24 h urine collections in a control, three loading phases. In each loading phase a neutral mineral water was substituted for 330 ml of the particular juice.

Results revealed that cranberry juice decreased the urinary pH, whereas the excretion of oxalic acid and the relative super-saturation for uric acid were increased. In contrast, blackcurrant juice increased the urinary pH, the excretion of citric acid and the excretion of oxalic acid. According to the scientists all changes were statistically significant. The plum juice had no significant effect on the urinary composition.

The scientists, based at the University of Bonn, concluded that blackcurrant juice could support the treatment and metaphylaxis of uric acid stone disease because of its alkalising effect. Since cranberry juice acidifies urine it could be useful in the treatment of brushite and struvite stones as well as urinary tract infection.

Full findings are published in the recent issue of the European Journal of Clinical Nutrition (2002) 56, 1020-1023. doi:10.1038/sj.ejcn.1601442.