Mention the word cranberry to most people and they will cite one of Delia Smith’s popular cranberry recipes! Cranberries have long been used in the USA and Europe as an ingredient in cooking as well as a juice cocktail. Enthusiastic chefs however are not the only group who have shown an interest in these purple coloured berries. For many years researchers have focused on the use of cranberry for the management of chronic cystitis or urinary tract infection (UTIs). The term UTI is often used to describe unresolved or persistent bladder infections or to describe three or more bouts of bladder infections occurring in the course of one year.
Conventional Medicine
Conventional medicine for treating UTIs relies on antibiotics to kill off the primary bacteria causing UTIs – Escherichia coli (E.Coli) – but often these prove unsuccessful and lead to other health problems such as thrush and candida. These harmful bacteria often attach themselves to the epithelial linings of the gut and bladder where they cause pain, a burning sensation on passing urine and increased frequency of urination. Of the women treated for a UTI 20% will suffer a recurrence. Relapses like these are thought to result from unresolved infections and usually the treatment involves stronger, more powerful antibiotics with the risk that they become less effective over time. However, cranberry may offer some people a much gentler way to tackle the problem.
Active properties in Cranberry
At first it was thought that cranberry had an acidifying action on the urine thus making it an inhospitable environment for the bacteria responsible for UTIs, which prefer an alkaline pH. As far back as 1914, Blatherwick reported that cranberries are particularly rich in benzoic acid which is excreted as hippuric acid in the urine. Studies from the 1920s right through to the 1970s continued to suggest that acidification of the urine was the mechanism through which cranberry juice was able to prevent the growth of bacteria. However, other studies seemed to conflict with this hypothesis.
Now, more recently, a researcher by the name of Dr A.E. Sabota of Youngstown State University, USA demonstrated that cranberry juice and the urine produced by the cranberry beverage actually reduce the ability of these harmful bacteria to adhere to the bladder wall by around 80%.
Bacteria need to attach themselves to cells in the bladder to survive but when cranberry compounds are present the bacteria appear to mistake certain constituents in cranberry for bladder cells and they attach themselves to these constituents instead of the bladder wall. Once attached, the bacteria are in effect flushed out along with the urine, thus preventing the problem before it starts. Zafriri et al identified two compounds in cranberry juice that seemed to prevent bacteria adhering. One was fructose (commonly found in many fruit juices), the other a compound not found in grapefruit, orange, guava, mango or pineapple juices – but isolated in cranberry and blueberry juices.
Despite such findings, no controlled, randomised clinical trial had been performed until the 1990s.
Cranberry Trial
One of the most recent studies looking at the effect of cranberry juice on clinical urinary tract infections was carried out by Avron et al using 153 elderly women with an average age of 78 years. The women were randomly assigned to consume 300ml per day of a standard cranberry drink or a specially prepared synthetic placebo (ie. dummy) drink that was indistinguishable in taste, appearance and vitamin C content, but lacked cranberry content.
Urine samples were collected at the start of the study and then at one month intervals throughout the six month study. These were analysed for bacterial content and antibiotic sensitivity. The women assigned the cranberry drink were found to be 42% less likely to develop bacterial infection in their urine and those who did develop infection were 27% less likely to remain infected than those receiving the placebo.
These findings suggest that cranberry juice reduces the frequency of bacteria in the urine in older women. This is important, for high bacteria levels in the urine of elderly people make them susceptible not only to UTIs, but also to kidney infections.
Since Sabota’s work on cranberry, researchers at the Weizmann Institute in Israel have demonstrated cranberry’s ability to prevent adhesion of these pathogenic bacteria. They have identified fruit sugars (and a protein-based compound yet to be discovered) as the anti-adherence factor.
Cranberry Therapy
Although medical science has been aware of the potential usefulness of cranberries for some time, their use in therapy has been limited. The main reason for this is the volume of cranberry juice a person would need to drink (approximately 16 six-ounce glasses or 96 ounces a day) in order to consume enough of its valuable properties. Cranberry has by nature a rather bitter taste and many of the commercially available drinks are loaded with sugar and calories.
Nowadays it is possible to buy cranberry in powdered form so that it is easy to mix into water or fruit juices without any of the unnecessary additives. Be sure to choose a product in which the important properties of the berries have been further concentrated. Cranberry concentrate is particularly useful during pregnancy, at a time when women are often more susceptible to bladder infections. The therapeutic potential of cranberry in the long term management and prevention of UTIs is substantial and offers sufferers a real (safe) alternative to the prospect of antibiotics.
Low Calcium Status – look to cola?
A significant association was found between low calcium status and an intake of at least 1.5 litres per week of soft drinks containing phosphoric acid. This was highlighted in a case control study of 57 children (18 months – 14 years). Two thirds of these children with serum calcium levels <8.8mg/dl drank more than 1.5 litres each week of cola etc., compared with 28% of the control group.
In both groups combined, there was a significant negative correlation between serum calcium and the quantity of phosphoric acid containing soft drinks consumed each week. Among the 17 children followed up, serum calcium levels rose from 8.7 to 9.4 mg/dl and serum phosphorus levels fell from 5.7 to 4.7 mg/dl after soft drinks were discontinued for 30 days.
Comment:
Low serum calcium levels can be clinically significant, leading to problems such as muscle spasm, seizures and cardiovascular disease. This study suggests that phosphoric acid, found primarily in cola-type drinks, is an important cause of low calcium status in children. Of course, this is unlikely to be limited to children.
Reference:
Mazariegos – Ramos E, et al.
Consumption of soft drinks with phosphoric acid as a risk factor for the development of hypoglycaemia in children: a case-control study. J. Pediatr. 1995 7 126: 940-942
