Cranberry

Cranberry, Vaccinium macrocarpon, is known more as a colourful fruit than as a medicinal herb. But First Nations used the tart, red berry of this perennial for food and medicine, introducing it to early settlers as a treatment for scurvy, stomach ailments, urinary problems, and as a blood cleanser.

Reliable Preventive for Bladder Infections

Today the primary medicinal use for cranberry is to prevent recurring urinary tract infections. Initially it was believed that cranberry was effective because it acidifies the urine and makes it an inhospitable environment for bacteria to grow. However, recent well-documented studies have indicated that it is the condensed tannins or proanthocyanidins in ripe fruit that inhibit E. coli bacteria from adhering to the cells of the urinary tract wall. Cranberry also helps flush bacteria from the bladder into the urine, resulting in a lower rate of infection. The anti-adhesion effect may start within two hours and last up to 10 hours after pure cranberry juice is consumed, suggesting that one serving in the morning and another in the evening may provide more effective protection than only one serving a day. Cranberry juice cocktail, which typically contains only 27 to 33 percent cranberry juice, is not as effective as pure juice.

Because the tannins in cranberry are easily destroyed by stomach acid before they reach the needed site of action, concentrated cranberry extract may be more effective. A recent study published in the Canadian Journal of Urology compared the effects of cranberry tablets, pure cranberry juice, and placebo for prevention of urinary tract infections. In a one-year study of 150 women at high risk, the active tablets given provided a minimum of 30:1 cranberry extract. Results indicate that cranberry tablets are slightly more effective than pure juice and more cost effective for the prevention of urinary tract infections.

Battles Bacteria

New research indicates that the anti-adhesion properties of cranberry may also be effective against bacteria in other areas of the body. It may prevent the H. pylori bacteria that causes peptic ulcers from sticking to gastric mucous and stomach epithelium. A recent clinical trial using fresh and commercially prepared cranberry juices also showed a significant reduction in Streptococcus mutans, the bacteria that causes most dental cavities.

Ongoing research also suggests that the high levels of flavonoids in cranberry may naturally defend against atherosclerosis or clogging of the arteries by inhibiting low-density lipoprotein oxidation. Researchers at the University of Western Ontario are studying the potential anti-carcinogenic properties of cranberry and, while the laboratory results are preliminary, the compounds in cranberries show promise in lowering tumour development in mice that have been injected with human breast cancer cells.

Too Much of a Good Thing

Cranberries are considered safe for use with other medications and during pregnancy and lactation. However, some commercial cranberry juice cocktails contain high levels of sugar or artificial sweeteners and should not be consumed in large quantities by people with diabetes, hyperglycemia, or obesity. Drinking large amounts of cranberry juice may cause stomach upset and diarrhea.

Numerous published studies propose that the regular consumption of cranberry juice may protect against certain antibiotic resistant bacteria that can cause recurrent urinary tract infections. Prevention of these infections could potentially decrease antibiotic use and ultimately reduce further development of antibiotic resistance.