It used to be that when you mentioned “cranberries,” people thought of turkeys and their taste buds. Today, they are as likely to think of their bladders because just about everyone has heard stories about how cranberry juice is supposed to prevent, or even treat, urinary tract infections. Does it? How would one find out? Well, researchers at Yale University designed a pretty clever experiment. They collected urine from three volunteers and then gave them 4 ounces of cranberry juice to drink. Four to six hours later they again collected urine, after which they repeated the experiment with 8 ounces of cranberry juice. The urine samples were then incubated with E. coli bacteria, the kind that normally are responsible for urinary tract infections. Separately, the scientists cultured cells taken from the lining of the human bladder and then mixed the cells with the urine samples. Lo and behold, the bacteria did not stick as effectively to the cells when the urine samples came from women who had consumed cranberry juice. Furthermore, the more juice consumed, the less the bacteria adhered to the cells. Although the specific ingredients in the juice responsible for this effect have not been conclusively identified, speculation is that substances known as trimeric procyanidins may be responsible.
These procyanidins may do more than prevent urinary tract infections. They may even have a role in preventing the recurrence and acquisition of infection with the herpes simplex type 2 virus, the nasty one that causes genital herpes. A group at Kaohsiung Medical University in Taiwan has shown that at least in the test tube, proanthocyanidin A-1, isolated from cranberries, suppresses the activity of the virus. The researchers suggest daily consumption of cranberry products to reduce the risk of acquiring such a herpes infection although they are unable to comment on amounts needed. And if you want more cranberry benefits, a study carried out at the University of Western Ontario showed that both cranberry juice and cranberry solids were able to slow down the multiplication of tumour cells in mice that had been injected with human breast tumour cells in their mammary glands.
Now for the downside. People susceptible to oxalate type of kidney stones may see an increased risk of stone formation because cranberries are rich in oxalates. But this is not a problem for the vast majority of people. Then there is another issue, a possible interaction between cranberry juice and coumadin, a common “blood thinner” taken by people who have had a stroke or have certain heart problems. Cranberries contain flavonoids which may inhibit enzymes that are used to break down certain medications. There have been a handful of reports of people on coumadin developing bleeding disorders after consuming cranberry juice, but there is yet no proof of cause and effect. Just to be on the safe side, it seems a good idea for anyone on coumadin to limit the amount of cranberry juice they consume. This of course does not apply to the general population who can happily drink the juice and possibly reap the anti-cancer and anti-infection benefits.
