Materia Medica

Vaccinium macrocarpon Ait. (cranberry, trailing swamp cranberry), V. oxycoccos L. (small cranberry), V. erythrocarpum Michx. (Southern mountain cranberry), V. vitis (lowbush cranberry), V. edule (highbush cranberry).    Ericaceae.  The common name is cranberry.

Cranberries have long been popular as a food item, making jams, preserves and relishes, particularly popular at Thanksgiving.  Eastern European cultures have used cranberries in the treatment of cancers and to reduce fever.  It was as early as the mid-1800s that German physicians observed that the excretion of hippuric acid increased after eating cranberries.  The effectiveness of cranberry juice for urinary tract infections spread anecdotally for many years despite the allegations of scientists that the acidification was not significant enough to be an effective treatment.

Members of Vaccinium grow in areas ranging from damp bogs to mountain forests.  Many species are cultivated in natural or artificial bogs throughout the United States, but especially in Massachusetts and Washington. Other plants of the Vaccinium species include blueberry, bilberry and lingonberry.

The ripe berry is the part used.  The whole berry is available fresh, frozen,canned and juiced at any grocery store.   Cranberries are also available in capsule form.

Cranberry juice to combat urinary infections is a common folk remedy that has been used for centuries.  It was commonly assumed that cranberries acidified the urine and this accounted for the effects of treating and preventing infections.   There is an increase of hippuric acid in the urine, thought to be a result of the benzoic acid in the berries.   Studies have had mixed results in testing these conclusions.  Some studies found the pH levels to be inconsistent and transitory.^[i]  Other studies have found there is a lowering of the pH from an increase of the excretion of hippuric acid.^[ii]  This effect is not reliable enough to be considered effective.  There is evidence that cranberry does reduce bacteriuria and pyuria in urine in older woman and could be used as a preventive to urinary infections.^[iii]

It has been proposed for some time that there was another mechanism at work that accounted for the favorable results of cranberry juice with urinary tract infections.  It was found that there is significant inhibition of bacterial adherence, particularly of E. coli to the uroepithelial cells.^[iv]  The fructose in the cranberries was originally thought to be the cause of this inhibition of adherence.  The most recent discovery is that it is the proanthocyanidins that are the responsible agents for preventing uropathogenic phenotypes of P-fimbriated E. coli from adhering to the urinary tract.^[v] 

Cranberry juice is finding use as a urinary deodorant for incontinent patients.  It appears to change the pH sufficiently to retard the degradation of urine by E. coli, thereby slowing the creation of the pungent ammoniacal odor.^[vi]  It may also decrease the occurrence of urinary stones.^[vii]  Cranberry juice also shows some antifungal^[viii] and antiviral^[ix] activity.

The juice contains anthocyanin dyes, catechin, triterpenoids, proanthocyanidins, about 10% carbohydrates and a small amount of protein.  The main organic acids are citric, malic and quinic, and lesser amounts of benzoic and glucuronic acids.  The glycoside leptosine and other related compounds have been found, as well as a small amount of alkaloids.

Three to six ounces of juice, twice a day is recommended for prevention of urinary infection, with up to 32 ounces a day for an active infection.  Six capsules are equivalent to three ounces of the juice.  Large amounts, more than 3 or 4 L per day of the juice can cause diarrhea and other gastrointestinal symptoms.