For many a generation, mothers and grandmothers alike have sworn by cranberry juice as a suitable home remedy for urinary tract infections (UTIs).
To understand the science behind this treatment option, Dr. Rose Khavari, assistant professor of urology at the Institute for Academic Medicine at Houston Methodist Hospital, joined “Take Care” for a conversation on UTIs and the effectiveness of cranberry juice and cranberry supplements.
A UTI is diagnosable, says Khavari, when the urine contains at least 100,000 bacteria per milliliter. And further, depending on the location, it will be classified as an upper or lower tract infection.
Upper UTIs, also known as pyelonephritis, are much less common than lower, and reside in the kidneys. And while lower UTIs are undoubtedly irritating, upper UTIs will cause harsher symptoms, such as chills or a fever. Lower UTIs, which occur in the bladder, are a much more frequent occurrence, and include symptoms like painful or frequent urination, incontinence, lower abdomen pain, and cloudy, sometimes bloody, urine.
So where do cranberries come into play? According to Khavari, cranberries are 90 percent water, along with a combination of citric acid, natural sugars, and the magic molecule, proanthocyanidins (PACs). This active ingredient is the key to cranberries’ reputation, and has shown promise in aiding lower UTIs, but not upper. In a lower urinary tract infection, bacteria (commonly E. coli) cling to the walls of the bladder and multiply. PACs prevent this clinging, thus stopping any further proliferation of bacteria.
However, despite the science behind PACs, “I wish we had stronger supportive evidence behind it,” says Khavari.
Because while PACs appear effective, she stresses the importance of the differentiation between cranberry juice and cranberry supplements. Due to the variability in amounts of the active ingredient in these cranberry products, it can be difficult to make sense of the findings in studies and apply them to patients.
Based on the research available, the generally accepted dosage of PACs necessary for results is thirty-six milligrams, twice a day. This comes out to roughly twenty ounces of cranberry juice per day, indefinitely, to prevent a UTI or two, which according to Khavari, is “just not feasible.” For this reason, Khavari does not put much stock in the effectiveness of plain cranberry juice as treatment for a lower UTI. From the high caloric content to the taste in general, one can expect to see a lot of drop-off in patient participation over time.
In terms of the effectiveness of cranberry supplements, however, the verdict is still out. In a recent study by the Yale School of Medicine, a sample of female nursing home residents, all sixty-five and older, took two thirty-six milliliter capsules of cranberry supplements daily for a year. When the results were collected, doctors did not find that there were fewer bacteria in the patients who took supplements versus the control group. In fact, the experimental group also did not experience any symptom relief, making the supplements seem fairly ineffective.
But this study was not perfect, Khavari explains. Because although it was a well-designed experiment, it used a very narrow subgroup. Considering the participants were all in nursing homes with a median age of 85, it would be unreliable to apply these results to an entire population.
It seems more evidence is necessary to determine whether cranberries and cranberry supplements are effective in treating lower UTIs. As always, talk to your doctor if you’re experiencing UTI symptoms, but if you’d like to try for yourself, incorporating cranberry supplements into your routine poses little risk.