Cranberry juice is a classic remedy for urinary tract infections—and is one of the home remedies that has been relatively well studied. However, the key point is often overlooked: cranberries are primarily effective as a preventive measure.
Prevention rather than treatment
Studies show that the effect is particularly evident in women with recurrent urinary tract infections. The number of new infections can decrease with regular consumption. According to a Cochrane review, the risk of recurrent infections is reduced by about 25–30% in women; the effect appears to be slightly stronger in children. Some groups, such as pregnant women and nursing home residents, did not benefit.
In cases of acute bladder infections, there is hardly any positive effect. Once the infection has taken hold, the mechanism simply comes too late—the bacteria have already attached themselves to the mucous membrane and are multiplying.
What’s Behind the Effect
According to studies, simply drinking more water alone can significantly reduce the number of recurrent urinary tract infections. However, the effect of cranberries is not about “flushing,” but rather the active compounds contained in the plant: proanthocyanidins (PACs), which make it difficult for bacteria to attach to the bladder lining. E. coli, the most common cause of urinary tract infections, relies on this adhesion. Without it, it becomes significantly harder for the bacteria to establish themselves in the urinary tract.
Juice, capsules, or extract—and how much, exactly?
And how and in what quantity is it best to take cranberry? There is no standard dosage recommendation. Studies often use about 36 mg of proanthocyanidins per day. It is not possible to give a general figure for how much juice is needed, as the proanthocyanidin content varies significantly depending on the product. When taking dietary supplements, you should pay attention to the information regarding PAC content.