Targeted Natural Interventions
Cranberries contain substances that may be able to treat or prevent UTIs. Cranberry juice and powders made from cranberry extract have been used for decades to prevent or treat UTIs. Originally, it was hypothesized that one of the components in cranberry – quinic acid – increased the levels of a natural antibacterial agent in the urine, known as hippuric acid. However, it is not clear if there is a significant increase in hippuric acid levels in the urine after cranberry consumption (Jepson 2007, 2012).
Evidence suggests that substances known as proanthocyanidins, which are found in cranberries, may interfere with the adhesion of bacteria (particularly E. coli) to the walls of the urinary tract (Jepson 2007, 2012; McMurdo 2005). By preventing E. coli from binding to the urinary tract cells, proanthocyanidins can keep bacteria from fully colonizing and invading the urinary tract. One of the advantages of using cranberry juice or related products is that cranberries are relatively inexpensive, natural, and should not contribute to the growing problem of antibiotic resistance (McMurdo 2005).
One study found that both cranberry juice and cranberry tablets were effective at reducing urinary tract infections (compared to placebo) in women who developed at least one UTI per year. This study also found that cranberry tablets were a more cost-effective option compared to cranberry juice (Stothers 2002). Another study found that consuming cranberry juice three times per day produced a trend towards reducing the incidence of UTIs during pregnancy (Wing 2008). Yet another study compared cranberry extract to low-dose trimethoprim (a commonly used antibiotic) for prevention of recurrent UTIs in older women. This study found that regular use of trimethoprim was only slightly better than 500 mg of cranberry extract daily for preventing the recurrence of UTIs. It also found that women taking trimethoprim were more likely to withdraw from the study due to side effects (McMurdo 2009).
Although there are many studies that have examined the potential benefits of cranberry for UTIs, a recent comprehensive review concluded that the benefits of consuming cranberry juice for UTIs were minimal. However, many of the studies included in this review used sugar-laden cranberry juice cocktails; the high sugar content and the fact that many of these beverages are blends of different juices (reducing the proanthocyanidin content) may also obscure the benefits of cranberries (Jepson 2012).
D-mannose is a sugar that can be found in, among other things, cranberries. One of the interesting aspects of D-mannose is that it is able to bind to the cells that line the urinary tract (Hudson 2006) and to prevent bacteria, such as E. coli, from adhering to the lining of the urinary tract (Hudson 2006; Schaeffer 1980).
Much like cranberries, blueberries also contain compounds that can inhibit the adhesion of E. coli to the cells that line the urinary tract (Ofek 1991). In addition, both blueberries and cranberries contain compounds that are able to help prevent large aggregates of bacteria from forming (Weiss 2002). The clinical effect of blueberries on UTIs has yet to be thoroughly investigated.
Probiotics – beneficial bacteria that reside in the gut and positively impact the health of their host – are a promising natural treatment for UTIs. There are many possible ways that probiotics may prevent UTIs: they may compete with other bacteria for resources, secrete natural antibacterial chemicals (called bacteriocin), and prevent pathogenic bacteria from adhering to the urinary tract (Darouiche 2012).
Bacteria in the Lactobacillus family, normally found in the female vagina, are thought to prevent UTI (Darouiche 2012). Taking antibiotics or using spermicidal agents can kill off these Lactobacilli, which can then increase the risk of UTI (Reid 2001). In addition, recurrent UTIs are often associated with decreased levels of Lactobacillus bacteria and increased colonization with E. coli (Stapleton 2011). As a result, supplementing the vaginal flora with probiotic Lactobacilli may represent a viable technique for preventing UTIs (Reid 2001; Stapleton 2011; Kwok 2006). In particular, there is evidence that the Lactobacillus rhamnosus GR-1 and Lactobacillus reuterii RC-14 strains are clinically effective (Reid 2006).
Lactobacillus bacteria also may prevent UTIs by stimulating the immune system and producing substances that kill infectious bacteria, such as hydrogen peroxide and lactic acid (Darouiche 2012). A study comparing Lactobacillus bacteria to regular doses of trimethoprim-sulfamethoxazole (an antibiotic combination) found that the antibiotics were only slightly more effective than the probiotic treatment for uncomplicated UTI; however, probiotics were more effective in complicated cases, which was likely due to the presence of baseline antibiotic resistance rates in these cases. The authors also point out that probiotics had the advantage of not increasing the risk of antibiotic-resistant microorganisms (Beerepoote 2012).
Berberine, a chemical known as a plant alkaloid, has historically been used in Chinese and Ayurvedic medicine. It can be found in many plants, including goldenseal, Orgeon grape, coptis, barberry, and turmeric (Head 2008). Berberine has natural antibacterial properties and is effective at inhibiting the growth of many opportunistic pathogens, including E. coli (Cernakova 2002). Some studies have found that berberine prevents E. coli from adhering to cells that line the urinary tract, thus providing a possible mechanism of action for its UTI-preventative properties (Sun 1988). One study suggested that berberine may represent a new target for the development of pharmaceuticals (Domadia 2008). Berberine may not be safe for pregnant women, however, because it can induce uterine contractions and may cause jaundice in newborns (Head 2008).
Hibiscus is a family of plants that has traditionally been used to treat many different infections, including UTIs. Hibiscus plants contain many compounds that have antibacterial, antifungal, and antioxidant properties (Maganha 2010). One compound in particular, gossypetin, has been shown to have antibacterial activity against common UTI-causing bacteria, including E. coli and Pseudomonoas aeurginosa (Mounnissamy 2002). In a double-blind, placebo-controlled clinical trial, 61 women with a history of frequent UTIs were randomly assigned to one of 3 groups receiving a daily dose of 200 mg of hibiscus extract standardized to 90% polyphenols, 200 mg of hibiscus extract standardized to 60% polyphenols, or placebo. Compared to the control group, women taking the hibiscus concentrations experienced 77% fewer incidence of UTIs, as well as overall improvement in urinary comfort (Allaert 2009).
Vitamin C, also known as ascorbic acid, is one of the most commonly used vitamin supplements and it has a variety of effects on the human body. One potential benefit is that it may acidify the urine, which helps inhibit the growth of infectious bacteria in the urinary tract (Carlsson 2001). This acidification may also convert bacterial nitrites into nitric oxide, which is toxic to bacteria (Hudson 2006). In addition, vitamin C is important for the function of the immune system (Hudson 2006). Studies have found that taking 100 mg of vitamin C daily during pregnancy can reduce the incidence of UTIs (Ochoa-Brust 2007).
General Support for Healthy Bladder Function
Pumpkin seed extract. Urinary urgency and/or frequency are often associated with UTI. To this end, for those afflicted by UTIs, especially chronic UTI sufferers, taking steps to improve bladder tone and support healthy voiding patterns may be beneficial.
Although not studied specifically in the context of UTI, pumpkin seed extract has been shown to support bladder function and combat the symptoms associated with an overactive bladder. In an animal study, rats supplemented with pumpkin seed extract exhibited significantly improved bladder function and decreased urinary frequency (Hata 2005). In a human study involving 39 postmenopausal women, 6 weeks of supplementation with pumpkin seed extract plus soybean germ extract lead to significant decreases in daytime and nighttime urination (Sogabe 2001). In a similar study among 45 men, this same combination extract lead to reduced nighttime urination and improved sleep satisfaction after 6 weeks of supplementation (Terado 2004).