Henry A. Lee1 and Dominic King1
(1)
Division of Surgery, Department of Surgery and Cancer, Imperial College London, London, UK
Henry A. Lee
Email: h.lee@imperial.ac.uk
Abstract
The objective of this chapter is to consider widely held popular beliefs surrounding UTIs and to see whether they stand up when scrutinized by medical research.
A great deal has been written on the subject of cranberry juice and its role in the treatment and prevention of UTIs. Cranberry juice can help prevent recurrent UTIs in women, but there is no evidence that it is effective in treating UTIs. Cranberry products work by inhibiting pathogenic adherence to the uroepithelium and probably not through acidification of the urine as was previously thought. Uva ursi (bearberry) can be used to treat UTIs affecting the lower tract, but should not be used for long-term prophylaxis as prolonged exposure to metabolites may be carcinogenic.
There is some weak evidence to suggest that probiotics and some vitamins (e.g., vitamin C) can help prevent UTIs. In addition to this, there is an association between frequency of sexual intercourse and UTIs, but not between number of partners and UTIs. Bubble bath probably does not increase the risk of UTIs, whereas condom use and contraceptive diaphragm use are associated with higher rates of UTI, although this should not discourage the use of safe sex.
Keywords
Urinary tract infectionComplementary therapyCranberry juiceProbioticsVitaminsSexual intercourseContraception
What Complementary Therapies Can Be Used in the Management of UTIs?
In the last decade, there has been widespread and increasing interest from Western populations in complementary therapies (also known as alternative therapy or medicine, natural remedies or therapy, or traditional therapy). Such therapies are used for many conditions, but there is a more widespread acceptance of their use for UTIs. The most popular, and most formally investigated, is cranberry juice or cranberry products [1]. Numerous other botanicals, such as berberine [2], blueberry [3], and uva ursi (bearberry) [4], have also been investigated, as have naturally occurring nutrients, such as vitamin C [5] and D–mannose [6], as well as probiotics [7, 8]. Nearly all complementary therapies used in relation to UTIs are for infections of the lower rather than upper urinary tract.
Can Cranberry Juice or Products Be Used to Treat UTIs?
Popular urban myths and “old wives” tales abound regarding the use of cranberry juice in the treatment of UTIs. A number of recent and methodologically robust systematic reviews have concluded that there is no evidence to suggest that cranberry juice, or cranberry products, are effective at treating UTIs [9–11].
Cranberry bush with fruit partially submerged
Can Cranberry Juice or Products Be Used to Prevent UTIs?
A Cochrane review and meta-analysis of the use of cranberry products in the prevention of UTIs concluded that over a 12-month period, daily use significantly reduced the incidence of UTIs [9]. The authors commented that the evidence was strongest for women with recurrent UTIs. There is mixed evidence to support the use of cranberry products in elderly populations [12]. There is no evidence to suggest that cranberry products are of benefit for preventing symptomatic UTIs in individuals with long-term urinary catheters [13].
There are many different cranberry product formulations and the recommended dose varies, depending upon the brand and concentration. The usual dose for UTI prevention is 250–500 ml daily and unsweetened juice is preferable [14]. Capsules that contain concentrated cranberry juice are a popular alternative and are usually taken two to three times a day for prevention [14]. It should be noted that although the popular conception of a glass of cranberry juice a day to prevent UTIs is an easy form of therapy to follow, the evidence would suggest otherwise. Compliance rates of less than 80 % are not uncommon, and in one study 63 % of participants dropped out [15], suggesting that cranberry products may not be acceptable for long-term use.
How Do Cranberry Products Prevent UTIs?
Cranberries (Vaccinium macrocarpon) have been used to treat and prevent UTIs for centuries as part of different folk remedies. There are two main mechanisms through which cranberry products are thought to prevent UTIs, acidification of urine and inhibition of bacterial adherence to the urothelium.
The acidification theory is a straightforward one and suggests that the quinic acid in cranberry juice causes large amounts of hippuric acid to be secreted in the urine [16]. The lowered pH of the urine creates an inhospitable environment for uropathogens. Doubt has been cast over this theory, however [1], as only short-lived reductions in urinary pH have been seen in more recent studies where participants have ingested usual amounts of cranberry products [17, 18]. A different explanation is that the ingestion of these products prevents pathogenic bacteria from adhering to the lining of the urinary tract. Cranberry products have been shown to prevent pathogenic adherence to the urothelium through interfering with fimbrial binding to epithelial cells [19]. Several different fruit juices (including guava, mango, grapefruit, and blueberry) have been shown to inhibit bacterial adherence related to type 1 fimbrial expression (mannose sensitive), whereas only cranberry juice and blueberry juice have been shown to reduce adherence related to type P fimbrial expression [3, 20].
Do Cranberry Products Interact with Other Medications?
Cranberry products are generally very safe. The main issue surrounding their use has been a possible interaction with warfarin. Based on 12 reports of possible interactions with warfarin [21], the British Committee on Safety of Medicines and the Medicines and Healthcare Products Regulatory Agency issued advice that patients taking cranberry juice with warfarin should have their international normalized ratio (INR) monitored closely [22]. A subsequent systematic review has, however, shown no available data to support cranberry juice as the agent responsible for the INR elevations [23].
What Other Botanicals Can Help Prevent UTIs?
Blueberries (Vaccinium myrtillus), also known as bilberries, are thought to help prevent UTIs through a similar mechanism as cranberries [3], although blueberry juice is less acidic. There is certainly less evidence from clinical practice to support blueberry use, although this may, in part at least, be due to the fact that cranberry juice has been more widely available for a longer period than blueberry juice. Given that blueberries have gained “superfood” status in the popular press [24, 25], it is likely that more work will be forthcoming in this area in the near future. Guidelines on the effective dose or volume of blueberry product to prevent UTIs are difficult to obtain and vary, depending upon the brand and concentration purchased.
Blueberry (Wikipedia)
Berberine is a plant isoquinoline alkaloid that is yellow in color and bitter to the taste. It has been used in Ayurvedic and Chinese medicine for many centuries [26] and can be found in many plants, e.g., oregon grape (Mahonia aquifolium), goldthread (Coptis chinensis), and goldenseal (Hydrastis canadensis) [27]. It has principally been used for treatment of gastrointestinal infections such as Giardia lambliaand E. coli, although its use in relation to UTIs has been reported [27]. Its mechanism of action is thought to be due to direct bacteriostatic action through inhibiting cell division [28] and prevention of bacterial adhesion [29]. Berberine, or remedies containing this supplement, should not be taken during pregnancy due to the risk of inducing uterine contractions.
Goldenseal (Wikipedia)
Uva ursi (Arctostaphylos uva ursi), also known as bearberry, is a shrub native to mountainous regions of North America. The leaves of the shrub contain the glycoside arbutoside, which, when ingested, is absorbed as hydroquinone and, after hepatic glucuronidation, is renally excreted [4]. The hydroquinone is spontaneously released from hydroquinone glucuronide as long as the urine is sufficiently alkali (pH > 7) and has direct antibacterial effects. Unlike cranberry products, uva ursi is used for the treatment and not prevention of UTIs and has federal licensing for treatment of UTIs in Germany [14]. It should not be taken for long-term prophylaxis, however, as there is some concern that prolonged use may be carcinogenic. The recommended dose in Germany is 3 g leaf extracted in 150 ml water by either hot or cold infusion up to four times daily, providing 400–840 mg arbutoside [14].
Bearberry (Wikipedia)
Juniper (Juniperus communis) is a tree that is found predominantly in temperate European regions and is another botanical with antimicrobial activity that has been used to treat UTIs [14]. The use of juniper tea for UTIs is a common folk remedy across Europe, and its activity is believed to be through the action of antimicrobial terpenoids that may have additional diuretic activity.
Cones and leaves from the juniper tree (Wikipedia)
Additional botanicals that have also been used in the treatment of UTIs include buchu (Barosma betulina), marshmallow root (Althea officinalis), horsetail (Equisetum arvense), dandelion leaf (Taraxacum officinale), and corn silk (Zea mays). These complementary therapies may be as efficacious as those named above, but have not yet been as extensively investigated.
How Effective Are Probiotics at Treating and Preventing UTIs?
Probiotics are another complementary therapy that has gained popularity in recent years, with supermarkets and health-food stores carrying an increasing range of such products. Probiotics are described by the WHO as “live microorganisms, which when administered in adequate amounts confer a health benefit to the host” [30].
Probiotics famously owe their origins to an observation made by Russian Nobel Laureate Ilya Mechnikov, who attributed the long life and good health of Bulgarian peasants to their consumption of large quantities of yogurt that contained lactic acid bacteria [31].
Compared to their application in gastrointestinal conditions, the use of probiotics in the treatment of UTIs has been the focus of much less medical research [7, 8], although there have been several trials investigating their use in preventing recurrent UTIs [32–35]. The results of these, however, have not consistently upheld the use of probiotics, and in fact, only one trial reported a significant reduction in recurrent episodes [32]. These studies have almost exclusively been undertaken in young women with recurrent UTIs, and there is little evidence to demonstrate effectiveness in other groups.
Can Vitamins Be Used to Treat UTIs?
There is some evidence to support the use of vitamins, but no body of work proves that they can replace more conventional therapies in treating infections. Vitamin C, for example, is a complementary therapy that is widely believed to be beneficial in treating UTIs [36], yet despite its popularity on the high street for this purpose, the evidence to support a direct effect of vitamin C in treating UTIs is not overwhelming. Vitamin C has been shown in small studies to be useful in helping to prevent urinary tract infections in pregnant women [5] and has been shown to help protect against UTI in a case-controlled study of college-aged women [37]. Vitamin A has also received some attention in respect to the prevention of UTIs, although mainly in pediatric populations. There is limited evidence to support its use in conjunction with initial antimicrobial therapy [38], although results are far from conclusive [39].
Potassium and sodium citrate salts have been used in the alkalinizing of urine and are a commonly used complementary therapy that has been widely adopted by the medical community. Their effect is brought through raising the pH of the urine and, in doing so, inhibiting microbial pathogenesis. They are particularly efficacious in treating symptomatic dysuria [40] and help potentiate the effects of certain botanicals such as uva ursi. D–Mannose is another nutrient that is a popular complementary therapy for treating UTIs [27, 41]. Pathogenic E. coli bind to the urinary tract via a specific mannose-sensitive receptor mechanism [42, 43], and by increasing urinary mannose through dietary supplementation, bacterial adherence and subsequent pathogenesis can be reduced. There is, however, no clinical trial data demonstrating the efficacy or otherwise of D–mannose in humans.
Can Acupuncture Help Prevent UTIs?
Acupuncture is suggested as an effective means of preventing UTIs by alternative therapy stores and in the self-help literature. Unfortunately, this seems to amount to little more than unproven enthusiasm. Other than numerous individual testimonials, a literature search found only one trial into acupuncture to prevent UTIs [44], and this followed on from work by the same authors [45]. This study showed that participants in the acupuncture group developed fewer UTIs than controls, but has been criticized in terms of study design and for the conclusions made on the basis of the results [46].
Acupuncture needles being inserted into a patient’s skin (Wikipedia)
Does Having Sex Cause UTIs?
The link between heterosexual vaginal intercourse and UTIs is a popular association held by the general public and has given rise to the term “honeymoon cystitis” or “honeymoon bladder” [47]. The link between primary UTI and intercourse was suggested in a study that demonstrated that young nuns have a lower level of bacteriuria than other populations [48] and has been subsequently substantiated by cross-sectional case-control studies and prospective population-based cohort studies [49–52].
For women who suffer from recurrent UTIs, sexual intercourse has also been shown to be a strong predictor of developing a symptomatic infection [53], and other works on college populations have shown that sexual intercourse increased the risk of recurrent UTI in women, with both a different and the same uropathogen as the first UTI [54].
Is There a Link Between Number of Sexual Partners and UTIs?
Generally speaking, UTIs are not regarded as sexually transmitted infections, and as such there is no link between the number of sexual partners and UTIs [37, 51, 55]. There is, however, an association between the frequency of intercourse and UTIs [52]. Unmarried young women having vaginal intercourse more than seven times per week have been shown to have a nine times increased risk of UTI, compared to those who did not have sexual intercourse during this period, with investigators demonstrating a dose-response relation between recent sexual intercourse and the risk of UTI [49].
Does Drinking Lots of Water Help Treat a UTI?
The belief that “flushing out” infections is one that is firmly fixed in the consciousness of the general public and of healthcare professionals alike. The evidence to support this, however, is far from clear and is contradictory to a degree [56, 57]. Studies in the 1960s based on reproductive rates of bacterial pathogens, prior to knowledge that bacteria adherence was integral to virulence, demonstrated that flow alone was not sufficient to flush out bacteria when voided volumes were small [58].
It is certainly the case that individuals with UTI should avoid dehydration to ensure optimal immune function and that any concomitant antimicrobial treatment is effective. There is evidence that many women with recurrent UTIs are helped by a fluid intake or more than 2 l/day [59]. Perhaps the most well-balanced advice is from Kunin, who suggests that “instruction to patients to drink ample fluids and void frequently appears to be justifiable, except when the patient is being treated for infection with agents that need to be concentrated in the urine” [60].
Can Drinking Carbonated or Caffeinated Drinks Cause UTIs?
Internet forums for UTIs and health self-help websites repeatedly advocate avoiding carbonated and caffeinated drinks (such as cola, tea, and coffee), but to say that they cause UTIs is untrue. These beverages may, however, mimic or exacerbate symptoms of a UTI and have been associated with increased rates of UTIs in some populations.
Caffeine is believed to increase detrusor pressure [61] and also acts as a mild diuretic, so it may exacerbate the lower urinary tract symptoms associated with a UTI. Regular consumption of cola drinks and tea has been shown in some studies to be strongly associated with UTIs, as have coffee and other carbonated drinks to a lesser extent [36], although another work has not demonstrated these links [50]. Preliminary results from a more recent study suggest that tea, coffee, and cola are all strongly associated with developing UTIs [62].
Are There Any Other Popular Misconceptions About Lifestyle Factors and UTIs?
One popular myth states that the wearing of tight-fitting clothes can predispose to UTIs. Not much formal work has been done into this area, but one study of college-aged women showed that wearing tight jeans, as compared to loose/very loose jeans, was strongly associated with first UTI, and moderately associated with second UTI [36]. Wearing cotton underwear is commonly regarded as helpful in preventing UTI, although there is no evidence to support this widely held belief, and one study showed an association between first UTI and wearing cotton underwear [36]. There was a slight association between bubble baths and UTIs in one study, but no other evidence to convincingly support or refute the well-known claim that bubble baths predispose to UTIs. However, there is good evidence that contraceptive diaphragms are associated with UTIs [50, 63], as is condom use [52, 64].
Key Points
· Cranberry juice can help prevent recurrent UTIs in women, but there is no evidence that it is effective in treating UTIs.
· Cranberry products work by inhibiting pathogenic adherence to the uroepithelium and probably not through acidification of the urine as was previously thought.
· Uva ursi can be used to treat UTIs affecting the lower tract, but should not be used for long-term prophylaxis as prolonged exposure to metabolites may be carcinogenic.
· There is some weak evidence to suggest that probiotics and some vitamins can help prevent UTIs.
· There is an association between frequency of sexual intercourse and UTIs, but not between number of partners and UTIs.
· Bubble baths probably do not increase the risk of UTIs, whereas condom use and contraceptive diaphragm use are associated with higher rates of UTI.
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