The Role of Nutrition in the Prevention and Management of Urinary Tract Infections (UTIs)- A Review for Dietitians

Urinary Tract Infections (UTIs) are uncomfortable, painful and can be disruptive to daily life. 

Approximately 50–60% of women and persons assigned female at birth (AFAB) experience at least one UTI in their lifetime. 

This article explores whether nutrition interventions can be an effective strategy for the prevention and management of UTIs. 

Pathophysiology of UTIs

Urinary tract infections (UTIs) primarily result from the ascent of uropathogenic bacteria, particularly Escherichia coli (E. coli), from the periurethral region to the bladder. Once in the bladder, the bacteria adhere to the urothelial lining using Type 1 pili containing FimH adhesins. This adhesion initiates colonization, biofilm formation, and evasion of immune defenses. 

The bacteria may invade urothelial cells, forming intracellular bacterial communities, which can persist as reservoirs for recurrent infections. Host factors such as urine flow and immune responses play critical roles in mitigating bacterial establishment​.

Women and persons assigned female at birth (AFAB) are at higher risk of UTIs in part due to their shorter urethra and proximity of the urethra to the anus. Risk factors include:

• Sexual activity, especially with new partners

• Use of spermicides or diaphragms

• Pregnancy, due to hormonal and mechanical changes

• Postmenopausal estrogen deficiency, altering vaginal microbiota​

  
  

Symptoms of UTIs can include:

• Painful urination 

• Frequent urination 

• Cloud and foul smelling urine

• Blood in the urine

• Chills and/or low grade fever

• Flank or lower back pain 

• Pelvic pain 

• Fatigue

  
  

Can diet or supplements help prevent UTIs?

Cranberries 

Cranberries contain proanthocyanidins (PACs), which inhibit E. coli adhesion to the urothelium. A systematic review of 7 randomized control trials found that cranberry juice and supplements reduced the incidence of UTIs in women by up to 26%. However, the authors do note that risk of bias was high in 2 of the studies, and the sample sizes were generally small. 

A 2023 cochrane review including 50 studies with 8857 people also demonstrated a significant reduction in UTI recurrence. It is unclear if juice or tablets were more effective, however, the authors commented that adherence was more challenging with juice compared to tablets because of its taste.  Cranberry products did not reduce the risk of UTIs for older adults, in adults with neuromuscular bladder dysfunction and incomplete bladder emptying, or in pregnant women. 

Probiotics

Probiotics, particularly Lactobacillus species, restore and maintain a healthy vaginal microbiota, which acts as a barrier against uropathogens. While some studies suggest benefits, the findings are inconsistent. A meta-analysis of three randomized controlled trials (RCTs) with 284 participants found no significant effect of probiotics compared to placebo in reducing UTI recurrence.

D-Mannose

D-Mannose, a naturally occurring sugar, binds to FimH adhesin on E. coli, preventing bacterial attachment to the bladder wall. A randomized trial comparing D-mannose to antibiotics found comparable efficacy in reducing UTI recurrence. However, a 2024 placebo-controlled trial did not find significant benefits of D-mannose over placebo for recurrent UTIs in primary care settings​.

Fluid Intake

Higher fluid intake increases urinary flow, reducing bacterial colonization. Maintaining hydration as a simple yet effective preventive measure​.

Limitations of the Research

• Heterogeneity: Significant variability in intervention types, dosages, and study designs limits generalizability

• Sample Size: Many trials had small participant numbers, reducing statistical power.

• Bias and Funding: Many studies are funded by industry e.g. producers of cranberry jucie

• Long-term Outcomes: Limited evidence exists on the sustainability of benefits over prolonged periods​

Does cranberry juice prevent or cure UTIs?

While more research is needed, cranberry juice and tablets may be beneficial for preventing recurrent UTIs. The evidence for probiotics and D-mannose is currently lacking. 

It is important to note that dietary interventions or supplements do not cure existing UTIs. If an individual has symptoms of an existing UTI, they should reach out to their primary care providers or a pharmacist for assessment and treatment.

Individuals should seek medical attention if they have:

• Persistent symptoms after self-management

• Symptoms such as fever, flank pain, blood in the urine 

• Frequent recurrences (≥3 infections per year)

• High-risk groups, including pregnant individuals, older adults, and those with diabetes

What is the dose for cranberry juice and tablets to prevent UTIs? 

Preventive interventions like cranberry and encouraging fluid intake should begin in individuals with known risk factors or a history of recurrent UTIs before they experience symptoms. 

The challenge is that we do not know the exact dose of proanthocyanidins (PACs) in cranberry products that are effective since there is so much variability in the amounts tested in the research. 

Currently most sources recommend about 8 oz of pure cranberry juice without added sugar per day or 500 mg cranberry extract. However, more research is needed to confirm this. 

Recommendations for Dietitians:

1. Encourage adequate water intake to help increase urinary flow

2. Provide education on the lack of data on D-Mannose and probiotics as more robust studies are conducted

3. If an individual wishes to try cranberry products, recommend them as a tool for prevention rather than treatment. Communicate that more research is needed on the appropriate dose and frequency of cranberry products for the prevention of UTIs

4. Educate clients on when they should seek medical attention. Untreated UTIs put individuals at risk of serious complications in including kidney infection and damage