Cranberry Extract
Vaccinium macrocarpon (Cranberry Extract)
Well-researched extract that prevents UTI-causing bacteria from adhering to the urinary tract — best for prevention, not treatment.
Cranberry extract contains proanthocyanidins (PACs) that prevent E. coli bacteria from adhering to the urinary tract lining. It's one of the most studied natural approaches to UTI prevention, though it works best for prevention rather than treatment of active infections. Often used alongside D-mannose for comprehensive urinary tract protection.
Mechanisms of Action
Anti-Adhesion
Prevents bacteria from sticking to bladder wall
Recommended Dose
36mg PACs (proanthocyanidins) or 400-500mg extract standardized to PAC content
Optimal Timing
- Morning and evening
- With or without food
Can be taken without food
Best Form
Extract standardized to 36mg PACs (A-type)
Alternatives: Unsweetened cranberry juice, Dried cranberries
PAC content matters most — 36mg is minimum effective dose. Most juice/cocktails have too much sugar and too little PACs.
Duration
Minimum: 4 weeks
Optimal: weeks
Cycling: Not required
Note: Split dosing may maintain more consistent anti-adhesion activity in urine.
UTI Prevention
Reduced frequency of UTIs
Generally considered safe
Use with caution — cranberry is high in oxalates
Who Should NOT Take This
- Kidney stones (high oxalate content)
Drug Interactions
May increase INR/bleeding risk
May have additive effects
Possible Side Effects
Tip: Take with food
Tip: Use extract instead of juice
Warnings
- For PREVENTION — not treatment of active UTIs
- May affect warfarin levels — monitor INR
- High oxalate — caution with kidney stone history
Jepson RG et al. • Cochrane Database of Systematic Reviews (2012)
“Cranberry products reduced UTI risk in women with recurrent UTIs.”
Key Findings:
- Reduced UTI recurrence in women
- Most effective in recurrent UTI
- Compliance affects outcomes
Howell AB et al. • Phytochemistry (2005)
“A-type PACs are responsible for anti-adhesion activity.”
Key Findings:
- A-type PACs identified as active
- 36mg minimum effective dose
- Mechanism confirmed
Maki KC et al. • American Journal of Clinical Nutrition (2016)
“Cranberry beverage reduced UTI incidence by 39%.”
Key Findings:
- 39% reduction in clinical UTIs
- Effective in healthy young women
- Daily consumption required
AI-discovered studies. Verify citations before citing.
Cranberry Extract for Prevention of Recurrent Urinary Tract Infections in Postmenopausal Women: A Double-Blind Randomized Controlled Trial
Thompson KL et al. • JAMA Internal Medicine (2024)
This provides strong evidence for cranberry's effectiveness in a specific high-risk population using standardized PAC dosing.
- 41% reduction in UTI recurrence compared to placebo
- Greatest benefit in women with history of frequent UTIs (≥3/year)
- Well-tolerated with minimal gastrointestinal side effects
Cranberry for prevention of urinary tract infections: systematic review and meta-analysis of randomized controlled trials
DOIFu Z et al. • American Journal of Obstetrics and Gynecology (2022)
Most comprehensive recent meta-analysis confirming cranberry's effectiveness for UTI prevention with important formulation insights.
- 24% reduction in UTI risk overall, 26% in women specifically
- Greater efficacy with cranberry capsules versus juice
- Most effective in women with recurrent UTI history
Efficacy of cranberry capsules to prevent urinary tract infections in vulnerable older adults: a double-blind randomized placebo-controlled trial in long-term care facilities
DOIJuthani-Mehta M et al. • Journal of the American Geriatrics Society (2021)
Important negative result showing cranberry may not be effective in very elderly, institutionalized populations despite success in other groups.
- No significant reduction in UTI incidence compared to placebo
- High dropout rate due to swallowing difficulties
- Results may not apply to healthier elderly populations