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UTI and cranberry
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In one pass Most urinary infections start with Escherichia coli from the gut. Educational content, not medical advice — consult a clinician.
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Chapter 1
Bacteria have to stick first
菌先要粘住
Most urinary infections start with Escherichia coli from the gut. Urine wash-out clears what cannot stick. What stays uses fimbriae — P-fimbriae recognise sugar receptors on the epithelium. Only then can it multiply and inflame.
So the first cut of this island is not killing the bug. It is stopping it sticking. The kidney island covers filtration and concentrating. This island covers the bladder and urethral epithelium. Red flags (fever, loin tenderness, pregnancy, a first episode in a man) are medical care, not more of one juice.
So the first cut of this island is not killing the bug. It is stopping it sticking. The kidney island covers filtration and concentrating. This island covers the bladder and urethral epithelium. Red flags (fever, loin tenderness, pregnancy, a first episode in a man) are medical care, not more of one juice.
Chapter 2
PAC is a decoy, not the acid
PAC 是诱饵, 不是酸
Howell 1998 writes the cranberry fraction that stops P-fimbriae as condensed tannins (proanthocyanidins, PAC), not how acidic the fruit is. Anti-adherence was detectable in vitro at 10 to 50 micrograms per millilitre; other Vaccinium berries shared the activity, most other produce did not. It is a letter, not a trial.
Read it as occupying the sugar-binding site on the fimbria so the bacterium cannot stick. Writing it as acidifying urine to kill bugs reads a decoy as a disinfectant.
Read it as occupying the sugar-binding site on the fimbria so the bacterium cannot stick. Writing it as acidifying urine to kill bugs reads a decoy as a disinfectant.
Chapter 3
Whom Cochrane actually covers
Cochrane 覆盖了谁
Williams 2023 pools juice, tablets and capsules against symptomatic, culture-verified UTIs. Moderate certainty: overall RR 0.70 (0.58-0.84; 26 studies, 6211 people). Split by indication, the signal sits in women with recurrent UTIs (RR 0.74), children (RR 0.46), and people susceptible after a bladder-related intervention (RR 0.47). Institutionalised elderly, pregnant women, and neuromuscular bladders that do not empty: current evidence does not support it.
The numbers are the shape of who may benefit, not how much of the bottle on the shelf to drink. The review also does not pin an optimal PAC dose.
The numbers are the shape of who may benefit, not how much of the bottle on the shelf to drink. The review also does not pin an optimal PAC dose.
Chapter 4
Mannose is a different decoy
甘露糖是另一只诱饵
Type-1 fimbriae recognise mannose. D-mannose is sold as a soluble decoy: the bacterium binds the sugar instead of the epithelium. Kranjcec 2014: after treating an acute episode, 308 women with recurrent UTIs, 2 g powder daily versus nitrofurantoin versus none for six months; recurrence 14.6% / 20.4% / 60.8%. RR versus no prophylaxis 0.239, not different from the antibiotic arm. It is one trial; the authors asked for replication.
The two decoys recognise two fimbriae. Do not merge them into one magic juice. Febrile pyelonephritis is not answered here — that is medical care.
The two decoys recognise two fimbriae. Do not merge them into one magic juice. Febrile pyelonephritis is not answered here — that is medical care.
References · 3
- Howell, A. B., Vorsa, N., Der Marderosian, A., & Foo, L. Y. (1998). Inhibition of the adherence of P-fimbriated Escherichia coli to uroepithelial-cell surfaces by proanthocyanidin extracts from cranberries. New England Journal of Medicine, 339(15), 1085-1086. Correspondence: the anti-adherence activity is from condensed tannins (proanthocyanidins), not the acidity of the fruit. Detectable at 10-50 micrograms per millilitre in vitro. A letter, not a clinical trial. 10.1056/NEJM199810083391516
- Williams, G., Stothart, C. I., Hahn, D., Stephens, J. H., Craig, J. C., & Hodson, E. M. (2023). Cranberries for preventing urinary tract infections. Cochrane Database of Systematic Reviews, 2023(11), CD001321. Moderate-certainty evidence: cranberry products reduced symptomatic, culture-verified UTIs (RR 0.70, 95% CI 0.58-0.84; 26 studies, 6211 participants). Benefit in women with recurrent UTIs (RR 0.74), children (RR 0.46), and people susceptible after an intervention (RR 0.47). No support in institutionalised elderly, pregnant women, or neuromuscular bladder dysfunction. 10.1002/14651858.CD001321.pub7
- Kranjcec, B., Papes, D., & Altarac, S. (2014). D-mannose powder for prophylaxis of recurrent urinary tract infections in women: a randomized clinical trial. World Journal of Urology, 32(1), 79-84. After acute cystitis treatment, 308 women: 2 g D-mannose daily vs 50 mg nitrofurantoin vs no prophylaxis for 6 months. Recurrent UTI 14.6% vs 20.4% vs 60.8%. D-mannose RR 0.239 vs no prophylaxis; not different from nitrofurantoin. Single trial; authors asked for replication. 10.1007/s00345-013-1091-6