A PILOT study has found no significant link between natural dietary intake of d-mannose or urinary acidity and the risk of recurrent urinary tract infections (RUTIs) among postmenopausal women, challenging assumptions about how diet might help prevent these common infections.
Researchers recruited 57 women aged 64 to 75 who had a history of RUTIs to explore whether dietary factors, including d-mannose consumption, and urinary pH levels might influence infection risk. The participants used urinalysis reagent strips four times a day over three days to measure urinary pH, while keeping detailed food diaries over the same period. Based on their urinary acidity, the women were divided into two groups: those with urine pH predominantly below 6 (more acidic) and those with pH predominantly above 6 (less acidic).
No Clear Dietary Differences Found in UTI-Prone Women
Analysis of the participants’ diets revealed no statistically significant difference in D-mannose intake between the two groups. D-mannose, a simple sugar found in some fruits and marketed as a supplement for UTI prevention, did not vary meaningfully with urinary pH. Similarly, other nutrient intakes showed no major distinctions tied to urine acidity.
However, foods containing D-mannose were found to be more nutrient-dense overall. Compared with non-D-mannose-containing foods, they had significantly higher amounts of protein, carbohydrates, fat, calcium, iron, and water (all p < 0.01). Small differences in fibre, sugar, and sodium intake were also noted between groups, though these were not considered clinically significant.
Interestingly, the study found that while naturally occurring d-mannose was present in participants’ diets, the quantities were generally lower than those found in commercial supplements. In a few cases, dietary intake approached supplemental doses, but this was the exception rather than the rule.
Next Steps in UTI Research
The authors caution that this was a small, single-institution study and emphasise that larger, controlled trials are needed to determine whether D-mannose supplementation or urinary acidity truly influence RUTI recurrence. For now, the findings suggest that, among postmenopausal women with prior UTIs, typical dietary patterns do not appear to provide sufficient D-mannose to mimic the effects of supplementation, or to affect urinary pH enough to alter infection risk.
Reference
Chavez JM et al. Comparison of D-mannose in foods with urine pH in post-menopausal women with recurrent urinary tract infections. Urology. 2025.
