Effect of citrus-based products on urine profile: A systematic review and meta-analysis

Background. Urolithiasis is a disease with high recurrence rate, 30-50% within 5 years. The aim of the present study was to learn the effects of citrus-based products on the urine profile in healthy persons and people with urolithiasis compared to control diet and potassium citrate.  Methods. A systematic review was performed, which included interventional, prospective observational and retrospective studies, comparing citrus-based therapy with standard diet therapy, mineral water, or potassium citrate. A literature search was conducted using PUBMED, COCHRANE, and Google Scholar with "citrus or lemonade or orange or grapefruit or lime or juice" and "urolithiasis" as search terms. For statistical analysis, a fixed-effects model was conducted when p > 0.05, and random-effects model was conducted when p < 0.05.  Results. In total, 135 citations were found through database searching with 10 studies found to be consistent with our selection criteria. However, only 8 studies were included in quantitative analysis, due to data availability. The present study showed a higher increased in urine pH for citrus-based products (mean difference, 0.16; 95% CI 0.01-0.32) and urinary citrate (mean difference, 124.49; 95% CI 80.24-168.74) compared with a control group. However, no differences were found in urine volume, urinary calcium, urinary oxalate, and urinary uric acid. From subgroup analysis, we found that citrus-based products consistently increased urinary citrate level higher than controls in both healthy and urolithiasis populations. Furthermore, there was lower urinary calcium level among people with urolithiasis.  Conclusions. Citrus-based products could increase urinary citrate level significantly higher than control. These results should encourage further research to explore citrus-based products as a urolithiasis treatment.