Uricosuric effect of Roselle (Hibiscus sabdariffa) in kidney stone formers
The herb Roselle (Hibiscus sabdariffa) was investigated for its ability to reduce uric acid crystals in the urine (uricosuric effect). Nine subjects with no history of renal stones (non-renal stone, NS) and nine with a history of renal stones (RS) was used in this study. A cup of tea made from 1.5 g of dry Roselle calyces (the outside portion of the flower) was provided to subjects twice daily (morning and evening) for 15 days. A blood and two consecutive 24-hour urine samples were collected from each subject three times: (1) at baseline or the start of the study (control period); (2) on days 14 and 15 during the tea drinking period; and (3) 15 days after the tea drinking was stopped (washout period). Serum and 24-h urinary samples were analyzed for uric acid and other chemical compositions related to urinary stone risk factors. RESULTS:
In the RS group, both uric acid excretion and clearance were significantly increased. When the fractional excretion of uric acid was calculated, the values were clearly increased in both the NS and SF groups after the intake of tea and returned to baseline values in the washout period. These changes were more clearly observed when the data for each subject was presented individually. The study is published in the May 2008 issue of the Journal of Ethnopharmacology .