Time for tea
Reviewed by Arun K Sharma

Kidney stone disease can be related to genetic, biochemical, and dietary factors. Much has been said about the link between tea and coffee consumption and risks of urinary stone formation. This is a systematic review using the PRISM statement with keywords including caffeine, coffee, black tea, green tea and kidney stones. Large studies reported risk reduction for stone disease in daily consumption of coffee and decaf coffee. In other studies, tea consumption was also shown to be protective. Despite the lithogenic role of caffeine, data in these studies suggest that coffee may paradoxically have a protective effect. Possible mechanisms include the diuretic effect of caffeine and the effect of adenosine receptors on the kidneys. Coffee plants are also a rich source of citric acid and citrate plays a strong role in stone prevention. The protective effect of green tea is likely to be due to polyphenol compounds called catechins which have antioxidant properties. There is a lack of standardisation on type of tea and method of preparation (e.g. addition of sugar and milk). Strong tea has been hypothesised to have a protective effect. This article will be of great interest to colleagues and patients alike in everyday practice.

Tea and coffee consumption and the risk of urinary stones – a systematic review of the epidemiological data.
Barghouthy Y, Corrales M, Doizi S, et al.
WORLD JOURNAL OF UROLOGY
2021;39(8):2895-901.