Abstract
Little is known about the effects of coffee that are not related to the presence of caffeine. The aim of the study was to analyse changes in kidney function and nucleotide metabolism related to high intake of decaffeinated coffee. Mice consumed decaffeinated coffee extract for two weeks. Activities of AMP deaminase, ecto5′-nucleotidase, adenosine deaminase, purine nucleoside phosphorylase were measured in kidney cortex and medulla by analysis of conversion of substrates into products using HPLC. Concentration of nucleotides in kidney cortex, kidney medulla and serum were estimated by HPLC. Activity of ecto5′-nucleotidase increased from 0.032 ± 0.006 to 0.049 ± 0.014 nmol/mg tissue/min in kidney cortex of mice administered high-dose decaffeinated coffee (HDC) together with increase in cortex adenosine concentration and decrease in plasma creatinine concentration. HDC leads to increased activity of ecto5′-nucleotidase in kidney cortex that translates to increase in concentration of adenosine. Surprisingly this caused improved kidney excretion function.
Highlights
It is estimated that more than 59% of adults in the United States drink coffee beverages and in other developed countries [1]
Coffee espresso was prepared from 7 g decaffeinated coffee powder in 25 ml of water by high-pressure coffee machine. 0.33 ml of caffeine coffee and 0.33 ml decaffeinated coffee were diluted to 5 ml of water for daily dose, respectively, of Caffeine (Caff) and low-dose decaffeinated coffee (LDC) for mice. 3.3 ml of decaffeinated coffee extract was diluted to 5 ml of water which was the approximate daily high dose for mice—high-dose decaffeinated coffee (HDC)
Concentration of adenosine (Ado) increased twofold in kidney cortex mice drinking high-dose decaffeinated coffee (HDC) and increased but it was less in Caff and LDC group
Summary
It is estimated that more than 59% of adults in the United States drink coffee beverages and in other developed countries [1]. While consumption of coffee is prevalent, approximately 15% of the U.S population has stopped drinking coffee altogether, citing concerns about health, coffee reduction has been a strategy to prevent urinary tract symptoms such as bladder pain syndrome [1]. Caffeine consumption in the 200–300 mg range increases urinary calcium levels in both younger and older individuals, the predominance of data suggests that caffeine has a greater impact on calcium metabolism and bone in older people [3]. While caffeine intake may increase urine calcium excretion, caffeine-containing beverages have been associated with a lower risk of nephrolithiasis. Caffeine intake is associated with a lower risk of incident kidney stones [4]
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