After a washout period , subjects drank 1.5 L natural low-mineral water daily ( control , n = 77 ) , 0.5 L Hpar and 1 L natural low-mineral water daily ( Hpar 0.5 group , n = 85 ) , or 1 L Hpar and 0.5 L natural low-mineral water daily ( Hpar 1 group , n = 82 ) for 4 weeks .