A patient is passing stones recurrently in urine for past few years. All are due to be restrlcted in diet except-

The inverse relationship between low dietary calcium intake and an increase in stone formation is likely due to a secondary increase in urinary oxalate. While urinary calcium levels decreased in both groups, urinary oxalate levels increased in men on the low calcium diet and decreased in men on the normal calcium diet Ref Harrison20th edition pg 277