Uric acid. Molecular model of uric acid, a waste compound that is produced during the digestion of purine-rich foods such as meat and fish. Uric acid is excreted in urine, but a diet high in purine-rich food causes high uric acid blood levels. This can lead to gout (a type of metabolic arthritis) or kidney stones (mineral deposits in the kidneys). These conditions are caused by the accumulation of uric acid crystals in bodily tissues, hindering their function. Uric acid may also cause mini strokes, but conclusive evidence is yet to be found (as of 2007). Atoms are colour-coded: hydrogen (yellow), carbon (pale blue), nitrogen (dark blue) and oxygen (red).