The most important being Calcium. It binds with minerals which must be eliminated through the Kidneys. In large or small quantities with improper hydration this can lead to Kidney Stones and Kidney Damage. This is found in high concentration is peas, beans and cereals. This chemical also binds minerals as well as Proteins.
Purines are well known in humans as being a contributing factor in Gout.
Russian tortoises fed large amounts can develop Kidney Disease.