Oxalates are sharp crystals that occur naturally in humans, animals and plants (berries, green beans, almonds, soy, cocoa). Children with autism have shown a 3 fold increase in plasma oxalate levels compared to their peers, which means that they may not be able to metabolize oxalates properly. This can result in painful urination and kidney stones. High level oxalates can be absorbed into the tissue of the body, resulting in inflammation and pain. Oxalates also bind to necessary minerals like calcium, magnesium and zinc causing a mineral deficiency in the body. This can deplete the body’s antioxidant levels, which reduces the function of the immune system and exposes the individual to greater chances of illness and the inability to detoxify.
More information on Oxalates can be found on the following websites:
The River to Recovery 
Thanks for this article. So many people are unaware of the many problems a diet of high oxalate foods can cause. I suffered terrible, debilitating joint pain for years until I learned about oxalates in foods. Oxalate crystals began to form in my joints causing pain and inflammation. On a low oxalate diet I found amazing results. It was a year of learning how to cook low oxalate meals and to finally be free of that pain for good. I have written and published 2 cookbooks to help others see that a low oxalate diet isn’t as daunting as it seems at first. You can find Low Oxalate Fresh and Fast Cookbook and Real Food Real Results on Amazon.