Oxalates are natural compounds found in foods – especially plant-based foods – where they serve the useful purpose of protecting the plant from being eaten by bugs because of their bitter taste. Not only are oxalates present in plants and foods, the body manufactures oxalates from other substances – including vitamin C. Oxalates are hard to completely eliminate from the diet; but they can cause problems for people who eat too many of them.
What are Oxalates?: Are They Harmful to Health?
The majority of kidney stones are made up of calcium oxalate; but it’s not clear whether lowering dietary oxalate actually reduces the risk of kidney stones – since only about twenty percent of oxalate comes from dietary sources with the rest being produced by the body. Still, most experts recommend that people with a history of kidney stones limit oxalates in their diet.
Another problem with oxalates is that some people don’t metabolism them well. In poor oxalate metabolizers, oxalates have an “irritant” effect on the body and may play a role in the pain people with conditions such as fibromyalgia experience – although there have been few studies confirming this. Oxalate binds with calcium creating calcium oxalate which deposits in tissues – leading to inflammation and pain.
Oxalates can also reduce the absorption of iron and other minerals by forming a complex with them. Iron supplements should never be taken with meals with foods high in oxalates.
Although the role of oxalates isn’t completely understood, too much oxalate in the body isn’t beneficial – particularly for people who have kidney stones or who don’t metabolism it well.
Can You Avoid Oxalates?
It’s almost impossible to eat an oxalate-free diet since it’s present in so many foods. Some foods with high oxalate levels include chocolate, leafy vegetables, black tea, beets, rhubarb, and beans. Vitamin C can be converted to oxalate which means people who have a history of kidney stones or inflammatory diseases shouldn’t take large doses of supplemental vitamin C. Cooking plant foods lowers oxalate levels, but only by about ten percent.
The Bottom Line?
People who suffer from inflammatory diseases or have a history of kidney stones should limit oxalates – although following a low oxalate diet can be a challenge. Complete lists of foods that are high in oxalate can be found online.