OXALATES

WHAT ARE OXALATES?

Oxalates cannot be seen, tasted, or smelled yet people consume them almost every day. A healthy human body has the ability to manage mild levels of oxalates in foods. Some are degraded by the oxalate-degrading anaerobic bacterium that colonizes the large intestines and some are bound by minerals during digestion and are excreted.

If the body isn’t able to process oxalates in this manner they have a negative impact on your health. Oxalates, also called oxalic acid, are naturally occurring substances found in varying degrees primarily in plant foods such as vegetables, fruits, grains, legumes, spices, herbs, and almost all nuts and seeds. These molecules are present in the leaves, roots, stems, fruits and seeds. Plants produce this toxic substance to provide a defense against insects and grazing animals. These needle-like crystals tear up the teeth of insects or animals which try to eat them.

Most fruits and vegetables contain measurable amounts of oxalates. Some, such as rhubarb, spinach, and raspberries have especially high levels. Oxalates in foods are classified as antinutrients meaning they interfere with the absorption of vitamins, minerals, and other nutrients. They even get in the way of digestive enzymes, which are vital for proper digestion and absorption of nutrients. There are two types of oxalates, soluble and insoluble but the exact form of oxalate doesn’t matter if one has an oxalate issue. Soluble simply means the oxalate is able to dissolve in water and insoluble means it won’t. For instance the oxalates in tea leaves are soluble because they can be boiled out of the leaf and into the beverage. Oxalate foods lists rarely distinguish if a food consists of soluble or insoluble oxalates.

Generally, a healthy individual will not experience ill effects from small amounts of oxalates in the diet. Most people are able to safely metabolize a certain amount of oxalates in foods due to specific bacteria in the digestive tract called Oxalobacter formigenes. Problems occur when gastrointestinal microbiota has been reduced or depleted and ingested oxalates are not metabolized. Another safe way the body eliminates oxalates is the binding of it with minerals in the gastrointestinal tract. Minerals such as magnesium and calcium can bind oxalates allowing them to pass in the stool. While this inhibits absorption of these nutrients, it does ensure that they are excreted rather than crossing the gastrointestinal barrier and into the blood stream. Oxalates that are not safely metabolized or bound by minerals in the gastrointestinal tract and excreted are then absorbed through the gastrointestinal barrier and enter the bloodstream.

The key site for problems with accumulation of oxalates in the bloodstream is the kidneys. Blood is filtered by the kidneys where oxalates are then excreted in the urine or returned back into the bloodstream depending on the saturation level and filtration rate of the kidneys. High oxalates in the kidneys tend to combine with calcium to form calcium oxalate stones, the most common type of kidney stone. High oxalates in the bloodstream tends to bind with essential elements such as calcium, magnesium, iron and copper and end up deposited in body tissues causing damage and exacerbating pain and inflammation. The most common location is in the joint or connective tissues, but these crystal deposits have also been found in the heart, brain, and even in the bones.

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Melinda Keen