Oxalates

As promised on Monday, I am going to give a quick overview of oxalates. I think it’s important for people to understand what they are, which foods they are in, and how they impact which nutrients you obtain from your foods.

What are they?

Oxalates are organic acids, and are made inside of plants, animals and humans on a regular basis. They are considered binders, because they combine chemically with nutrients to form certain substances that the body simply cannot absorb. Oxalates occur naturally due to the incomplete oxidation of carbohydrates. Oxalates or oxalic acid is found in many foods in high levels; however, they are found in certain household products in toxic levels. These include things like bleaches, anti-rust products, and metal cleaners.

Which foods contain high amounts of oxalates?

• Berries
• Currants
• Kiwi
• Purple grapes
• Figs
• Tangerines
• Plums
• Rhubarb
• Spinach
• Eggplant
• Endive
• Swiss chard
• Beet greens
• Collard greens
• Okra
• Parsley
• Kale (so sad!)
• Leeks
• Legumes
• Quinoa
• Celery
• Green beans
• Sweet potatoes
• Almonds
• Cashews
• Peanuts
• Soy products
• Wheat bran
• Wheat germ
• Cocoa
• Chocolate
• Black tea
• Coffee

What do oxalates do to the nutrients in our food?

The oxalates in food will bind with certain nutrients and carry them right through our digestive tract and out of our body through the urine, preventing absorption. And if the nutrients are not absorbed, we are not getting any of their health benefits. It’s as if the food never contained them in the first place. Nutrients that are affected by oxalates include calcium, iron, zinc, copper, magnesium, and vitamin B6. The main nutrient affected, though, is calcium.

People with kidney problems, gout or rheumatoid arthritis are advised to avoid foods containing high amounts of oxalates as much as possible. This is because the oxalates form crystals that are very sharp, and although they are small, they are still large enough to irritate the body. When these crystals are deposited into our tendons, joints, kidneys or organs, we experience pain and eventually more serious health problems like the ones listed above. If you are trying to increase your calcium or iron intake, it may also be a good idea to cut back on foods high in oxalates. However, I’m hesitant to give this advice because so many foods that contain oxalates also contain many other beneficial nutrients that our body needs. I think a varied diet will help ensure that you are receiving all essential nutrients, and not consuming too much of one food that contains high amounts of oxalates.

For most people who do not have serious health problems, including foods with oxalates in the diet is fine. Just make sure you eat a varied diet and don’t consume large amounts of oxalate-rich foods for extended periods of time (for example, don’t make spinach your one and only green vegetable).

When we cook our foods, the oxalates decrease by about 10% at best. There is really no easy way (so far) to reduce oxalates in the above foods. The farm that Ed and I do our CSA with, Grant Family Farms, is supposedly working on a spinach plant that is very low in oxalates. Some of the farmer’s assistants came to our classroom last week to talk to us about organic farming, and mentioned this. I got really excited – hopefully that spinach will show up in our CSA box at some point!

So now you know about oxalates. Hopefully it’s not too disheartening – just remember that there are still so many good things in vegetables and eating all the oxalates in the world is still better than eating processed foods!