Antioxidants & Oxalates

An antioxidant is a substance found in certain foods that protects the body from free radicals. Free radicals can cause damage that increases the risk of cancer in the body. An oxalate is a naturally occurring substance made in humans, animals and plants. In addition to your body producing them, you can get oxalates from outside sources. Oxalates have been shown to increase the risk of kidney stones and kidney disease. In rare cases, oxalate consumption is dangerous. Foods rich in antioxidants are often the same as those rich in oxalates.

What Antioxidants Do

There are two types of antioxidants: direct and indirect. Direct antioxidants neutralize free radicals by attaching to them, rendering them useless so your body flushes them out of your system. In contrast, your body breaks down indirect antioxidants and uses them to strengthen its defenses against free radicals. According to the National Cancer Institute, significant evidence suggests that antioxidants might slow or prevent the development of cancer because of their free radical fighting abilities.

What Oxalates Do

Oxalates are mostly waste, either from your body or from foods you consume, that are flushed out through urination. The kidneys must process oxalates to remove them from the body. Most kidney stones are comprised of a combination of oxalates and calcium. Excessive oxalate consumption might lead to kidney disease and require treatment. If you have had high-oxalate kidney stones in the past, or have an increased risk of kidney disease, your health care professional might advise you to lower your oxalate intake.

Foods Containing Both Antioxidants and Oxalates

Fruits and berries that contain both antioxidants and oxalates include blackberries, blueberries, cranberries, figs, grapes, oranges, pears, plums, pineapples, raspberries and tomatoes. Almonds, peanuts and pecans are examples of nuts that contain both antioxidants and oxalates. Vegetables that contain both substances include asparagus, broccoli, eggplant, green beans, kale, lettuce, parsley, rhubarb, spinach and sweet potatoes. Other foods that contain both antioxidants and oxalates include black tea, chocolate, soy products and wheat germ.

Conclusion

Unless directed by your health care professional, you should not go out of your way to avoid foods containing oxalates. Instead, ensure you eat antioxidant-rich foods and stay properly hydrated with at least eight 8-ounce glasses of water daily to maintain healthy kidney function. Consuming fresh vegetables that contain both oxalates and antioxidants is generally better for you than eating fatty and sugary foods that do not contain either. If you are in doubt or have experienced kidney problems in the past, consult your health care professional and adjust your diet according to this advice.