March 2023 Should I be Avoiding Oxalates?
by Lacey Eadon
Oxalates have been a hot topic in the recent months as there is growing concern for “anti-nutrients” in our foods. There is a lot of talk about how oxalates can be harmful to health, but are they really a health threat? Have you wondered if you should be on a low-oxalate diet?
What are Oxalates?
Oxalates are natural compounds found in vegetables, fruits, nuts, and grains. Some examples of foods that are highest in oxalates include green leafy vegetables, soy, almonds, potatoes, tea, rhubarb, cereal grains and beets. Oxalates are also naturally created in the human body as a waste product.
Are Oxalates an “Anti-Nutrient”?
Oxalates can bind to calcium—and to a lesser extent—other minerals in the stomach and intestines. This binding can reduce absorption of these minerals inhibiting their ability to be used. For this reason, oxalates have been labeled an “anti-nutrient”. This label suggests that oxalates have a negative effect on nutrition status and health. However, this “anti-nutrient” effect is not as hindering as it may sound.
There are several factors that affect the level of oxalates in foods, including the growing season, weather conditions, and the plant variety. For example, Avon spinach may have a higher oxalate content than Butterflay spinach. Cooking also significantly reduces oxalate content in food. Although certain foods may contain residual amounts of oxalates after cooking, the health benefits of eating these foods will likely outweigh any potential negative nutritional effects.
Further, a specific type of bacteria that resides in the gut called Oxalobacter formignes breaks down oxalates and uses them for energy. This process prevents oxalates from binding to minerals and limiting their absorption. Studies have shown that people with low levels of oxalate-degrading bacteria in the gut and those with certain digestive disorders are more prone to higher levels of oxalates in the body.
Are Oxalates Bad for the Kidneys?
Oxalates can bind to minerals like calcium in the kidneys and form calcium oxalate kidney stones – the most common type of kidney stone. For most people, these compounds are usually removed in the urine. However, accumulation of these compounds may occur in some people potentially leading to kidney stones. Surprisingly, most urinary oxalates are actually the ones formed naturally as a waste product in the body, less so from dietary oxalate. However, for those prone to oxalate kidney stones, a lower oxalate diet could still be beneficial to limit the number of oxalates reaching the kidneys. Cutting the oxalate-rich foods in your diet alone will not reduce the likelihood of forming calcium oxalate kidney stones as reducing dietary oxalate is not the only way to avoid kidney stones. In fact, drinking sufficient amounts of water to dilute urine to prevent oxalate collection in the kidneys remains the #1 recommendation.
Should I be Eating a Low Oxalate Diet?
In most cases, a low-oxalate diet is not necessary. In fact, it is recommended to include many oxalate-containing plant foods in the diet as evidence suggests that these foods play a vital role in disease prevention. However, those who experience frequent oxalate kidney stones or have certain genetic and digestive disorders may want to speak with a physician and registered dietitian for guidance on treatment, which may include appropriately monitoring oxalate consumption.
About the Author:
Eadon is from Sarasota, FL, but moved to Fort Collins in 2019 to attend CSU. She just graduated from CSU with a degree in dietetics and nutrition management in May 2022. She is completing her dietetic internship through the University of Northern Colorado. Eadon has gotten to experience a lot of areas of dietetics through her internship program. As of right now, she is really interested in outpatient counseling. Her specific areas of interest are sports nutrition, eating disorder recovery, and functional nutrition (specifically pertaining to gut health). Read more about Eadon in her KRNC February 2023 Student Spotlight.
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