Why Do Oxalate Levels Vary?

Harvard recently updated its oxalate list—you can read about that here—and many of you were concerned that the numbers had changed and demanded answers! I hope our time together today helps you understand the big picture so you can feel less overwhelmed about this change.

The worry over the new list is ironic because, for decades, people have asked me, “When is Harvard going to update its list?” If you watched this week’s podcast episode about the Harvard update, you’ll know I was excited as a kid on Christmas morning! I couldn’t wait to share the news with you.

However, from the thousands of emails I received, it seems the news left many people worried and wondering how the numbers for certain foods could have changed so much (those darn blueberries!).

Studying oxalate levels is complicated. Many variables come into play when explaining why you see different values for the same type of food. We’ll discuss those in a bit.

Regardless of what any oxalate list reports, I’ve always advocated for a diverse diet. The variability in oxalate levels underscores the importance of not relying on a few foods. Eating a wide variety of foods is not only beneficial for our gut and overall health, but it also allows us to enjoy a more exciting and varied diet.

But I know all too well—because I’ve worked with thousands of people over the past 25 years—that people tend to eat the same oatmeal with blueberries daily because it’s easy. Blueberries were eaten all day because they were low in oxalate. Now, Harvard reports that blueberries are higher in oxalate and people are troubled.

Because raspberries are now listed low, many will gobble them down. Personally, I never stopped eating them when they were listed as high because I paired them with my Greek yogurt and only ate a few alongside many different fruits, not just blueberries. But I will not start buying bushels of raspberries, and I hope you don’t either.

My job is less about teaching people about oxalate and more about how to look at food differently. My teachings have always been to “eat a wide variety of foods in reasonable portions.” That is what has helped lower my patients’ and students’ urine oxalate. Why would you need me if this was as simple as downloading a list?

Kidney stone prevention is about habits, lifestyle, sugar, salt, calcium, and fluids. Once you eliminate the highest-oxalate foods, like spinach and almond products, oxalate is the least important part of preventing kidney stones.

My dream is for people to be hyper-focused on sugar and sodium. Think how much illness could be wiped away. Obesity rates would plummet. We could watch heart disease and diabetes rapidly decline. Oh, what a happy day that would be for me!

People who work with me learn that very quickly. That is why they lose weight, get off diabetic and blood pressure meds, and change their lifestyle. They no longer obsess about oxalate (they all did at first) and eat without fear. Working with me will change your life if you are ready to work. See what people say here. 

Here are some reasons why oxalate varies from list to list, decade over decade, and plant to plant.

1. Different amounts in different foods: The amount of oxalate in the same type of food can vary greatly depending on where and how it’s grown.
2. Various Ways to Measure: Scientists use different methods to check oxalate levels, which can give different results. Some methods might be better at detecting small amounts or different types of oxalate. (This is very important, and methods have gotten much more sophisticated since the last time Harvard reported.)
3. How Food is Prepared: How food is cooked can affect its oxalate content. For example, boiling spinach might lower its oxalate content because some got into the water.
4. Not All Oxalates Are Absorbed the Same: Just because a food has oxalates doesn’t mean your body absorbs them.
5. Different Forms of Oxalates: Oxalates can be found in foods as free acids or as part of salts, and their different forms can affect their impact on health and how they’re measured.
6. People Are Different Too: Everyone’s body handles oxalates differently, depending on genetics and the bacteria in the gut.

Factors That Change Oxalate Levels in Foods:

• Plant Type: Different types of the same plant can have different amounts of oxalates.
• Farming Methods: How a plant is grown (like what kind of fertilizer is used or when it’s picked) can change the amount of oxalates.
• Weather and Soil: The environment where a plant grows, including the type of soil and weather conditions, affects oxalate production.
• Processing Food: When processed (like dried or canned), the oxalate levels of food can change.
• Cooking Methods: Cooking methods like boiling, steaming, or frying can increase or decrease oxalate levels.

These factors make it quite complicated to pinpoint exact oxalate levels in foods. This will never change.

As you know, I like to take heavy-duty science and make it easier to understand. I typically save the science stuff for my mentor, Dr. Fred Coe. By the way, we will meet next week so I can update him on all of these changes.

Here are just a few studies on why oxalate levels are inconsistent. They validate everything I have been telling you over the years.

• Oxalate in Foods: Extraction Conditions, Analytical Methods, Occurrence, and Health Implications
• Food Oxalate: Factors Affecting Measurement, Biological Variation, and Bioavailability
• Estimation of the oxalate content of foods and daily oxalate intake
• Analytical procedures and methods validation for oxalate content estimation
• Variation in oxalate content among corm parts, harvest time, and cultivars of taro
• Variation in Oxalic Acid Content among Commercial Table Beet Cultivars and Related Crops
• Oxalate Content of Food: A Tangled Web
• Effect of Cooking on Soluble and Insoluble Oxalate Contents in Selected Pakistani Vegetables and Beans
• Comparison of the estimates of the oxalate content of taro leaves and corms and a selection of Indian vegetables following hot water, hot acid and in vitro extraction methods

Humans do not like change, especially regarding changes that could affect health. I understand as I have my own health concerns, and I feel you. Please know, though, that you are safe with me. Listen to my advice, work with me in some capacity, or become a diligent follower of my podcast and blog, and you will soon be free of the hyper focus on oxalate.

Work with me to lessen your stone risk and change your life.

• The Kidney Stone Prevention Course (lowest price with the MOST experience in teaching).
• The Urine Collection Result Consult
• Meal Plan Subscription
• Group Accountability Calls
• Private Consult

I remain,
Your friend and advocate,
Jill