Oxalates: Everything You Need To Know About How These Food Compounds Can Affect Your Health


The more you learn about nutrition, the more you realize that healthy eating isn’t quite as simple as it seems. It’s not just about filing your plate with diverse and colorful plant-base items and calling it a day; unfortunately, truly optimizing your nutrition requires you to really dig into what ingredients are found in all those foods and whether or not they are healthy for YOU — because there’s no single diet that’s right for everyone. 

One of those ingredients to be aware of are oxalates. Keep reading for everything you need to know about oxalates and why you may need to be aware of them.


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What are oxalates? 

Oxalates are compounds that naturally occur in a variety of foods, including very healthy foods like berries, leafy greens, and beans. Like lectins, oxalates are present in plants to help protect them from insects and disease. When it comes to humans, they are considered anti-nutrients because when they are eaten, they can interfere with the absorption of other important vitamins and minerals, including iron, which is one of the most common nutrient deficiencies, and calcium, which is critical for strong bones. 

Oxalate’s antinutrient qualities can create issues that go beyond just nutrient deficiencies too. When oxalates bind to calcium, they can form calcium oxalate crystals. These crystals prevent calcium from being absorbed and utilized and can contribute to diseases such as osteomalacia and rickets. They can also travel through the body, causing muscle pain. And if they make it to the kidney they can cause kidney stones. That’s why, if you Google oxalates, the first search results have to do with low-oxalates diets to prevent kidney stones. 

What foods are high in oxalates? 

For most people, oxalates in food aren’t a big deal and we simply excrete them through waste. That said, for those who are sensitive to oxalates, high-oxalate foods can cause abdominal pain, nausea, muscle weakness, and burning and tingling in the mouth and throat. If you are prone to kidney stones or oxalate issues, you may also want to try and avoid high-oxalate foods. Some common high-oxalate foods include: 

  • Beans
  • Beets
  • Berries
  • Black pepper 
  • Broccoli
  • Cauliflower
  • Chocolate
  • Chard
  • Oranges
  • Kale
  • Nuts
  • Spinach
  • Radishes
  • Rhubarb 
  • Tofu

These are the foods highest in oxalates but the truth is, oxalates are present to some degree in basically every healthy plant food, which means they are impossible to avoid entirely. And you wouldn’t want to, either! If you gave up all oxalate-rich foods, you’d be giving up all the best high-fiber, phytonutrient-rich foods in the world. The good news is that many of these foods, which are high in oxalates, are also high in calcium, which means even if the oxalates do block some of the calcium, you are still getting some calcium with them. Two in particular that you can increase your intake of are kale and broccoli, which at 41% have a better calcium absorption rate than traditional milk (32%). (1) 

The other good news is that by cooking your food in a certain way, you can reduce the oxalate content and eliminate the negative effects of oxalates. 

How do you reduce oxalates in food? 

There are quite a few different methods for reducing oxalates in foods. The first one applies to most oxalate-rich foods, including leafy greens and cruciferous vegetables, and that is simply to cook them. You can do this by sautéing them, steaming them, baking them, or slow cooking them. Heat helps break down oxalates and makes them less irritating to your digestive system and less likely to act as antinutrients. 

For nuts, beans, and seeds, soaking is the best method to remove oxalates. You can sometimes buy these foods pre-soaked from the store, but soak them in water for 12 hours, drain them, then roast them yourself at a low-to-medium temperature for 10 to 20 minutes (or dehydrate them, if you have a food dehydrator).

Oxalates are compounds that we should all be aware of, especially if we have kidney stones in our family or in our health history, but they’re nothing to panic about, either. For most of us, we can simply make an effort to eat high-oxalate foods cooked.

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  1. Heaney, R., Weaver, C., Hinders, S., Martin, B., & Packard, P. (1993). Absorbability of calcium from Brassica vegetables: broccoli, bok choy, and kale. Journal of food science, 58, 1378-1380. doi: 10.1111/j.1365-2621.1993.tb06187.x

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Dr. Will Cole, IFMCP, DNM, DC, leading functional medicine expert, consults people around the world via webcam and locally in Pittsburgh. He received his doctorate from Southern California University of Health Sciences and post doctorate education and training in functional medicine and clinical nutrition. He specializes in clinically researching underlying factors of chronic disease and customizing a functional medicine approach for thyroid issues, autoimmune conditions, hormonal imbalances, digestive disorders, and brain problems. Dr. Cole was named one of the top 50 functional medicine and integrative doctors in the nation and is the best selling author of Ketotarian and The Inflammation Spectrum.