Is kale high in oxalic acid?


Kale has become an incredibly popular leafy green in recent years, prized for its nutrition and versatility. However, some people worry that kale may be high in oxalic acid, a compound that can bind to minerals like calcium and prevent absorption. In this article, we’ll take a detailed look at the oxalic acid content of kale and what it means for your health.

What is Oxalic Acid?

Oxalic acid is an organic compound found in many plant foods. Also known as ethanedioic acid, it plays a role in the metabolism process of plants. For humans, it has little nutritional benefit and cannot be metabolized effectively.

When we eat foods containing oxalic acid, it can bind to minerals like calcium and iron in the digestive tract, preventing absorption. Over time, this can potentially lead to nutrient deficiencies if high-oxalate foods are consumed regularly without supplementation.

Foods highest in oxalic acid include spinach, beet greens, rhubarb, strawberries, nuts, chocolate, tea, and wheat bran. Let’s take a closer look at the oxalic acid content of kale and what it means for your mineral intake.

Oxalic Acid Content of Kale

Kale contains oxalic acid like most plant foods, but is it considered high in this compound? Here’s a look at the typical oxalic acid content of raw kale per 100g serving:

Food Oxalic Acid (mg per 100g)
Kale 97mg

For comparison, here are the oxalic acid levels in 100g of other common vegetables:

Food Oxalic Acid (mg per 100g)
Spinach 750mg
Broccoli 90mg
Asparagus 13mg
Green beans 10mg

As you can see, kale contains a moderate amount of oxalic acid. It has approximately 10x less oxalic acid than spinach, which is considered very high in oxalates.

Other greens like broccoli, asparagus, and green beans contain minimal amounts in comparison. So kale is moderate compared to other vegetables, and should not be classified as a high oxalate food.

Health Impacts of Kale Oxalates

For most people, the moderate oxalic acid content in kale is not a major concern. Let’s discuss who may want to limit oxalate intake from kale:

– Those prone to kidney stones – High oxalate diets are linked to an increased risk of calcium oxalate kidney stones in susceptible individuals. Reducing kale and other oxalate-rich foods may help prevent recurrent kidney stones.

– People with malabsorption issues – Individuals with Crohn’s disease, digestive disorders, and other conditions that impair mineral absorption are at a higher risk of oxalate-binding causing nutrient deficiencies. Limiting dietary oxalates from greens like kale may be beneficial.

– Others aiming to maximize calcium absorption – For those wanting to optimize calcium levels, especially children and older adults, minimizing kale oxalates through cooking and limiting portions may be advisable.

For most healthy adults, kale can be enjoyed as part of an overall balanced low-oxalate diet. Cooking kale reduces oxalic acid content by 10-15%, providing added benefits.

Tips for Low-Oxalate Kale Consumption

Here are some tips for people wanting to keep kale oxalates low while still enjoying its nutritional benefits:

– Cook kale – Lightly steaming or boiling kale for a few minutes can lower oxalic acid content. Sauteing and baking also helps reduce oxalates.

– Limit portions – Stick to about 1/2 – 1 cup cooked kale per day as part of a varied diet to prevent excessive oxalate intake.

– Pair with calcium-rich foods -Consuming kale with milk, cheese, yogurt or other calcium sources can help offset the effects of oxalate binding.

– Drink plenty of fluids – Getting enough fluids daily is important to flush out excess oxalates and prevent kidney stone formation.

– Rotate greens – Vary your leafy greens beyond just kale. Choose lower-oxalate greens like arugula, romaine, cucumber, celery, and herbs frequently.

Health Benefits Beyond Oxalates

While oxalic acid content is one factor to consider, remember kale offers many other valuable nutrients:

– Vitamin K – Kale provides plentiful vitamin K, with one cup meeting over 600% of the RDI. Vitamin K supports bone and heart health.

– Vitamin C – Kale is high in immune-boosting vitamin C. Per calorie, kale provides more vitamin C than an orange.

– Antioxidants – Kale contains antioxidants like quercetin and kaempferol that may help lower inflammation and oxidative stress.

– Vitamin A – As a leafy green, kale is an excellent source of provitamin A carotenoids like beta-carotene.

– Folate – Kale provides a good amount of folate, an important B vitamin for cell growth and development.

So while oxalic acid in kale is worth being mindful of, it remains one of the most nutrient-dense vegetables you can eat. Its many vitamins, minerals, antioxidants and compounds make it a healthy addition to balanced diets for most people.


Kale contains moderate amounts of oxalic acid compared to other leafy greens like spinach. For those prone to kidney stones or with nutrient malabsorption issues, limiting kale consumption and total dietary oxalates can be beneficial. However, for most people kale can be enjoyed regularly as part of varied low-oxalate diet.

Cooking kale reduces its oxalate content slightly. Consuming kale along with foods high in calcium and magnesium can also help offset mineral absorption inhibitors. Drinking adequate fluids daily helps flush out excess oxalates as well.

While its oxalic acid content needs to be kept in mind, kale remains one of the most nutritious vegetables available, packing high amounts vitamins, minerals and antioxidants in each low-calorie serving. Using cooking techniques and portion control can allow most people to reap kale’s many benefits while not going overboard on dietary oxalates.

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