The Kale Controversy: Separating Facts from Fear

Kale, often celebrated as a superfood, has recently come under scrutiny due to claims that it contains harmful substances such as oxalic acid, toxic metals, and per- and polyfluoroalkyl substances (PFAS), commonly referred to as “forever chemicals.” 

This article examines these concerns by analysing scientific research and regulatory perspectives to provide an evidence-based understanding of the potential risks and benefits associated with consuming kale.

Social Media Posts 

Social media posts are spreading, stating that Kale is a very toxic food, and those posts target the major food brand Pizza Hut. Those posts say Kale is not included in Pizza Hut foods, saying it is awful for human health, and Pizza Hut only uses Kale for decorative purposes in salad bars.

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Even web media has expressed their attention to the matter.

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We decided to do a fact-check on this.

Fact Check 

Claim 1. Oxalic Acid in Kale – Harmful or Manageable?

Oxalic acid is a naturally occurring organic compound found in many plants, including leafy greens, vegetables, fruits, cocoa, nuts, and seeds. In the digestive system, oxalate can bind with minerals like calcium, potentially reducing their absorption. High concentrations of oxalates may contribute to kidney stone formation in susceptible individuals. Read here and here

However, kale’s oxalate levels are remarkably low compared to other greens like spinach. According to studies, kale contains only about 2 milligrams of oxalates per cup, whereas spinach has significantly higher levels. Read here And here. 

For most individuals, this poses no health risk. However, people prone to kidney stones or specific health conditions may need to monitor oxalate intake. Experts recommend consuming kale as part of a balanced diet for its vast nutritional benefits while consulting healthcare providers when necessary.

Claim 2. Toxic Metals in Kale – Are They Significant?

Like other leafy greens, kale can absorb heavy metals such as cadmium, lead, and chromium from contaminated soil. Excessive amounts of these metals can harm human health, affecting the liver, kidneys, and nervous system. A study published in Environmental Monitoring and Assessment found heavy metal levels exceeding WHO/FAO limits in some leafy vegetables. However, contamination levels depend heavily on agricultural practices and soil conditions. Washing kale thoroughly and sourcing it from reputable suppliers minimizes potential exposure. Regulatory frameworks ensure that commercially sold kale generally remains within safe consumption limits. Read here

Claim 3. PFAS Contamination: Is Kale Affected?

Often called “forever chemicals,” PFAS are synthetic compounds widely used for their nonstick, water-resistant, and heat-resistant properties. They persist in the environment and bioaccumulate, raising concerns about potential health risks such as hormonal disruption, immune system effects, and cancer.

PFAS contamination in kale has been observed in some studies. A pilot study revealed that seven out of eight kale samples tested in the U.S. contained PFAS, likely due to factors such as polluted irrigation water or contaminated fertilisers. Read here

However, the FDA clarifies that environmental contamination does not necessarily lead to detectable PFAS levels in food. While this warrants vigilance, PFAS contamination in kale is not yet conclusively linked to widespread risk. Consumers can reduce potential exposure by buying organic produce and washing it thoroughly. Read here

Claim 4. For Which Purposes Does Kale Use in Pizza Hut?

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Until 2013, Pizza Hut was the largest consumer of kale in the United States, purchasing nearly 14,000 pounds in 2012. However, this kale was not used in their food offerings; instead, it served as a decorative element to enhance the appearance of their salad bars by covering the ice that kept ingredients cold. In 2013, Pizza Hut transitioned to refrigerated salad bars, eliminating the need for kale as decoration. Since then, the company has phased out salad bars in the U.S., focusing primarily on pizza, and currently does not include kale in its menu items. Read here

To provide clarity on the current use of kale in their menu offerings, we have reached out to Pizza Hut Sri Lanka’s media team and are awaiting their response. We will update the article as soon as we receive further insights into whether kale is included in their dishes today and their stance on its safety and nutritional aspects.

Conclusion

While concerns about oxalic acid, toxic metals, and PFAS are rooted in scientific observations, they are often exaggerated or misrepresented. The health benefits of consuming kale outweigh potential risks.