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American Chestnut Tree Leaf Tea for Mitigating Kidney Stone Disease Occurrence

Reduces Oxalate Levels in Tea, Presenting a Potential New Kidney Stone Therapeutic for High-Risk Individuals

The leaves obtained from a genetically modified American Chestnut Tree (ACT) reduce oxalate levels in commercially available teas, when added, lowering the risk of kidney stone development in high-risk tea drinkers. Kidney stones affect about 10% of the U.S. population, costing over S10 billion to treat, annually. Many stone formers excrete excessive amounts of oxalate in their urine due to the over-ingestion of oxalate from dietary sources. Tea is high in soluble oxalate, and its intake is generally not advised in calcium oxalate kidney stone formers. The American chestnut tree, once considered the most important North American forest tree, had become functionally extinct due to the “chestnut blight,” caused by Cryphonetria parasitica, a fungus that secrets oxalic acid at lethal levels. However, in the 1990s, Darling 58, a transgenic ACT that overexpresses wheat oxalate oxidase to degrade oxalate and resist blight, was developed.


Researchers at the University of Florida have discovered the addition of Darling 58 ACT leaves to commercially available teas reduces their oxalate levels. American Chestnut Tree leaves, alone or in combination with tea leaves, may serve as a potential therapeutic to reduce oxalate levels and mitigate renal stone occurrence in stone formers wanting to enjoy the health benefits of freshly brewed tea.




Addition of Darling 58 American Chestnut Tree leaves to tea, reducing soluble oxalate levels and stone disease occurrence in high-risk individuals



  • Addition of ACT leaves to tea leads to a great reduction in soluble oxalate levels, allowing high-risk stone formers to enjoy the health benefits of tea
  • Reduction of soluble oxalate levels in tea could reduce urine oxalate levels, mitigating renal stone risk in stone formers and reducing treatment costs
  • Oxalate-related disorders are not limited to stone disease, and include renal failure, inflammatory bowel disease, cystic fibrosis, autism, or breast cancer, widening the potential therapeutic options of ACT leaves
  • Use of ACT leaves as a therapeutic option for stone disease could increase the ACT commercial value, serving as an incentive to restore this lost ecosystem of North America
  • ACT leaves could be administered not only with tea but also with other oxalate-rich foods or beverages, increasing the number of possible therapeutic strategies



Darling 58, a genetically modified American Chestnut Tree, overexpresses wheat oxalate oxidase (OxOx) to degrade oxalate and resist chestnut blight. ACT leaves overexpressing OxOx can lower tea soluble oxalate levels, turning them into a potential therapeutic to reduce urinary oxalate levels in tea drinkers who are at high risk of developing renal stones.

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