Kidney DiseaseTurmeric

Turmeric and the risk of kidney stones

In May 2008, researchers from the University of Wyoming in Laramie studied urinary oxalate excretion from supplemental doses of cinnamon and turmeric.

When oxalic acid in plants combines with calcium, iron, sodium, magnesium, or potassium it forms insoluble crystals called oxalates, which are deposited in the kidneys and lead to the formation of “stones.”

First, the details.

  • 11 healthy adults participated in this 8-week study.
  • They were assigned to take 2, 4-week treatments in random order.
    • Supplemental doses of cinnamon and turmeric that provided 55 mg oxalate/day.
    • Water that served as the comparative control.
  • Oxalate load tests were performed at the start of the study and after each treatment.
  • Fasting sugar and lipid blood concentrations were also measured.

And, the results.

  • Compared with taking cinnamon or water, turmeric led to significantly higher urinary oxalate excretion.
  • There were no changes in the other tests.

The bottom line?
The authors concluded, “Consumption of supplemental doses of turmeric can significantly increase urinary oxalate levels, thereby increasing risk of kidney stone formation in susceptible individuals.”

The question for consumers and healthcare professionals is, do all turmeric-containing products have the same amount of oxalic acid and the same level of risk?

An article at | Europe suggests that they don’t. Sabinsa Corporation reported that they measured the amount of oxalate in its product (Curcumin C3 Complex) and found “88 times lower [oxalate levels] than the lowest level needed for a food to be classified as ‘high oxalate’.”

This isn’t an endorsement of a particular product. But it’s not surprising that there might be differences among products. The source of turmeric used by the Researchers in Wyoming isn’t stated in the study abstract.

2/3/09 11:13 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.