Study: Walnuts Slow Prostate Cancer Growth, Reduce Cholesterol

WalnutsStillLife3The California Walnut Board partially sponsored a study that found walnuts slow prostate cancer growth in mice:

TRAMP Prostate Tumor Growth Is Slowed by Walnut Diets Through Altered IGF-1 Levels, Energy Pathways, and Cholesterol Metabolism, Journal of Medicinal Food, 29 October 2014

Mice were fed one of three diets – one with whole walnuts (diet group WW), walnut-like fat (diet group WLF, oils blended to match walnut’s fatty acid profile), or walnut oil (diet group WO, pressed from the same walnuts as WW). They found:

  • The prostate tumor size, plasma insulin-like growth factor-1 (IGF-1), high density lipoprotein (HDL), and total cholesterol all decreased significantly (P<.05) in both WW and WO compared to WLF.
  • Both WW and WO versus WLF showed increased insulin sensitivity, and tissue metabolomics found reduced glucose-6-phosphate, succinylcarnitine, and 4-hydroxybutyrate in these groups suggesting effects on cellular energy status. Tissue mRNA levels also showed changes suggestive of altered glucose metabolism with WW and WO diet groups having increased PCK1 and CIDEC mRNA expression, known for their roles in gluconeogenesis and increased insulin sensitivity, respectively.
  • WW and WO group tissues also had increased MSMB mRNa a tumor suppressor and decreased COX-2 mRNA, both reported to inhibit prostate tumor growth.

They concluded:

Walnuts reduced prostate tumor growth by affecting energy metabolism along with decreased plasma IGF-1 and cholesterol. These effects are not due to the walnut’s omega–3 fatty acids, but due to component(s) found in the walnut’s fat component.

Here’s the press release:

‘Tis The Season To Indulge In Walnuts, UC Davis Research Finds Walnuts Slow Prostate Cancer Growth, Among Other Health Benefits, University of California Davis Health System, 13 November 2014

This was interesting … Paul Davis, the lead researcher said:

“The energy effects from decreasing IGF-1 seem to muck up the works so the cancer can’t grow as fast as it normally would,” Davis said. “Also, reducing cholesterol means cancer cells may not get enough of it to allow these cells to grow quickly.”

So, lower cholesterol means slower cancer growth? How about that.

I’m wary of a study that’s funded by a group that benefits from the study’s results. I also think it’s more important to look at the whole diet instead of focusing on a particular food or nutrient. There are no magic foods. Before you know it, someone will take the results of this reductionist study, develop a walnut oil supplement, and sell it as a cancer cure.

Still, I think nuts are a great food. And I can’t help but be swayed here. To me, a diet that includes nuts is better than a diet that excludes them.

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