Have Your Estrogen and Eat it Too: Phytoestrogens in Soy may Support Kidney Health, Study Finds

Estrogen may play a key role in reducing the impact of kidney disease, say researchers in the Department of Molecular and Cellular Biology.

Kidneys work as our blood’s custodians, filtering out the waste produced by our cells and eliminating it through urine. When kidneys become diseased, this filter can become damaged such that waste products build up in our blood and important regulatory components are lost. For patients with advanced kidney disease, dialysis or a kidney transplant are the only treatment options.

While kidney disease is a worsening public health concern for everyone, previous studies have shown it is more devastating in men than in women. Dr. Nina Jones and her team of researchers set out to determine the molecular basis of this intriguing sex difference.

In a study published in the Canadian Journal of Kidney Health and Disease, the researchers determined that female mice had higher levels of two proteins (nephrin and Akt) in their kidney cells compared to males. Because these proteins are important for normal cell communication or “signaling”, and help regulate cell survival, this difference could explain why men develop more severe kidney disease than women.

“As we see in this paper, there are pretty large signaling differences between males and females,” says Casey Williamson, a PhD student who co-led the study with colleague Afreeda Mahesaniya. “Now we have a better idea of what is happening at the molecular level.”

Building on previous studies showing that these proteins are influenced by estrogen signaling, the results bolster the theory that the female sex hormone may be a significant contributor to women’s reduced susceptibility to kidney disease progression.

Plant-based compounds resembling estrogen can be consumed through diet, which may help balance certain hormone signals across sexes. These “phytoestrogens”, found in soy foods, can act on a subset of the same receptors as estrogen in the body.

To test whether phytoestrogens can imitate the beneficial effects of estrogen on kidneys, the researchers fed mice a diet enriched with soy, with encouraging results. The soy diet increased levels of nephrin and Akt protein in the kidneys of male mice. Female mice also benefited from the same diet, experiencing an even greater increase in nephrin and Akt.

In a final test to confirm that these plant compounds can support kidney health, the researchers applied a purified phytoestrogen found in soy called daidzein directly to cultured human kidney cells. The treatment successfully decreased the activity of another signaling pathway that is associated with cell death when it is triggered for prolonged periods.

“What we are doing here is providing a building block for understanding how food affects our cell signaling and our body,” says Williamson. “Knowing the pathways that are being changed with soy is a very important tool, alongside medicine, for hopefully mitigating those diseases.”

So does this mean soy is the answer to kidney disease? Not necessarily, says Williamson.

“Soy is incredibly complicated,” she warns. “While these results are intriguing, the full story is never just as simple as one study.”

This study was funded by the Ontario Ministry of Agriculture, Food and Rural Affairs (OMAFRA)-University of Guelph Partnership Program, with support from Soy 20/20 (currently Oil Seed Innovation Partners).

Read the full study in The Canadian Journal of Kidney Health and Disease

Read about other CBS Research Highlights.