UC Davis research finds walnuts slow prostate cancer growth, among other health benefits
Researchers at UC Davis and other institutions have found that diets rich in whole walnuts or walnut oil slowed prostate cancer growth in mice. In addition, both walnuts and walnut oil reduced cholesterol and increased insulin sensitivity. The walnut diet also reduced levels of the hormone IGF-1, which had been previously implicated in both prostate and breast cancer. The study was published online in the Journal of Medicinal Food.
“For years, the United States government has been on a crusade against fat, and I think it’s been to our detriment,” said lead scientist and research nutritionist Paul Davis. “Walnuts are a perfect example. While they are high in fat, their fat does not drive prostate cancer growth. In fact, walnuts do just the opposite when fed to mice.”
Davis and colleagues have been investigating the impact of walnuts on health for some time. A previous study found that walnuts reduced prostate tumor size in mice; however, there were questions about which parts of the nuts generated these benefits. Was it the meat, the oil or the omega-3 fatty acids? If it was the omega-3 fats, the benefit might not be unique to walnuts. Since the fatty acid profile for the soybean oil used as a control was similar, but not identical, to walnuts, more work had to be done.
In the current study, researchers used a mixture of fats with virtually the same fatty acid content as walnuts as their control diet. The mice were fed whole walnuts, walnut oil or the walnut-like fat for 18 weeks. The results replicated those from the previous study. While the walnuts and walnut oil reduced cholesterol and slowed prostate cancer growth, in contrast, the walnut-like fat did not have these effects, confirming that other nut components caused the improvements – not the omega-3s.
“We showed that it’s not the omega-3s by themselves, though, it could be a combination of the omega-3s with whatever else is in the walnut oil,” Davis said. “It’s becoming increasingly clear in nutrition that it’s never going to be just one thing; it’s always a combination.”
While the study does not pinpoint which combination of compounds in walnuts slows cancer growth, it did rule out fiber, zinc, magnesium and selenium. In addition, the research demonstrated that walnuts modulate several mechanisms associated with cancer growth.
“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.”
In addition, the research showed increases in both adiponectin and the tumor suppressor PSP94, as well as reduced levels of COX-2, all markers for reduced prostate cancer risk.
Although results in mice don’t always translate to humans, Davis said his results suggest the benefits of incorporating walnuts into a healthy diet. Other research, such as the PREDIMED human study, which assessed the Mediterranean diet, also found that eating walnuts reduced cancer mortality.
Still, Davis recommends caution in diet modification.
“In our study the mice were eating the equivalent of 2.6 ounces of walnuts,” he said. “You need to realize that 2.6 ounces of walnuts is about 482 calories. That’s not insignificant, but it’s better than eating a serving of supersized fries, which has 610 calories. In addition to the cancer benefit, we think you also get cardiovascular benefits that other walnut research has demonstrated.
“It’s the holiday season, and walnuts are part of any number of holiday dishes. Feel free to consume them in moderation.”
Other researchers included Hyunsook Kim, Department of Physiology, College of Veterinary Medicine, Konkuk University, and Wallace Yokoyama, Processed Foods Research, Western Regional Research Center.
This study was funded by American Institute for Cancer Research (award MG10A001), the California Walnut Board and the KU-Research Professor Program of Konkuk University.
UC Davis Comprehensive Cancer Center
UC Davis Comprehensive Cancer Center is the only National Cancer Institute-designated center serving the Central Valley and inland Northern California, a region of more than 6 million people. Its specialists provide compassionate, comprehensive care for more than 10,000 adults and children every year, and access to more than 150 clinical trials at any given time. Its innovative research program engages more than 280 scientists at UC Davis, Lawrence Livermore National Laboratory and Jackson Laboratory (JAX West), whose scientific partnerships advance discovery of new tools to diagnose and treat cancer. Through the Cancer Care Network, UC Davis collaborates with a number of hospitals and clinical centers throughout the Central Valley and Northern California regions to offer the latest cancer care. Its community-based outreach and education programs address disparities in cancer outcomes across diverse populations. For more information, visit cancer.ucdavis.edu
Dorsey Griffith | EurekAlert!
Bioinspired nanoscale drug delivery method developed by WSU, PNNL researchers
10.01.2019 | Washington State University
How herpesviruses shape the immune system
09.01.2019 | German Center for Infection Research
World first experiments on sensor that may revolutionise everything from medical devices to unmanned vehicles
The new sensor - capable of detecting vibrations of living cells - may revolutionise everything from medical devices to unmanned vehicles.
Dead and alive at the same time? Researchers at the Max Planck Institute of Quantum Optics have implemented Erwin Schrödinger’s paradoxical gedanken experiment employing an entangled atom-light state.
In 1935 Erwin Schrödinger formulated a thought experiment designed to capture the paradoxical nature of quantum physics. The crucial element of this gedanken...
Cellulose obtained from wood has amazing material properties. Empa researchers are now equipping the biodegradable material with additional functionalities to produce implants for cartilage diseases using 3D printing.
It all starts with an ear. Empa researcher Michael Hausmann removes the object shaped like a human ear from the 3D printer and explains:
The phenomenon of so-called superlubricity is known, but so far the explanation at the atomic level has been missing: for example, how does extremely low friction occur in bearings? Researchers from the Fraunhofer Institutes IWM and IWS jointly deciphered a universal mechanism of superlubricity for certain diamond-like carbon layers in combination with organic lubricants. Based on this knowledge, it is now possible to formulate design rules for supra lubricating layer-lubricant combinations. The results are presented in an article in Nature Communications, volume 10.
One of the most important prerequisites for sustainable and environmentally friendly mobility is minimizing friction. Research and industry have been dedicated...
Just in time for Christmas, a Mars-analogue mission in Morocco, coordinated by the Robotics Innovation Center of the German Research Center for Artificial Intelligence (DFKI) as part of the SRC project FACILITATORS, has been successfully completed. SRC, the Strategic Research Cluster on Space Robotics Technologies, is a program of the European Union to support research and development in space technologies. From mid-November to mid-December 2018, a team of more than 30 scientists from 11 countries tested technologies for future exploration of Mars and Moon in the desert of the Maghreb state.
Close to the border with Algeria, the Erfoud region in Morocco – known to tourists for its impressive sand dunes – offered ideal conditions for the four-week...
16.01.2019 | Event News
14.01.2019 | Event News
12.12.2018 | Event News
17.01.2019 | Physics and Astronomy
17.01.2019 | Materials Sciences
17.01.2019 | Information Technology