Diets rich in walnuts were found to help slow the growth of prostate cancer in mice.
Recent findings suggest walnuts and walnut oil also reduce cholesterol and the hormone IGF-1, which has been linked to prostate and breast cancer, UC Davis reported.
"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."
To make their findings researchers used a mixture of fats with the same fatty acid content as walnuts as a control diet. They then fed mice either the control diet or a diet rich in real walnuts or walnut or walnut oil. The team found walnuts and walnut oil helped reduce prostate cancer growth, while the walnut replica diet did not, These findings suggest there is another cancer-fighting compound present in walnuts besides 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."
The study was not able to pinpoint the ingredient in walnuts that slows cancer growth, but it did rule out fiber, zinc, magnesium and selenium; they were also able to pinpoint several meachanism that could slow cancer growth present in the walnuts.
"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."
Research conducted on mice does not always translate to humans, but the researchers still recommend increasing walnut consumption to ward off prostate cancer. A past PREDIMED study that looked at the influences of the Mediterranean diet found eating walnuts reduced the risk of prostate cancer mortality. Despite the findings, the researchers warn walnuts should still me eaten in moderation.
"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.
The findings were published in a recent edition of the Journal of Medicinal Food.
