Researchers analyzed information gathered from almost 46,000 men for 25 years and found that those who adopted five or six of the healthy habits had a 39 percent lower risk of developing lethal prostate cancer than those who adopted one or none of the habits, according to the results presented at the European Cancer Congress in Amsterdam.
In another study involving more than 21,000 men, the risk reduction was 47 percent, the Japan Times reported.
Each of the six habits, which also included not smoking, exercising, eating fatty fish and having a body-mass index of less than 30, has been linked with lowering prostate-cancer risk, but their joint effect hasn't been studied before, Stacey Kenfield, a University of California, San Francisco, researcher who presented the results, said.
The scientists are now studying which elements play the most important role in reducing cancer risk, she said.
Tomatoes contain lycopene, an antioxidant that can block the action of cell-damaging free radicals, according to the society's website.
In one of the two studies, men who only adopted the dietary habits had a 27 percent lower risk of lethal prostate cancer than those who adopted none. In the other study, the risk reduction was 48 percent.