Eating soy and tomato may help prevent prostate cancer
Washington: Tomatoes and soy foods may be more effective in preventing prostate cancer when they are eaten together than when either is eaten alone, according to a new study.
"In our study, we used mice that were genetically engineered to develop an aggressive form of prostate cancer. Even so, half the animals that had consumed tomato and soy had no cancerous lesions in the prostate at study`s end," said John Erdman, a University of Illinois professor of food science and nutrition.
"All mice in the control group - no soy, no tomato - developed the disease," Erdman said.
From the time they were 4 to 18-weeks-old, the animals were fed one of four diets: 10 per cent whole tomato powder; 2 per cent soy germ; tomato powder plus soy germ; and a control group that ate neither tomato nor soy.
The 4 to 18-week time frame modelled an early and lifelong exposure to the bioactive components in these foods, he said.
"Eating tomato, soy, and the combination all significantly reduced prostate cancer incidence. But the combination gave us the best results. Only 45 per cent of mice fed both foods developed the disease compared to 61 per cent in the tomato group, and 66 per cent in the soy group," he said.
Prostate cancer is the most frequently diagnosed cancer in men, but the disease has nearly a 100 per cent survival rate if it`s caught early.
In older men, it is often a slow-growing cancer, and these men often choose watchful waiting over radiation and surgical treatments that have unwelcome side effects, said Krystle Zuniga, co-author of the paper.
In countries where soy is eaten regularly, prostate cancer occurs at significantly lower levels, Erdman noted.
"The results of the mouse study suggest that three to four servings of tomato products per week and one to two servings of soy foods daily could protect against prostate cancer," Zuniga said.
"It`s better to eat a whole tomato than to take a lycopene supplement. It`s better to drink soy milk than to take soy isoflavones. When you eat whole foods, you expose yourself to the entire array of cancer-fighting, bioactive components in these foods," Erdman said.