In the last month alone, the findings of two or three single-agent studies have been widely reported. A Dutch study found no link between vitamins and dietary fiber upon stomach cancer. According to a study in the Journal of the National Cancer Institute, beta-carotene pills afford no protection against cancer. And a study of soy pills for hot flashes in women with breast cancer found no positive results. The failure of these single-agent studies may cause people to lose sight of the central concept behind the research.
Trials focusing on single substances often show little or no protective effect.
But the protective effects of such substances in combination with other compounds found in a healthy plant-based diet have been extensively documented, Butrum said. A Global Perspective examined over 4,500 international studies on the link between diet and cancer. The report found convincing evidence that a predominantly plant-based diet rich in a variety of fruits, vegetables, whole grains and beans significantly reduces cancer risk. Ultimately, researchers hope to determine how the many substances in these foods work in combination. After mapping out these important synergistic effects, they will be able to design healthy diets rich in foods that interact with each other for optimal disease-fighting benefits.