Are there foods that could prevent cancer? Well... studies show that a dietary pattern with lots of fiber, and perhaps along the lines of the Mediterranean diet, may be the most beneficial. In other words, it's not just one or a few "super-foods" that a person should eat, but an overall dietary pattern. But one specific food does appear beneficial for health - nuts, specifically tree nuts.
Researchers at the Yale Cancer Center followed a large group of stage 3 colon cancer patients after they had been treated for about 6.5 years, and looked at how frequently they consumed nuts. (Stage 3 colon cancer means it had spread to lymph nodes, but not to distant sites like the liver and lungs.) They found an association with frequent consumption (2 or more servings per week) of tree nuts (walnuts, hazelnuts, almonds, cashews, pecans, etc.) and a 42% lower incidence of the colon cancer recurring and 57% lower death rate. However, these findings did not apply to peanuts, which are legumes. [NOTE: One ounce or a handful of nuts is considered a serving.]
Why would nuts be beneficial? Generally speaking, nuts lower inflammation and insulin resistance. The lead researcher Dr. Charles Fuchs said that "behaviors that make you less insulin-resistant, including eating nuts, seem to improve outcomes in colon cancer". Parts of this research were discussed last year, but now it has been written up in the Journal of Clinical Oncology. From Science Daily: Nut consumption may aid colon cancer survival
People with stage III colon cancer who regularly eat nuts are at significantly lower risk of cancer recurrence and mortality than those who don't, according to a new, large study led by researchers at Yale Cancer Center. The study followed 826 participants in a clinical trial for a median of 6.5 years after they were treated with surgery and chemotherapy. Those who regularly consumed at least two, one-ounce servings of nuts each week demonstrated a 42% improvement in disease-free survival and a 57% improvement in overall survival.
"Further analysis of this cohort revealed that disease-free survival increased by 46% among the subgroup of nut consumers who ate tree nuts rather than peanuts," said Charles S. Fuchs, M.D., M.P.H., director of Yale Cancer Center and senior author of the study. Tree nuts include almonds, walnuts, hazelnuts, cashews, and pecans, among others. In contrast, peanuts are actually in the legumes family of foods.
Many previous studies have reported that nuts, among other health benefits, may help to reduce insulin resistance, a condition in which the body has difficulty processing the insulin hormone. Insulin resistance leads to unhealthy levels of sugar in the blood and is often a predecessor to type 2 diabetes and related illnesses. Earlier research among patients with colon cancer has revealed worse outcomes among those with lifestyle factors that heighten insulin resistance, such as obesity, lack of exercise, and a diet with high levels of carbohydrates that quickly raise levels of blood sugar. .... An earlier analysis of diets in the same patient cohort by Fuchs and his colleagues found a significant link between coffee consumption and reduced recurrence and mortality in colon cancer. [Original study.]