Diet and colorectal cancer

This review explored the relationship between dietary supplements and colorectal cancer outcomes.

The prevalence of colorectal cancer has steadily increased over the past 50 years. Dietary changes and decreased physical activity have led to an obesity epidemic in the western world, a known risk factor for many diseases including colorectal cancer. Multiple studies have found associations between diet and the risk of developing colorectal cancer. However, recent studies investigating the association between diet and cancer outcomes or the risk of cancer recurrence have reported inconclusive results. This review analyzed all recently published research regarding the role of dietary supplementation in the management of colorectal cancer.

The risk of developing colorectal cancer was found to be associated with multiple dietary factors, including red meat, animal fat, dietary fibers and calcium. In a study including 130,000 participants, those who did not frequently consume saturated animal fats, such as those found in red meat, reduced their risk of developing colorectal cancer by more than 20%. A fiber rich diet, including plenty of whole wheat, bran, fruits and vegetables, was found to protect against recurrence of adenomas and polyps (non-cancerous growths which significantly increase the risk of colorectal cancer) after their removal.  However, one study reviewed found that a fiber rich diet significantly decreases survival among patients diagnosed with advanced colorectal cancer. High amounts of dietary folic acid (found mainly in dried beans and dark green vegetables) was shown to be associated with a decreased risk of both colorectal cancer and adenoma recurrence. However, folic acid supplements (taken as a daily pill) have been found to increase the risk of adenoma recurrence. High calcium intake was also found to reduce the risk of developing colorectal cancer by 22% compared to low calcium intake. A three year study found that high calcium intake, with or without added vitamin D supplementation, protected patients against recurrences of polyps, adenomas and colorectal cancer. Physical activity and regular exercise are known to protect against the development of colorectal cancer. Several recent studies have shown that high levels of physical activity significantly prolong survival among colorectal cancer patients of all stages, and may reduce recurrence rates by up to 40%.

This review concluded that diet and activity may play a role in prolonging survival and reducing recurrence rates among colorectal cancer patients.