Colorectal cancer risk lowered by whole grains but increased by processed meats, says study

Sep 7 2017

A new study conducted by the American Institute for Cancer Research (AICR) and the World Cancer Research Fund (WCRF) found that the daily intake of grains, such as those from whole-wheat bread or brown rice reduces the risk of colorectal cancer; the risk is expected to decrease with the increase in the amount of gains consumed.

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This study is the first of its kind where AICR/WCRF associated whole grains independently to lower cancer risk.

The report, titled ‘Diet, Nutrition, Physical Activity and Colorectal Cancer’ has also found that regular consumption of processed meat, such as hot dogs and bacon increased colorectal cancer risk and showed strong indications that physical activity protects against colon cancer.

Edward L. Giovannucci, MD, ScD, lead author of the report and professor of nutrition and epidemiology at the Harvard TH Chan School of Public Health explained: "Colorectal cancer is one of the most common cancers, yet this report demonstrates there is a lot people can do to dramatically lower their risk".

This new report analyzed 99 scientific research papers from across the world on how diet, physical activity and weight, influence the risk of colorectal cancer. More than a quarter of the 29 million people involved in the studies were diagnosed with colorectal cancer.

Colorectal cancer was also found to be increased by consuming excess amounts of red meat like pork or beef (more than 500 grams cooked weight per week); being obese or overweight, and taking two or more alcoholic drinks daily (30 grams of alcohol).

The researchers concluded that the daily consumption of nearly three serving (90 g) of whole grains can reduce colorectal cancer risk by 17 %. This complements prior findings indicating that high-fiber foods lower the risk of this cancer.

While considering physical activity, more physically active people possess a decreased risk of colon cancer than less physically active people. This condition was not found applicable for rectal cancer.

Among men and women in the US, the third most prevalent cancer is colorectal cancer with approximately 371 cases diagnosed per day.

As estimated by AICR, 47 % of the colorectal cancer cases in the country could be prevented by healthy lifestyle changes each year.

Giovannucci noted that the avoidance or cessation of smoking would also lower the risk.

A few other links between colorectal cancer and diet that were visible but unclear, were also identified by the researchers.

The risk was shown to marginally increase with reduced consumption of non-starchy fruits and vegetables, with consumption of less than 100 g each day (around a cup).

Increased intake of fish as well as foods containing vitamin C (such as oranges, strawberries and spinach) were also linked to lower colorectal cancer risk.

According to Alice Bender, AICR Director of Nutrition Programs, the studies that continue to emerge point to the positive effects of a plant-based diet.

She suggests replacing some of the refined grains with whole grains and increasing intake of plant foods (like fruits, vegetables and beans) in order to have a diet which includes cancer-protective compounds. This might also help in managing weight, which is another factor to lower risk, she added.