“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,” according to a professor of nutrition at the Harvard School of Public Health in Boston, MA.

Bowel cancer is the 4th most common type of cancer in the world, as well as the 4th deadliest form of cancer.

Approximately 1.4 million new cases of bowel cancer are diagnosed annually worldwide.

Furthermore, 700,000 cancer deaths are thought to have been caused by colon cancer each year.

Whole grains and physical activity lower risk

The report looked at 99 studies from all over the world, summing up data on 29 million adults of whom 247,000 developed colorectal cancer.

The studies that the researchers examined included only randomized controlled trials, cohort studies, and so-called nested case-control studies.

After conducting meta-analyses of these studies, the researchers found that eating whole grains every day significantly reduces the risk of colorectal cancer, while the intake of processed meats raises the risk.

More specifically, eating more than 500 grams of cooked red meat (such as pork, beef, or lamb) every week raises the odds of developing colorectal cancer, with every 100 grams per day further increasing the risk by 12 percent.

The report also found that consuming more than two alcoholic drinks every day – or the equivalent of 30 grams of alcohol – as well as being overweight or obese further increases the risk.

By contrast, around three daily servings, or 90 grams, of whole grains (including brown rice and whole-wheat bread) can lower the risk of colorectal cancer by 17 percent.

Fruits and vegetables containing vitamin C, as well as fish, also seemed to lower the risk of colorectal cancer, although the evidence was not as clear and more data are needed.

Oranges, grapefruits, strawberries, kiwis, broccoli, spinach, and sweet red pepper are all sources of vitamin C.