A diet high in fiber from cereals and whole grains reduces the risk of colon cancer, according to a study published this month in the British Medical Journal. Fiber from fruits and vegetables, while also reducing risk, has weaker benefits against this type of cancer.

According to the study, colorectal cancer is the third most common type of cancer, accounting for about 9.7% of all cases of cancer – giving whole grains an important role to play in good health.

Researchers from Imperial College, London and the University of Leeds reviewed 25 studies involving almost two million people (including 14,500 cases of colorectal cancer) to arrive at their conclusions. Based on the data, they projected that consuming three servings a day of whole grains was linked with a nearly 20% reduced risk in colorectal cancer. The study also concluded that risk of this cancer dropped 10% for every 10 grams of fiber (that’s fiber, not whole grains — don’t confuse them!) in subjects’ diets.

Illustrations from Open Access article BMJ2011;343:d6617
 

This study is particularly interesting for a few reasons.

1. It examines the “dose-response” relationship between whole grain and colon cancer and between dietary fiber and colon cancer.

2. It shows that all fiber may not be equally protective against certain conditions.

3. It points out that whole grains’ benefits are likely due to more than just fiber.

Common sense tells us whole grains are better for you – with two and a half to five times more of most nutrients, how could they not be? And scores of studies show an association between whole grains and better health. But few studies have looked specifically at “dose-response” – the question of how much whole grain we should consume to get a particular benefit.

Only recently have studies begun to accurately document the amount of whole grain actually consumed, in ways that are reliable enough for research. The UK team looked at six studies with such data to conclude that three servings a day of whole grain foods is the sweet spot. The photo above shows what three servings could look like – as simple as two slices of whole grain bread and a bowl of whole grain cereal, as shown above.

The study actually refers to three servings as “90 grams of whole grains per day” – a confusing number that led us to contact lead author Dagfinn Aune. He said, “The weights refer to the weight of the food as it is consumed, so for some of the studies the actual whole grain content of a 30 gram serving may be less than 30 grams.” He clarified that “mixed” foods were included, but when foods contained small amounts of whole grains, only the whole grain proportion was counted.

Basically, then, when the study refers to 90 grams of whole grain, it is referring to three servings of about an ounce each – what the U.S. government refers to as three “ounce equivalents.”

Interestingly, the researchers went to great pains to make sure that no one study was skewing the results in one direction or another. Throughout their analysis of the data, they would pool data, then take out one study at a time and repeat the analysis, to see if the results changed. But their conclusions remained rock solid; “no particular study explained the results for colorectal cancer.”

So here’s the bottom line. Whole grains improve health. There are hundreds of whole grain foods out there to appeal to every taste. Why would anyone not switch to whole grains? (Cindy)