2 ways of knowing fibre won't prevent colon cancer

The idea that a high-fibre diet prevents colon cancer dates back to the early 1970s but research has since debunked this theory. Here are two ways scientists got to the bottom of the faulty fibre-cancer connection.

• Scientists began to study fibre's potential by comparing the diets of healthy people with the diets of people who had developed colon cancer. A survey of 13 such studies found that people who ate the most fibre seemed to slash their risk of colon cancer by nearly 50 percent
• This type of study has a few built-in catches, however. For instance, many people change their diets over the years, and when a researcher asks about your diet, it can be awfully hard to remember what you ate a decade ago

When scientists put fibre to some tougher tests, they chewed up its reputation as a colon protector.

• In one study sponsored by the National Cancer Institute, researchers randomly assigned 2,079 male and female colon cancer survivors to eat either a high-fibre meal plan or to stick with their usual diets. Four years later, almost exactly the same percentage of people in both groups had had recurrences of colon cancer
• Another large study using fibre supplements yielded similar results
• In the final blow, scientists reviewed 13 studies in which participants were asked about their current diets, then were followed for up to 20 years. The investigators determined that fibre had no benefit

That doesn't mean there aren't reasons to eat more fibre; there are plenty of them.

Most people eat too little fibre. The Institute of Medicine recommends consuming 14 grams of fibre for every 1,000 calories in your diet. For the average person, that means 25 to 30 grams of fibre daily. A high-fibre diet can keep your digestive system running smoothly, but it won't keep colon cancer at bay.