These recommendations are based upon studies suggesting that people who consume a diet rich in fiber from a variety of sources including, fruits, vegetables and whole grains, experience a lower risk of this malignancy. A recent study from the Harvard School of Public Health on a large group of American nurses was published in the prestigious New England Journal of Medicine and was widely quoted in the media as proving that no relationship exists between fiber intake and colon cancer risk. The over-simplification of this study and its results leads to confusion among the public. Media reporters and readers of articles and newspapers must recognize that single studies such as this are but one of a vast array of investigations that have been undertaken and published. Since each study may examine a different population group and the outcomes evaluated may be diverse, it is not surprising that results may vary in a field as complex as the role of dietary fiber in human health.
Epidemiologic studies use a very crude assessment of human dietary fiber intake.
These studies cannot take into account the fact that fiber from every fruit, vegetable, legume, or whole grain is different and has unique properties. Most epidemiologic studies treat fiber from all sources as being the same. Many of these investigations are not capable of assessing the specific roles that each type of fiber from different sources may have on colon cancer risk. We need more studies where groups of individuals at risk for colon cancer are provided different types of foods containing fiber in order to determine if a change in dietary fiber will reduce risk. Most importantly, the majority of recent news reports did not mention many other potential benefits of a diet rich in foods containing fiber.