Early news reports about an AICR funded study published in the August 1 issue of the journal Cancer Epidemiology, Biomarkers & Prevention contain imprecise language that may only serve to confuse the public.
In the CEBP study, Mexican researchers compared the self-reported diets of 475 breast cancer patients to the reported diets of 1391 healthy women who were similar in age, weight and other factors. Researchers found that subjects whose reported diets contained the most carbohydrates were more likely to have breast cancer than subjects who ate the least carbohydrates.
Two important points need to be made:
- You cannot, on the basis of this or any single study, draw conclusions about carbohydrates and their effect on cancer risk. To warrant dietary change, scientific findings must first be reviewed, considered against the bulk of previous evidence and replicated by different researchers using studies of different types.
- You cannot make generalizations about “carbohydrates,” because the category contains an enormous variety of foods that have vastly different nutritional profiles and vastly different effects on the body.
Carbohydrates are the dietary mainstay of most cultures around the world. The category encompasses unprocessed, fiber-rich foods such as vegetables and fruits as well as highly processed chips, cookies and cupcakes. Thus, it is unlikely that any generalizations about “carbohydrates” will stand up to scrutiny.
Some news reports on the CEBP study have noted that the main carbohydrates consumed by women in the study were highly processed – corn tortillas, chips, white bread, and soft drinks.
What has been largely overlooked, however, is that the researchers also analyzed how consumption of insoluble fiber – found in vegetables, fruits, whole grains and beans – affected cancer incidence. Women in the study who ate the most insoluble fiber had lower breast cancer risk.
The distinction between refined and unrefined carbs is shaping up to be an important one, and one that will figure largely in future studies of diet’s link to cancer and other diseases. We at AICR believe that every effort must be made to keep that distinction clear in the public’s mind.
The American Institute for Cancer Research is one of the nation’s largest cancer charities, focusing exclusively on the link between diet and cancer.