Viscous and nonviscous fibres, nonabsorbable and low glycaemic index carbohydrates, blood lipids and coronary heart disease

Dietary glycemic load and colorectal cancer risk

BACKGROUND

Insulin and insulin-like growth factors can stimulate proliferation of colorectal cells. High intake of refined carbohydrates and markers of insulin resistance are associated with colorectal cancer. To test the insulin/colon cancer hypothesis, we determined whether the dietary glycemic index and the glycemic load are associated with colorectal cancer risk.

DESIGN

A case-control study on colorectal cancer conducted in Italy. Cases included 1125 men and 828 women with histologically confirmed incident cancer of the colon or rectum. Controls were 2073 men and 2081 women hospitalized for acute conditions. We calculated average daily dietary glycemic index and glycemic load, and fiber intake from a validated food frequency questionnaire.

RESULTS

Direct associations with colorectal cancer risk emerged for glycemic index (odds ratio (OR) in highest vs. lowest quintile = 1.7; 95% confidence interval (CI): 1.4-2.0) and glycemic load (OR = 1.8; 95% CI: 1.5-2.2), after allowance for sociodemographic factors, physical activity, number of daily meals, and intakes of fiber, alcohol and energy. ORs were more elevated for cancer of the colon than rectum. Overweight and low intake of fiber from vegetables and fruit appeared to amplify the adverse consequences of high glycemic load.

CONCLUSIONS

The positive associations of glycemic index and load with colorectal cancer suggest a detrimental role of refined carbohydrates in the etiology of the disease.

Functional foods and cardiovascular disease

Functional foods are foods that, by virtue of physiologically active food components, provide health benefits beyond basic nutrition. Many functional foods have been found to be potentially beneficial in the prevention and treatment of cardiovascular disease, the leading cause of mortality in the United States. These foods include soybeans, oats, psyllium, flaxseed, garlic, tea, fish, grapes, nuts, and stanol- and sterol ester enhanced margarine. When eaten in adequate amounts on a consistent basis, these foods may aid in decreasing the risk of cardiovascular disease by several potential mechanisms: lowering blood lipid levels, improving arterial compliance, reducing low-density lipoprotein oxidation, decreasing plaque formation, scavenging free radicals, and inhibiting platelet aggregation.