Dietary carbohydrate, glycemic index, and glycemic load and the risk of colorectal cancer in the BCDDP cohort.
BACKGROUND
There is considerable support for associations between insulin and IGF-I levels and colorectal cancer. Diet may relate to colorectal cancer through this mechanism, for example, diets high in glycemic index, glycemic load and/or carbohydrate are hypothesized to increase insulin load and the risk of insulin resistance, hyperinsulinemia. Case-control studies support this hypothesis, but prospective cohorts have had mixed results.


METHODS
In the Breast Cancer Detection Demonstration Project (BCDDP) follow-up cohort of 45,561 women, we used Cox proportional hazards regression to assess the distribution of 490 incident cases of colorectal cancer ascertained during 8.5 years of follow-up across quintiles of carbohydrate intake, glycemic index, and glycemic load. We also stratified by combined BMI and physical activity levels.


RESULTS
We found reductions in colorectal cancer risk for diets high in carbohydrate (RR for Q5 vs. Q1 = 0.70, 95% CI: 0.50-0.97) and glycemic index (0.75, 95% CI: 0.56-1.00), and no significant association for glycemic load (0.91, 95% CI: 0.70-1.20). Inverse associations were weakest in normal weight active persons. The inverse association for glycemic index was strongest for the portion from dairy food.


CONCLUSIONS
These results do not support an association between diets high in carbohydrate, glycemic index or glycemic load and colorectal cancer.
Strayer
Lori
L
Division of Epidemiology and Community Health, School of Public Health, University of Minnesota, 1300 South Second Street, Suite 300, Minneapolis, MN 55454, USA.
Jacobs
David R
DR
Schairer
Catherine
C
Schatzkin
Arthur
A
Flood
Andrew
A
D015331:Cohort Studies; D015179:Colorectal Neoplasms / Q000453:epidemiology*; D004040:Dietary Carbohydrates; D005260:Female; D038321:Glycemic Index; D006306:Health Surveys; D006801:Humans; D006946:Hyperinsulinism / Q000150:complications*; D015994:Incidence; D007333:Insulin Resistance; D008875:Middle Aged; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors; D011795:Surveys and Questionnaires; D014481:United States / Q000453:epidemiology
D004040:Dietary Carbohydrates