High-Glycemic foods & Colon Cancer


Diarmid Logan


High-Glycemic foods & Colon Cancer

February 5, 2004

By Dyan Fresta

A diet rich in foods that trigger a quick and drastic jump in blood sugar levels may lead to
colon cancer.

Researchers at Harvard and UCLA find that the future risk of colorectal cancers is nearly three
times higher in women who eat the most high glycemic-loaded foods compared with those who eat lesser
amounts of these foods.

High-Glycemic foods include breads, pastas, pancakes and other carbs made from refined "white"
grains, as well as other processed or sugary foods like cakes, cookies and snacks.

Researchers say they find a very straightforward and clear association between high-glycemic foods
and colorectal cancers. It's apparently because they seem to trigger a greater tendency toward
insulin resistance and may be conducive to tumor growth.

The study is published in the Feb 4th issue of the Journal of the National Cancer Institute.








Dietary Glycemic Load and Risk of Colorectal Cancer in the Women's Health Study

Susan Higginbotham, Zuo-Feng Zhang, I-Min Lee, Nancy R. Cook, Edward Giovannucci, Julie E.
Buring, Simin Liu

Affiliations of authors: Department of Epidemiology, University of California at Los Angeles, Los
Angeles (SH, ZFZ); Division of Preventive Medicine, Harvard Medical School and Brigham and Women's
Hospital, Boston, MA (IML, NRC, JEB, SL); Departments of Epidemiology (IML, EG, JEB, SL) and
Nutrition (EG), Harvard School of Public Health, Boston.

Correspondence to: Simin Liu, MD, ScD, Division of Preventive Medicine, Harvard Medical School and
Brigham and Women's Hospital, 900 Commonwealth Ave., Boston, MA 02215 (e-mail:
[email protected])

Although diet is believed to influence colorectal cancer risk, the long-term effects of a diet with
a high glycemic load are unclear. The growing recognition that colorectal cancer may be promoted by
hyperinsulinemia and insulin resistance suggests that a diet inducing high blood glucose levels and
an elevated insulin response may contribute to a metabolic environment conducive to tumor growth. We
prospectively followed a cohort of 38 451 women for an average of 7.9 years and identified 174 with
incident colorectal cancer. We used baseline dietary intake measurements, assessed with a
semiquantitative food-frequency questionnaire, to examine the associations of dietary glycemic load,
overall dietary glycemic index, carbohydrate, fiber, nonfiber carbohydrate, sucrose, and fructose
with the subsequent development of colorectal cancer. Cox proportional hazards models were used to
estimate relative risks (RRs). Dietary glycemic load was statistically significantly associated with
an increased risk of colorectal cancer (adjusted RR = 2.85, 95% confidence interval [CI] =
1.40 to 5.80, comparing extreme quintiles of dietary glycemic load; Ptrend = .004) and was
associated, although not statistically significantly, with overall glycemic index (corresponding
RR = 1.71, 95% CI = 0.98 to 2.98; Ptrend = .04). Total carbohydrate (adjusted RR
= 2.41, 95% CI = 1.10 to 5.27, comparing extreme quintiles of
carbohydrate; Ptrend = .02), nonfiber carbohydrate (corresponding RR =
2.60, 95% CI = 1.22 to 5.54; Ptrend = .02), and fructose (corresponding RR = 2.09, 95% CI = 1.13 to
3.87; Ptrend = .08) were also statistically significantly associated with increased risk. Thus,
our data indicate that a diet with a high dietary glycemic load may increase the risk of
colorectal cancer in women.