Dietary carbohydrates, fiber, and breast cancer risk in Chinese women.
BACKGROUND
Few studies have investigated the association of dietary carbohydrate and fiber intake with breast cancer risk in women in China, where carbohydrate intake is traditionally high.


OBJECTIVE
The objective was to prospectively evaluate the association of dietary carbohydrates, glycemic index, glycemic load, and dietary fiber with breast cancer risk and to determine whether the effect of these dietary intakes is modified by age and selected insulin- or estrogen-related risk factors.


METHODS
A total of 74,942 women aged 40-70 y were recruited into the Shanghai Women's Health Study, a population-based cohort study. Dietary intake was assessed by in-person interviews. A Cox proportional hazards regression model was used to evaluate associations.


RESULTS
During an average of 7.35 y of follow-up, 616 incident breast cancer cases were documented. A higher carbohydrate intake was associated with a higher risk of premenopausal breast cancer (P for trend = 0.002). Compared with the lowest quintile, the hazard ratios (and 95% CIs) were 1.47 (1.00, 2.32) and 2.01 (1.26, 3.19) for the fourth and fifth quintiles, respectively. A similar pattern was found for glycemic load. The association between carbohydrate intake and breast cancer was significantly modified by age; the increased breast cancer risk associated with carbohydrate intake was restricted to women who were younger than 50 y. No significant association of breast cancer risk with glycemic index or dietary fiber intake was found.


CONCLUSIONS
Our data suggest that a high carbohydrate intake and a diet with a high glycemic load may be associated with breast cancer risk in premenopausal women or women <50 y.
Wen
Wanqing
W
Vanderbilt Epidemiology Center, Vanderbilt University Medical Center, Nashville, TN 37203-1738, USA. wanqing.wen@vanderbilt.edu
Shu
Xiao Ou
XO
Li
Honglan
H
Yang
Gong
G
Ji
Bu-Tian
BT
Cai
Hui
H
Gao
Yu-Tang
YT
Zheng
Wei
W
D000328:Adult; D000367:Age Factors; D000368:Aged; D001943:Breast Neoplasms / Q000453:epidemiology*; D002681:China / Q000453:epidemiology; D015331:Cohort Studies; D016001:Confidence Intervals; D004040:Dietary Carbohydrates / Q000008:administration & dosage*; D004043:Dietary Fiber / Q000008:administration & dosage*; D004967:Estrogens / Q000378:metabolism; D005260:Female; D038321:Glycemic Index; D006801:Humans; D007328:Insulin / Q000097:blood; D008875:Middle Aged; D016017:Odds Ratio; D017697:Premenopause; D016016:Proportional Hazards Models; D011446:Prospective Studies; D018570:Risk Assessment; D012307:Risk Factors
D004040:Dietary Carbohydrates; D004043:Dietary Fiber; D004967:Estrogens; D007328:Insulin