Study Links High Carbohydrate Intake with Breast Cancer.
For years we have blamed high fat intake for causing many chronic diseases. For example high fat diets were considered a major risk factor for breast cancer and patients were instructed to stick to extremely low fat diets. Now the trend seems to be shifting to blaming high carbohydrate diets for all of our ills. It may be that neither is really the true culprit. Both fats and simple carbohydrates contain relatively empty calories, devoid of the vitamin, mineral, and phytochemicals which protect against disease. It may end up that simply the more empty calories consumed the greater the risk for disease. Until we get to that point expect to see more studies appearing that blame our woes on excess carbs.
CUERNAVACA, Mexico--High carbohydrate diets were positively linked to increased incidence of breast cancer, according to a study published in the August issue of Cancer Epidemiology Biomarkers & Prevention (13, 8:1283-89, 2004) (www.cebp.aacrjournals.org).
The study conducted by the Instito Nacional de Salud Publica was a population-based case-controlled study involving 475 women aged 20 to 75 years with breast cancer (identified through six Mexico City hospitals) and a comparison group of 1,391 healthy women from the Mexico City population.
Researchers administered a questionnaire relating to sociodemographic variables and potential risk factors for breast cancer including reproductive and lactation history and diet. The sample population showed a total energy intake comprised of 57 percent carbohydrates, 27.6 percent fat and 15.4 percent protein.
After adjusting for total energy intake and all potential confounding variables such as age, social economic status, family history of breast cancer and parity, the risk of breast cancer was 2.2 times higher in women in the highest quartile of total carbohydrate intake when compared to women in the lowest quartile. The association was present in both premenopausal and postmenopausal women.
Among carbohydrate components, the strongest associations were observed for sucrose and fructose. No association was observed with total fat intake; however, polyunsaturated fat was inversely associated with risk of breast cancer, particularly among postmenopausal women.
The study also found dietary fiber intake may modulate the absorption of carbohydrates and can influence the glycemic response. The strength of the association between sucrose intake and risk of breast cancer was lower among women in the highest tertile of insoluble fiber intake when compared with women in the lowest tertile of insoluble fiber intake. The relative risk of breast cancer in the highest quartile of sucrose intake was 2.37 among women who consumed low levels of insoluble fibers (<22 g/d) and was 1.07 among women who consumed high levels of insoluble fibers (>22 g/d). Similar results were observed for fructose and glucose intakes.
The researchers concluded in this population a high percentage of calories from carbohydrate--but not from fat--was associated with increased breast cancer risk. This relationship deserves further investigation, the researchers noted, particularly in populations highly susceptible to insulin resistance.
Epidemiology Biomarkers & Prevention Vol. 13, 1283-1289,
Carbohydrates and the Risk of Breast Cancer among Mexican Women
Isabelle Romieu 1 , Eduardo Lazcano-Ponce 1 , Luisa Maria Sanchez-Zamorano 1 , Walter Willett 2 and Mauricio Hernandez-Avila 1
1 Instituto Nacional de Salud Publica, Cuernavaca, Morelos, Mexico and 2 Departments of Nutrition and Epidemiology, Harvard School of Public Health and Channing Laboratory, Department of Medicine, Brigham and Women's Hospital and Harvard Medical School, Boston, Massachusetts
Requests for reprints: Isabelle Romieu, Instituto Nacional de Salud Publica, Avenida Universidad 655, Colonia Santa Maria Ahuacatitlan, Cuernavaca , Morelos 62508 , Mexico . Phone: 52-777-101-2935; Fax: 52-777-311-1148; E-mail: email@example.com
Objective: High carbohydrate intake has been hypothesized to be a risk factor for breast cancer, possibly mediated by elevated levels of free insulin, estrogens, and insulin-like growth factor-1. Therefore, we conducted a population-based case-control study among a Mexican population characterized by relatively low fat and high carbohydrate intakes. Methods: Women ages 20 to 75 years, identified through six hospitals in Mexico City ( n = 475), were interviewed to obtain data relating to diet (using a food frequency questionnaire) and breast cancer risk factors. Controls ( n = 1,391) were selected from the Mexico City population using a national sampling frame. Results: Carbohydrate intake was positively associated with breast cancer risk. Compared with women in the lowest quartile of total carbohydrate intake, the relative risk of breast cancer for women in the highest quartile was 2.22 [95% confidence interval (95% CI) 1.63-3.04], adjusting for total energy and potential confounding variables ( P for trend < 0.0001). This association was present in premenopausal and postmenopausal women (for highest versus lowest quartile, odds ratio 2.31, 95% CI 1.36-3.91 in premenopausal women and odds ratio 2.22, 95% CI 1.49-3.30 in postmenopausal women). Among carbohydrate components, the strongest associations were observed for sucrose and fructose. No association was observed with total fat intake. Discussion: In this population, a high percentage of calories from carbohydrate, but not from fat, was associated with increased breast cancer risk. This relation deserves to be investigated further, particularly in populations highly susceptible to insulin resistance.