Tehran University Medical Journal

Background: Breast cancer is the most common cancer among females in the world. Identifying the nutrients that modify the risk of the disease is one of the key strategies for improving the quality of life and reducing treatment costs. Epidemiological studies support the role of macronutrients and vitamins involved in one carbon metabolism in the etiology of the disease. This study aimed in investigation of the relationship between the intake of macronutrients and vitamins involved in one carbon metabolism with breast cancer risk.

Methods: This case-control hospital base study was conducted at Shohada Hospital, Tehran from April to February 2015. Demographic data, physical activity level and nutrients’ intake from diet and supplements were collected through interview from 151 cases and 154 controls. Dietary intake was assessed by a valid and reliable 168-item semi-quantitative food frequency questionnaire. Then intake of macronutrients and B vitamins was assessed by Nutritionist 4 software (First Databank Inc., CA, USA). Comparing categorical variables between the two groups was done by Chi-squared test and the relationship between intake of studied nutrients and risk of breast cancer was determined using logistic regression test.

Results: There were no difference in age, menarche age, menopause age, body mass index (BMI), number of live births between two groups. But the difference in physical activity, energy intake, marital status, educational level, occupation, oral contraceptives use was significant (P< 0.001). After modifying the effects of confounding variables, the risk of breast cancer was significantly lower in the highest intake quartile category relative to the lowest quartile category for total protein, total fiber, intake of vitamins B₂, B₆, B₁₂ and folate (P_trend< 0.001). Before modifying the effects of confounding variables, the risk of breast cancer was significantly higher in the highest intake quartile category relative to the lowest quartile category for carbohydrate and fat; but after modifying the effects of confounding variables, results were not significant.