Substitution of dietary macronutrients and their sources in association with breast cancer: results from a large-scale case-control study.

purposeTo evaluate the association between dietary replacement of carbohydrates, proteins, fats, and their sources and odds of developing breast cancer (BC).

methodsThis hospital-based large-scale case-control study recruited 464 women with confirmed BC within the past year and 500 apparently healthy controls matched in terms of age and residential place. Dietary data as well as other variables were collected by trained interviewers.

resultsAfter adjustment for all possible confounders, substituting every 50 kcal of energy from dietary carbohydrates for the same amount of energy from total fats was associated with lower odds for developing BC among all participants [odds ratio (OR) 0.97, 95% confidence interval (CI) 0.95-0.99] as well as premenopausal women (OR 0.96, 95% CI 0.94-0.99). Replacing protein intake with fat was associated with a higher likelihood of BC among postmenopausal women (OR 1.11, 95% CI 1.03-1.20). Replacement of carbohydrates with MUFAs might be associated with a decreased odds of BC and replacement of dietary carbohydrates with PUFAs might be associated with an increased odds of BC in all participants as well as postmenopausal women (P < 0.05). The same association was shown for protein only in postmenopausal women. Substituting MUFAs for saturated (SFAs) and PUFAs was associated with a significant decreased odds of BC in the whole population (P < 0.05). The same association was observed for replacing MUFAs for PUFAs in postmenopausal women.

conclusionSubstitution of dietary carbohydrates for total fats and PUFAs might reduce the odds of breast cancer. Also, substituting MUFAs for carbohydrates, SFAs and PUFAs might lower the disease risk. Future prospective investigations are highly recommended.