Dietary intake of garlic and other Allium vegetables and breast cancer risk in a prospective study of postmenopausal women

Because garlic and its organosulfur compounds have been shown to inhibit the occurrence of mammary tumors in animal models, we sought to examine this association in the human population. During 15 years of follow-up, 34,388 postmenopausal women completing a food frequency questionnaire (FFQ) were followed for incident breast carcinoma. Supplemental data from a nested case-control study was analyzed to obtain consumption habits of other Allium vegetables not included in the FFQ. After 15 years, higher garlic intake was not found to be associated with lower breast cancer risk. A statistically significant inverse association was noted in the first 5 years (RR=0.71), but not in the second or third 5-year periods. In the nested case-control study, some inverse relationships were noted between the consumption of Allium vegetables and breast cancer, but overall do not show that a protective effect is afforded by more frequent intake of these herbs.