A new study has reported that greater pork and beef consumption during adolescence may account for a substantial portion of the increase in breast density (and the associated increase in risk of breast cancer) among Chinese immigrants as they become acculturated in the U.S.

The study was designed to investigate the influence of adolescent diet, level of physical activity, and body size on breast density in adulthood among U.S. Chinese immigrant women. The study included 201 women recruited in 2002 and 2003 from Philadelphia breast cancer screening programs. Mammographic images were divided into four categories ranging from entirely fatty to extremely dense. Questionnaires were used to assess diet and physical activity during adolescence (ages 12 to 17), weight and height at age 10, and weight at age 18. Degree of acculturation (adoption of the cultural patterns of the general U.S. population) was also assessed.

Higher adult breast density was found to be significantly associated with adolescent red meat intake but not with any of the other adolescent factors studied. Women in the highest third of red meat intake were three times as likely to have dense breasts as those in the lowest third. Degree of acculturation in adulthood was also associated with increased breast density. Adjusting for adolescent red meat intake reduced this association from 2.5 to 1.9 times for the highest compared to the lowest level of acculturation. The authors conclude that greater red meat intake during adolescence may have increased adult breast density and thereby partly accounted for the strong association between acculturation and breast density in this sample of immigrant Chinese women. If confirmed by further study, dietary prevention efforts for breast cancer should be considered earlier in life.