Abstract
Recent studies indicate that lifestyle factors in early life affect breast cancer risk. We therefore explored the association of high consumption of meat, milk, and whole grain products in adolescence and midlife, on breast cancer risk. We used data from the population based AGES-Reykjavik cohort (2002–2006), where 3,326 women with a mean age of 77 years (SD 6.0) participated. For food items and principal component derived dietary patterns we used Cox proportional models to calculate multivariate hazard ratios (HR) with 95% confidence intervals (95% CI). During a mean follow-up of 8.8 years, 97 women were diagnosed with breast cancer. For both adolescence and midlife, daily consumption of rye bread was positively associated with breast cancer (HR 1.7, 95% CI 1.1–2.6 and HR 1.8, 95% CI 1.1–2.9, respectively). In contrast, persistent high consumption of oatmeal was negatively associated with breast cancer (0.4, 95% CI 0.2–0.9). No association was found for other food items or dietary patterns that included rye bread. High rye bread consumption in adolescence and midlife may increase risk of late-life breast cancer whilst persistent consumption of oatmeal may reduce the risk.
Highlights
During adolescence the female mammary tissue undergoes extensive modeling or re-modeling
We found a positive association between high consumption of rye bread in adolescence and breast cancer risk
We further divided rye bread consumption into three groups and explored the association with breast cancer risk, where we found a significant trend across the groups, hazard ratios (HR) 1.0 and HR 1.7, respectively (Ptrend = 0.043)
Summary
During adolescence the female mammary tissue undergoes extensive modeling or re-modeling. Researchers have hypothesized that breast tissue may be susceptible for initiation of breast tumors during this period [1, 2]. There is increasing evidence on the importance of adult midlife diet and risk of breast cancer [3] while available studies on the impact of diet during adolescence on breast cancer risk are scarce and somewhat inconsistent [4]. Studying early life diet can be challenging due to potential misclassification bias, the need for a long follow-. Rye bread intake in adolescence and midlife and risk of breast cancer
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