Kurihara N, Fan K, Thaler HT, Yang K, Lipkin M - 35566 N - J Med Food 2008 ; 11(2) : 1-6.

Effect of a Western-Style Diet Fortified with Increased Calcium and Vitamin D on Mammary Gland of C57Bl/6 Mice

We previously reported hyperproliferation and hyperplasia in C57Bl/6 mouse mammary gland after feeding a Western-style diet (WD); these findings decreased after supplementing WD with increased calcium and vitamin D(3). We now again fortified WD with increased calcium and vitamin D(3) from two sources: (1) a food source, calcium- and vitamin D(3)-enriched yogurt (WD(y) diet) or (2) adding calcium and vitamin D(3) directly to WD (WD(CaD) diet). After 6 months of feeding the number of mammary ducts was higher in mice consuming WD compared to WD(y) (216.0 vs. 202.7, P < .05) and WD(CaD) (216.0 vs. 194.9, P < .001). The percentage of small ducts increased in WD compared to AIN-76A controls (23.3% vs. 17.4%) but was lower in the WD(y) (17.1%) and WD(CaD) (14.8%) groups. WD mice had higher numbers of epithelial cells per duct than WD(y) (33.2 vs. 27.4, P < .001) and WD(CaD) (33.2 vs. 27.8, P < .001) mice, and AIN-76A-fed mice had higher numbers than WD(y) (31.1 vs. 27.4, P < .005) or WD(CaD) (31.1 vs. 27.8, P < .01) mice. Mitotic index was higher in WD than in WD(CaD) mice (0.0020 vs. 0.0009, P < .001). Thus, small mammary gland ductules and mitosis increased after feeding WD and decreased after supplementing the diets with increased calcium and vitamin D(3), administered either in a dairy food (yogurt) or directly as calcium carbonate plus vitamin D(3) in WD, suggesting further study of these nutrients for their possible relationship to breast cancer prevention.