Preventing the formation of aberrant crypt foci in 1,2-dimethylhydrazine-treated mice by dietary milk and maitake mushroom (Grifola frondosa)

Abstract

 To suppress the incidence of colorectal cancer (CRC) that has been recently increasing in East Asian countries, effective measures such as chemoprevention are required. Epidemiological and cohort studies suggested the importance of diets containing calcium, dietary fiber, and vitamin D in suppressing the risk of CRC. In this study, we investigated tumor-suppressive activities in dietary milk, maitake mushroom (Grifola frondosa) which is an edible mushroom rich in vitamin D, and their combinations by evaluating aberrant crypt foci (ACF) development in the colon of the mice treated with 1,2-dimethylhydrazine (DMH). AIN-76 standard diet (approximately 4 g of calcium per kg diet) as a control and AIN-76 supplemented with either 10% milk (10 MK), 10% maitake mushroom (10 MM), 5% milk＋5% maitake mushroom (5 Mix), or 10% milk＋10% maitake mushroom (10 Mix), were fed to mice for 11 weeks. Supplementation with milk, maitake mushroom, and their combination significantly suppressed (p<0.05) DMH-induced ACF formation compared to the control (ACF numbers, 10 MK>5 Mix>10 MM>10 Mix). Cecal pH was significantly lower (p<0.05) in the experimental groups of 10 MM and 10 Mix than that of control, indicating higher short chain fatty acid production by intestinal bacteria. These results suggest that daily intake of milk, maitake mushroom, and their combination represses CRC via repression of ACF formation. In addition to high absorption and bioavailability of milk calcium, the beneficial change in intestinal flora might result in suppression of ACF formation. The synergistic effects of simultaneous daily intake of milk and maitake mushroom on the suppression of ACF formation require further investigation.