Controversies surrounding milk consumption and health were highlighted in a unique three-day conference, held October 23-25, 2006, in Boston, MA. The multidisciplinary event brought together dairy scientists, epidemiologists, analytic chemists, geneticists, physicians, and physiologists in an effort to integrate the evidence underlying claims of health benefits or health risks associated with milk consumption.
The meeting concluded that the hormonal content of dairy milk is, at present, incompletely defined, and that addressing this gap in knowledge should be a research priority. There was interest in evidence presented by Dr. Sjurdur Olsen, who reported that a study of 101,042 Danish women revealed an association between higher milk consumption by pregnant women and the birth weight of their children. This was supported by evidence presented by Dr. Kristine Koski showing that Canadian women who restrict milk consumption during pregnancy have lower birth-weight infants. Although the mechanisms underlying these associations are unknown, there was speculation that insulin-like growth factor I (IGF-I) may be involved. Several research groups have observed that milk consumption is associated with modest elevations of this growth-promoting hormone in blood levels.
Milk contains a complex mixture of hormones and micronutrients. Although milk consumption increases breast cancer risk in some laboratory experiments, a review of available epidemiologic evidence revealed no strong associations between milk consumption during adult life and risk of breast cancer. Data suggest that consuming several glasses of milk per day may slightly decrease colon cancer risk, while increasing risk of fatal prostate cancer and possibly ovarian cancer. More information is needed to allow precise estimates of various disease endpoints in adulthood according to level of milk consumption at different ages.
Although drinking milk is often recommended to improve bone health, there is evidence that milk consumption in adulthood does not influence fracture risk.
There was general agreement that milk is an excellent food for undernourished populations and is appropriate for infants. Well-nourished adults do not require high levels of dairy consumption, and the optimum level of intake remains uncertain.
Proceedings of the workshop, organized by the Harvard Center for Cancer Prevention and the McGill
University Cancer Prevention Centre, will be published. For further information, contact us here