Bone is often thought of as being relatively static once we reach adulthood. In reality, it is complex and dynamic, undergoing constant change throughout our lives. In a recent review, Brandon Batty and Massimo Bionaz, of the Oregon State University Department of Animal and Rangeland Sciences, examined bone structure, the physiological processes that affect bone formation and resorption, and the ways in which milk consumption affects bone density.
“Calcium is often seen as the most important component of milk for bone health, and adequate intake is recommended during adolescence to increase peak bone mass and help prevent osteoporosis later in life,” Batty said. “However, the diverse blend of nutrients in milk have been shown to increase bone health and development. Besides calcium, milk contains biologically relevant amounts of phosphorus, magnesium, protein, and vitamin D (due to fortification), which all contribute to bone growth and mineral accrual.”
In the review, Batty describes other components of milk that may promote bone density. The casein and whey proteins in milk are broken down into peptides with bioactive properties that promote bone formation and decrease bone resorption, as well as having antimicrobial, immunomodulatory, and antioxidant properties. Casein phosphopeptides, for example, may increase calcium absorption, directly affect bone cell growth, and result in greater deposition of calcium in bones. Lactoferrin can offset estrogen-dependent bone loss, increase bone formation, and reduce bone turnover rates.
However, further research into the direct effect of milk on the skeleton is needed, and there are important gaps in our knowledge to fill in the future.