When you think of adult drinks, milk may not be the first thing that comes to mind. However, when it comes to bone health, qualitative research shows that most adults associate consumption of milk and cheese with a bone health benefit, and name calcium and vitamin D as top nutrients. Baby Boomer and older consumers were more likely than younger generations to say that milk provides a bone health benefit. The older adults surveyed did not associate milk with helping to build muscle to the same degree as did younger adults.
But what we are learning – and what all adults should know — is that maintaining both bone and skeletal muscle as they age is important for helping to reduce the incidence of fragility fractures later.
Recently a group of recognized bone experts from Switzerland, France, and North America collaborated on a paper to examine interactions between four nutrients – calcium, inorganic phosphate, vitamin D, and protein – and their role in preserving bone and skeletal muscle with age.
Dairy nutrients interact to help maintain bone and muscle
These researchers recognized that people eat foods, rather than nutrients – and that milk and the foods made from milk contain appreciable amounts of calcium, phosphorus, and protein. In addition, many countries such as the U.S. and Canada, fortify milk as well as some yogurts and cheeses with vitamin D. These are key nutrients adults need as they get older.
The authors show how all four of these nutrients, when in adequate supply, interact through several physiological mechanisms to maintain bone health during aging. They also show how the interaction between dietary protein and physical activity (including weight-bearing and resistance exercise) helps preserve skeletal muscle mass and function to help prevent sarcopenia. And preventing sarcopenia may ultimately help reduce risk of falls and fracture.
Why protein is required for bone formation
As health professionals, you are probably most familiar with how protein helps preserve muscle – but may be less familiar with how protein helps preserve bone. I found it interesting to learn why protein is required for bone formation and the nutrient interactions and steps involved:
First, consumption of protein can increase the circulating level of IGF-1 (insulin-like growth factor-1), which enhances the renal production of 1,25(OH)D, which in turn stimulates the intestinal absorption of both calcium and inorganic phosphorus. IGF-1 also increases phosphorus retention.
Thus, dietary protein has a positive influence on bone mineralization. In addition, consumption of adequate amounts of high quality protein, such as found in milk, along with regular resistance exercise, helps older people preserve skeletal muscle and function.
Under nutrition is common, particularly in the elderly. A national nutrition survey shows that consumption of milk, yogurt, and cheese declines among older adults. While all adults consume only about half the recommended three servings of dairy foods per day, adults over age 50 consume the least (1.36 servings/day).
As you counsel adults or talk to friends or family members, you can use this information to show that milk is indeed an adult drink, and why it should be an important part of a healthy lifestyle.