Most doctors tell patients suffering from osteoporosis to increase their intake of calcium, but the scientific literature shows that calcium pills do not help to prevent or treat bone fractures. This implies that you should get your calcium from foods rich in that mineral. Dairy products are among the richest sources of dietary calcium, but studies have shown that drinking milk does not appear to reduce bone fractures (British Journal of Nutrition, May 28, 2017;117(10):1432-1438). This month, a review of the scientific literature found 18 articles following 363,557 participants for 3 to 23 years showing that yogurt and cheese, but not milk or cream, are associated with decreased risk for hip fractures (BMC Public Health, February 02, 2018). People who ate a lot of yogurt or cheese had a 25 to 32 percent lower risk of hip fractures than those who ate little or no cheese or yogurt. This new research shows that eating cheese or yogurt is associated with reduced risk for hip fractures, not that it prevents fractures.
How Cheese and Yogurt Differ from Milk
Nobody knows how cheese or yogurt may help to prevent bone fractures, but we have some clues. Milk contains a double sugar called lactose that is made up of two sugars, glucose and galactose, bound together. The bacteria that ferment milk to make cheese or yogurt break down lactose into its two single sugars, then galactose is converted into glucose which is consumed by the bacteria during the fermentation process. The difference between milk and fermented dairy products is that milk contains galactose while cheese and yogurt contain little or no galactose.
Galactose can cause inflammation that damages cells. When you are infected by germs, your immune cells and proteins try to kill the invading germs, but as soon as the attacking germs are gone, your immunity is supposed to dampen. However, if your immunity stays active, it causes inflammation and uses the same cells and proteins to attack you and damage your own cells. Galactose has been shown to be the most pro-inflammatory sugar of the four sugars that can pass from the intestines into the bloodstream (Cytokine, Sept 2014;69(1):150-153).
People who drink milk have increased urine levels of 8-iso-PGF2a (a marker of oxidative stress) and serum interleukin 6, a marker of inflammation (Biogerontology, 2004;5:317-25). Having high blood levels of inflammatory markers is associated with increased risk for bone fractures, particularly of the hip (J Bone Miner Res, 2014;29(9):2057-2064). People with multiple markers for inflammation have more than three times the risk of hip fractures (J Bone Miner Res, 2007;22(7):1088-1095). Having blood markers of inflammation is associated with increased osteoclast cell activity that breaks down and weakens bones. An anti-inflammatory diet, based on fruits and vegetables and limiting added sugars, red meat and processed meats, appears to reduce inflammation and helps to prevent bone fractures (J Bone Miner Res, May 2017;32 (5):1136–1146). Other studies also suggest that galactose in milk can promote oxidative stress and inflammation, which in turn increases risk for bone fractures (BMJ, 2014;349:g6015).
What Causes Osteoporosis?
Nobody really knows what causes osteoporosis, but it is associated with:
• increasing age,
• malnutrition (Curr Osteoporos Rep, 2009;7(4):111–7),
• vitamin D deficiency and low exposure to sunlight (Scand J Public Health, 2014;42(2):201–6),
• lack of physical activity,
• smoking (PLoS One, 2016;11(12):e0168990), and
• excessive intake of alcohol (Am J Epidemiol, 1999;149(11):993–1001).
Even though many studies associate lack of calcium with increased risk for osteoporosis (Osteoporos Int, 2011;22(11):2769–88), no good studies have shown that calcium pills prevent fractures. This new study suggests that cheese and yogurt, but not milk, may help to prevent osteoporosis.