Using cultured bone cells known as osteocytes in which oxidative stress was induced by serum deprivation, the administration of blueberry juice containing various amounts of polyphenols resulted in prevention of oxidative stress-induced apoptosis (a type of programmed cell death) and a reversal of factors involved in the activation of osteoclasts (which break down bone) and bone resorption. Juice containing the lowest concentrations of polyphenols decreased reactive oxygen species by approximately 25% after four hours, while the highest concentration was associated with a 50% decline compared to untreated serum-starved cells. When the effects of blueberry juice and a powdered blueberry extract that contained the same amount of soluble polyphenols were compared, no significant difference was observed. It was discovered that blueberry juice and blueberry extract increased the expression of sirtuin type 1 (SIRT1), which is involved in apoptosis regulation.
The research team also found that the juice prevented oxidative-stress induced cell cytotoxicity in bone marrow mesenchymal stromal cells, which are considered to be important for cell therapy in bone disorders because of their ability to differentiate into various tissues, including bone.
“The results of this study demonstrate, for the first time, in osteocytes, cells in close contact with blood capillaries and considered the major regulators of bone remodeling, a significant relationship between the antioxidant activity of blueberries and molecular events related to apoptosis and expression of osteoclastogenic factors induced by oxidative stress, write Vladana Domazetovic and colleagues at the University of Florence.
“Beneficial anabolic effects of blueberries in bone tissue have been reported in animal studies, which suggest blueberries to be a useful supplement for the prevention and/or management of osteoporosis and the osteogenic process,” they conclude.