Whey protein suppresses the osteoclast-mediated bone resorption and osteoclast cell formation

Abstract

Effects of whey protein on bone resorption and osteoclastic cell formation were evaluated. In the pre-existed and newly formed osteoclast , in bone resorption methods using an unfractionated bone cell culturing system, whey protein suppressed the area of pits formed by osteoclasts. In the osteoclastic cell formation method using the hemopoietic blast cell culturing system, whey protein also suppressed osteoclastic cell formation. These activities were resistant to heat when the protein was treated at 75–90°C for 10 min. Heat-treated whey protein was first fractionated on a Mono S column, and the active fraction (basic protein fraction) was then applied to Superose 12. The molecular weights of the active components were approximately 23 000 and 10 000 Da, as determined by gel filtration. The inner solution of an everted gut-sac incubated in a solution of intact basic protein (BP), pepsin-digested BP or pepsin/pancreatin-digested BP also suppressed osteoclast-mediated bone resorption. Thus, these active components can possibly be absorbed or transported by the intestines. These results showed that whey protein contains an active component that suppresses osteoclast-mediated bone resorption and osteoclastic cell formation.