A comparison between acidic and basic protein fractions from whey or milk for reduction of bone loss in the ovariectomised rat

The ability of whey acidic protein fractions to protect against bone loss due to ovariectomy (OVX) in the mature female rat was investigated. The bone bioactivity of these acidic protein fractions, isolated from both mineral acid whey protein concentrate (WPC) and rennet WPC, was compared with that of basic protein fractions isolated from both milk and rennet WPC. Fifty 6-month old rats that had been ovariectomised at 5.5 months were randomised into five groups of ten each. One group remained the OVX control while four groups were each fed one of the acidic or basic protein fractions as 0.3% (w/w) of the diet, for 4 months. Ten sham-operated rats served as a second control group. Sequential measurements of bone mineral density of the spine and femur indicated that the acidic protein fraction prepared from mineral acid WPC reduced bone loss due to OVX, maintaining bone density above OVX levels at week 16 of feeding. Biomechanical data indicated that both acidic fractions tended to increase bone stiffness, and hence resistance against breaking.