OBJECTIVETo examine the effects of the whey basic protein on bone metabolism of Sprague-Dawley (SD) rats and healthy mid-aged women.

METHODSForty-four female SD rats were randomized by weight into four groups of eleven rats each and fed 10 mg x kg BW(-1) x d(-1), 20 mg x kg BW(-1) x d(-1), 30 mg x kg BW(-1) x d(-1) of whey basic protein and control diet was given respectively by intragastrically injection for 90 days. Bone mineral density of femur was measured by dual-energy X-ray absorptiometry in vitro. Sixty-three health women [(37.9 +/- 4.3) years old] were randomly assigned to treatment with placebo, 30 mg whey basic protein per day or 60 mg whey basic protein per day for 24 weeks. The bone mineral density (BMD) of the lumbar vertebrae L2-LA, femoral neck and right calcaneus of each subject were measured by dual-energy X-ray absorptiometry (DXA) at 0 and the 24th week of treatment. Serum bone specific alkaline phosphatase and N-telopeptide (NTX) were measured at 0 and the 14th week.

RESULTSThe mean BMD value of the distal end of the femur in 10 mg x kg BW(-1) x d(-1) whey basic protein group was significantly higher than that of the control group at the end of the trail. But after treatment by doses of whey basic protein used in the study, there were no differences between the control group and others groups on bone mineral density in the human trail.

CONCLUSIONWhey basic protein should enhance the bone mineral density of the rats' femur and no obvious effect was detected in the human trail.