In the present proposal a method is described that may enable studying the effect of nutrition on bone calcium turnover far more accurate, within a shorter time frame and therefore less intensive for the volunteers in clinical studies as compared to presently existing methods. This method will enable screening for promising food concepts for combating osteoporosis within a relatively short time. Recent developments show that use of the nuclide 41Calcium (41Ca) and measurement by accelerator mass spectrometry (AMS) has great potential in measuring effects on bone level within a relatively short period of time. When introducing a diet change (intervention) the bone metabolism of calcium may change resulting in a changed 41Ca-signal in the urine. So far a few medication studies with osteoporotic volunteers have been performed and it appears that this ultrahigh sensitive technique may also be applicable for nutrition studies in healthy volunteers.