Nelle, in fairness to vegans, calcium is available from plant based foods and eaten in the right quantities can be the equiv. Extra calcium intake (over RDI) have not shown any evidence of increasing bone density.

However, as a dairy product, it is a source of B12 - which is only available from animal sources (meat, dairy and eggs). B12 is one of the most crucial vitamins really as without it, the pathways between sections of your brain can break down. It is generally accepted that had homini not started eating animal products we would either have been wiped out a long time ago, or still be running around in loin cloths exclaiming "Ugg".

Seeing how I have become quite fond of my marbles - I will probably stick with my butter.