This week I discovered how painful it can be to change a habit.  Not because it means admitting I was doing the wrong thing, but because it means analyzing how feeble my reasons were for the habit in the first place. Ever since I started practice I’ve been recommending calcium supplements to post-menopausal women.  Why?  Mostly out of habit.  There’s not a shred of evidence that calcium supplements prevent fractures, but some suggestion that they may help bone density.  But what’s the harm?  Ca...