Retorts

More Figures Required

Dr Caroline C. Howarth takes J. A. Grant-Mackie to task for criticising research supporting guidelines for calcium intake [Viewpoint, Nov]. She quotes, as an example justifying the guidelines, that in a group of 3,270 old women, supplementing their calcium intake reduced risk of fracture by more than 30%.

I would like to know how many women had their diet supplemented, and from what base. I would like to know what was the risk of fracture which was reduced by more than 30%. Were there three fractures in the control group, two in the supplemented group, or 1635 and 1090?

As it is reported, I cannot judge the merit of the example quoted by Howarth. More meaningful reporting would have added to my assessment of the credibility of her example and general thesis.

Pat Palmer, Christchurch