A woman at risk for osteoporosis is told by her doctor to get 1,200-1,500 milligrams of calcium every day. But when she looks at the Nutrition Facts panel on a carton of yogurt or a jug of milk, she finds that calcium is only listed by “Percent Daily Value” (%DV).

How does she convert that to milligrams?

If she’s like most of us…she can’t. And neither can her doctor.

Those were among the findings of research conducted by Laura A. Peracchio, professor of marketing at the University of Wisconsin-Milwaukee (UWM), and Lauren Block, professor of marketing at Baruch College (CUNY). The results were so compelling that the U.S. Food and Drug Administration added information to its Web site on how to translate %DV to milligrams.

The research, which involved three separate studies and a follow-up, is discussed in “The Calcium Quandary: How Consumers Use Nutrition Labels for Daily Diet,” published in the Journal of Public Policy and Marketing. Peracchio and Block found that:

· In Study 1, only two of 37 respondents correctly translated the calcium information on a carton of yogurt from %DV to milligrams.

· In Study 2, when 20 physicians were shown the same label, only six gave the right answer in milligrams. (Asked how the calculation was done, one physician who gave an incorrect answer replied: “I have no idea. I made it up.”) Yet most doctors dispense calcium recommendations to their patients in milligrams.