Those who were taught how to translate the information consumed more. Researchers believe the same is true for other beneficial nutrients.
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 problem
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.
The central question of the research, Peracchio and Block write, is: “How do consumers make food consumption decisions when product information falls short of providing the nutritional knowledge needed for personal health consumption goals"”
And the answer
The answer is found in Study 3, which involved 41 women who were pregnant or breast-feeding. All had been told by their doctors or had read independently that they needed 1,200-1,500 milligrams of calcium a day.
Half of the women were given a one-page calcium fact sheet including the formula for converting %DV to milligrams. The formula is simple – %DV is based on the average recommended calcium intake of 1,000 milligrams daily. To convert %DV to milligrams, just add “0” to the percentage on the label. For example, a carton of milk delivering 30% DV contains 300 milligrams of calcium.
The women who were given the fact sheet consumed significantly more average daily calcium (a mean of 1,429.78 milligrams) than women who were not given the fact sheet (a mean of 988.24 milligrams).
Current labeling leads to under-consumption of calcium, the research showed. The women who were not given the fact sheet may have consumed close to 100%DV of calcium daily, but it fell short of the 120-150% DV they really needed.