Do you understand the nutrition labels on food products regarding the recommended daily input of vitamins and minerals?

Three studies (published in the Journal of Public Policy and Marketing) by researchers at the University of Wisconsin-Milwaukee had consumers and doctors look at nutrition facts labels and decipher them.

The researchers concluded that food labels showing calcium as a percentage of daily intake confused consumers seeking to meet their recommended quotas. Both they and even some physicians had trouble interpreting the information so they know how much calcium is actually contained in food products.

The apparent problem arises because the standard unit of measurement used in the recommended daily intake of calcium is milligrams, but some food labels list it as a percentage of the recommended daily intake.

For calcium, the average recommended daily intake (RDI) of calcium is 1,000 mg a day. So one would think it would be easy to convert the value by simply adding a zero to the percentage
to get the number of milligrams. For example, if the label said 20%, that would mean 200 mg.

In one of the three studies, only two of 37 consumers correctly translated the calcium information on a carton of yogurt from percentage of daily intake to milligrams.

And in a similar study of physicians, only 6 of 20 doctors surveyed gave the right answer in milligrams.

In the third study, 41 pregnant or breastfeeding women were told to take 1,200 to 1,500 mg of calcium by their doctor. One-half of the women were provided with a calcium fact sheet explaining how to convert the percentage of daily intake into milligrams.

The University of Wisconsin-Milwaukee research found that those women who received the fact sheet took the proper amount of calcium - but that those who did not receive the explanatory fact sheet took less calcium than they were told to take.

The researchers believe these results show that the current labelling system leads to an under consumption of calcium among consumers.