Nutrition labels on food packages in the United States can be difficult to understand, and Canada's labels suffer the same flaws, an American researcher says. 

When researchers at Vanderbilt University Medical Centre in Nashville surveyed about 200 subjects from a wide socioeconomic background, they found about one in five people studied could figure out the number of carbohydrates in two slices of bread.

Consumers often have a hard time understanding what a serving size is.
(Courtesy of Health Canada)

About 32 per cent of those surveyed correctly calculated the number of carbohydrates in a bottle of pop containing 2½ servings, the researchers report in the November issue of the American Journal of Preventive Medicine.

Consumers often have a hard time understanding what a serving size is and then applying it, leading them to grossly overestimate or underestimate how much they have consumed, said Dr. Russell Rothman, the study's lead author.

"The first thing people run into trouble with is that the serving size is four crackers," Rothman said. "So people will get confused if they only eat two crackers or if they eat six crackers."

The problems found with the American labels would be the same with Canada's black-and-white nutrition labels, Rothman said.

In Canada, labels have been required on pre-packaged foods since last December, although smaller manufacturers have another year to comply.

People make errors in calculating portion sizes, or they get confused by the wide range of information on the labels, the study's authors said. 

Olivia Camp of Halifax says nutrition labels help her understand what she's eating, but sometimes there's some guess work involved.

"The grams, I can't register in my mind … what that means," said Camp.

Label lessons

The researchers suggest governments could simplify labels to make them more effective, for example by basing the grams of fat or calorie content on an entire bag of chips or can of pop that people are likely to consume, rather than a smaller serving size.

Health Canada is rolling out educational material to make people more label savvy, said Mary Bush, the department's director general of nutrition policy and promotion.

Health Canada has an interactive website to help people understand nutrition labels.

Nutritionist Rosie Schwartz suggested people practise decoding the labels by comparing two similar products. For example, the sodium content in a pre-prepared cup of noodles may be much higher than a package of uncooked noodles.  

"Sodium free" means the product contains fewer than five milligrams of sodium, while "sodium reduced" just means it has less sodium than another similar product it is being compared to. Likewise, "calorie reduced" means a food contains 25 per cent fewer calories than the product it is being compared to, but does not necessarily mean it is low in calories, Schwartz said.