If you're more likely to understand how to program a VCR than to figure out the nutritional content of the foods you eat, you're not alone. In my private practice, I continually have to explain nutrition labels to clients.

According to U.S. research published this month, difficulty in translating the nutrition facts box on packaged foods can result in shortchanging your body out of vitamins and minerals, especially calcium.

If you're at risk of osteoporosis, then you've probably been told to consume 1,500 milligrams of calcium a day. Yet, figuring out how much calcium is in a serving of yogurt or cheese is challenging because the mineral is listed only by a percentage of "daily value." It appears that most people - and their doctors - can't convert that into milligrams of calcium.

Researchers from the University of Wisconsin-Milwaukee found that only two out of 37 respondents correctly translated the calcium information from a carton of yogurt to milligrams. When 20 physicians were shown the same label, only six gave the right answer.

In another study, 41 women who were pregnant or breastfeeding were told to consume 1,200 to 1,500 milligrams of calcium a day. Half the women were given a fact sheet on calcium that included the formula for converting percentage of daily value to milligrams.

The women who were given the fact sheet consumed significantly more calcium each day compared with those who received no instructions for reading labels (1,430 milligrams compared with 988 milligrams).

A percentage of daily value is confusing because most of us don't know what the "daily value" is for each nutrient. The measurement is based on the average recommended intake for a 2000-calorie diet. For calcium, percentage of daily value is based on 1,100 milligrams. That means that a 175-gram carton of yogurt delivering 25-per-cent daily value contains 275 milligrams of calcium (0.25 multiplied by 1,100).

But you don't have to take a calculator grocery shopping. You can get a quick estimate by simply adding a 0 to the percentage on the label. Although this formula slightly underestimates calcium content, it's easy to calculate.

The recent research isn't the first to report consumer confusion over food labels. A 2006 study of educated adults found that 75 per cent had trouble understanding nutrition labels and many lacked the math skills needed to decipher them.

According to the Canadian Council of Food and Nutrition, 75 per cent of Canadians use food labels at least sometimes and one in four always consults the label when deciding what to eat.

In an effort to make food labels easier to understand, Health Canada introduced mandatory nutrition labelling for most prepackaged foods in December 2005. (Small food companies have until the end of this year to post nutrition labels on their products.) Compared with old labels, the revised nutrition facts box is larger and easier to find, and provides more information.

Yet for many people, nutrition labels are still difficult to interpret.

Check serving size

The only way to know how much fat, sugar, sodium or fibre you're consuming is to compare the serving size listed on the label with the amount you actually eat. Don't assume that one package of food - a bottle of fruit juice, a frozen dinner, or even a bagel - is one serving. Figure out how much you eat and then do the math.

Use percentage

of daily values

These percentages are listed for fat, saturated and trans fat, sodium, carbohydrate, fibre, vitamins A and C, calcium and iron. Instead of trying to remember the amount each figure is based on, follow the "5 and 25 rule."

If a label says one serving of a food supplies 5 per cent or less of the daily value, that's good for things you want to curtail, such as saturated and trans fat, sugars and sodium.

But it's not ideal for fibre, calcium, iron, and vitamins A and C. On the other hand, if one serving of a food supplies 25 per cent or more for vitamins A and C, calcium, iron or fibre, then it's an excellent source of these nutrients.

For saturated and trans fat, the percentage of daily value is based on 20 grams. Foods low in these fats will have a percentage of daily value of 10 per cent or less.

For sodium, the percentage of daily value is based on set at 2,400 milligrams, the daily amount you should not exceed. Foods low in sodium will have a percentage of daily value of 5 per cent or less.

Get the whole picture

Just because a food carries a "trans-fat free" claim doesn't mean it's good for you. Foods that are "trans-fat free" must contain less than 0.2 grams of trans fat and no more than 2 grams of trans and saturated fat combined in a serving. But that doesn't mean they're low in total fat. And they may deliver a hefty dose of sodium.

"Calorie-reduced" foods may also contain too much fat, sugar or sodium. You need to read the entire label to know what you're eating.

Leslie Beck, a Toronto-based

dietitian at the Medcan Clinic,

is on CTV's Canada AM every Wednesday. Visit her website

at lesliebeck.com.

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These tips will help you navigate the nutrition facts box (taken from a box of All-Bran cereal bars).

*Check the serving size. The only way to know how much you're consuming is to compare the serving size with the amount you actually eat.

*Follow the '5 and 25 rule' for the percentage of daily values. Look for foods that have 5 per cent or less of what you'd like to curtail, or 25 per cent or more of the nutrients you want.

*Foods low in saturated and trans fat have a value of 10 per cent or less.

*Foods low in sodium have a value of 5 per cent or less.

TRISH McALASTER / THE GLOBE AND MAIL

SOURCE: LESLIEBECK.COM

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