Newswise — Why choose an apple over a bag of pretzels if they have roughly the same number of calories? It would be a simple matter of taste if calories were the only thing that counted. But nutrients count, too. For an equal number of calories, a person could also get fiber, vitamin C, and potassium by going with the apple. This example illustrates the concept of "nutrient density," which may be new to many people, although it's highlighted in the USDA 2005 Dietary Guidelines. Eileen Kennedy, DSc, RD, dean of the Friedman School of Nutrition Science and Policy at Tufts University, thinks it's important to help consumers understand the concept of nutrient density and how to categorize and choose foods based on nutrient density.
The Dietary Guidelines for Americans recommend consuming a variety of nutrient-dense foods and beverages as part of a healthful diet. "Let's give them the tools to make the choices we are recommending," urges Kennedy, who is also a former acting under secretary at the United States Department of Agriculture. Kennedy shares some ideas about communicating the concept of nutrient density to the public at an Experimental Biology symposium entitled "Cultural and Socioeconomic Challenges in Nutrition Education."
"We nutrition scientists describe foods as 'nutrient-dense' versus 'energy-dense,' but we need to be sure that the public knows what we mean," says Kennedy. Energy-dense foods provide more calories per unit of volume than less energy-dense foods. These calories, which come largely from refined sugars and fat, are sometimes called "empty calories." "In other words," says Kennedy, "energy-dense might sound healthy but it usually isn't."
Nutrient-dense foods, on the other hand, provide more nutrients and generally fewer calories per unit volume. "They're the foods that are loaded with the nutrients we need to thrive," says Kennedy. "Think about choosing a potato instead of potato chips, or a banana instead of a soda. Opt for a plate with lots of vegetables, and skip the dinner roll. Ignore the cake and go for the fruit."
"If Americans choose foods based on nutrient density," Kennedy says, "they will, essentially, be choosing foods based on quality." A food item that is nutrient-dense is generally a better choice than a less nutrient-dense food item with the same number of calories.
As a general rule, whole grain breads and cereals are more nutrient-dense than their "white" counterparts. Many fruits and vegetables are nutrient-dense snacks because, in addition to providing some basic carbohydrates, they are low in fat and are packed with fiber, vitamins, and minerals. Candies or sweetened beverages, in contrast, provide the carbohydrates (and maybe fats) without the other nutrients.
In a review article that appeared recently in the American Journal of Clinical Nutrition, Kennedy emphasizes the importance of lifestyle choices, particularly with respect to diet and physical activity. "The need to focus on prevention is clear," she wrote. Research has uncovered a range of diet-chronic disease links. With life expectancy increasing worldwide, Kennedy believes that more attention needs to be devoted to investigating how diet, physical activity, personal choice, and environmental constraints influence healthy aging.
"One way to refocus people on healthy food choices they need to make may be to promote a greater understanding of nutrient density," says Kennedy.
Kennedy ET. American Journal of Clinical Nutrition. 2006 (February); 83 (suppl):410S-414S. "Evidence for nutritional benefits in prolonging wellness."
The Gerald J. and Dorothy R. Friedman School of Nutrition Science and Policy at Tufts University is the only independent school of nutrition in the United States. The school's eight centers, which focus on questions relating to famine, hunger, poverty, and communications, are renowned for the application of scientific research to national and international policy. For two decades, the Jean Mayer USDA Human Nutrition Research Center on Aging at Tufts University has studied the relationship between good nutrition and good health in aging populations. Tufts research scientists work with federal agencies to establish the USDA Dietary Guidelines, the Dietary Reference Intakes, and other significant public policies.