The term "nutrient density" has become common in discussions about the values of different foods in a healthy diet. However, no official standards have been established to evaluate a food's nutrient density. According to the American Dietetic Association, or ADA, establishing common standards of nutrient density would make it easier for you to make decisions about which foods you should emphasize in your diet to maintain a healthy weight and avoid chronic disease.
Significance
In its "Dietary Guidelines for Americans 2005," the U.S. Department of Agriculture, or USDA, emphasizes the need for Americans to include more nutrient-dense foods in their diet. The USDA defines nutrient density in relation to a food's caloric content. Foods that are high in vitamins, minerals and other nutrients but low in calories qualify as nutrient-dense foods. Spinach, carrots, apples, oranges and dried beans are examples of foods that offer high amounts of nutrients relative to their caloric content. By comparison, foods with a low nutrient density are high in calories and fat but offer relatively few essential nutrients. Doughnuts, regular sodas, potato chips, candy and other processed snack foods and desserts have a low nutrient density, according to the USDA's definition.
Energy Density
The concept of nutrient density often intersects with the concept of energy density, or the relationship between the calories in a food and its volume. Many nutrient-dense foods, such as fruits and vegetables, are high in volume -- mostly consisting of water and fiber -- but low to moderate in calories, or energy. In an article published in the Oct. 2005 issue of the "American Journal of Clinical Nutrition," Adam Drewnowski says that a definition of nutrient density based on calories alone may not encompass foods that are high in calories, fat, vitamins, minerals and other nutrients. Avocados, nuts and olive oil provide examples of foods that are dense in both nutrients and energy, or calories. When considering the nutritional value of foods, Drewnowski states, it's important not to equate nutrient density with low energy density.
Health Concerns
The USDA's focus on nutrient density reflects its concern about the rising rates of obesity and chronic disease in the American population. In its "Dietary Guidelines for Americans 2005," the USDA encourages the consumption of more foods that are high in nutrients -- especially calcium, potassium, magnesium, fiber and vitamins A, C and E -- and low in calories. Popular definitions of nutrient density tend to exclude foods based on their content of saturated fat, cholesterol, added sugar or sodium -- substances that have been linked to higher rates of obesity, type 2 diabetes and cardiovascular disease. According to the ADA, this approach to nutrient density could lead to a separation of foods into "good" and "bad" foods, which may be counterproductive in planning a balanced diet.
Expanded Definition
Over the years, a number of health organizations and nutritionists have proposed standards for defining nutrient density. However, the ADA says that no consensus has been reached about which of these methods offers the best approach for evaluating a food's nutritional content. According to the ADA, the USDA's definition of nutrient density should be used to compare the nutritional content of foods within the same food group and to emphasize the degrees of value that each food provides. A baked potato, for example, may provide roughly the same minerals, vitamins, carbohydrates and fiber as a serving of french fries, but because a baked potato has fewer calories and less fat, the baked potato is a more nutrient-dense food and would represent a healthier choice when planning your meal.
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