The researchers behind the study, from the University of Washington’s Center for Public Health Nutrition and the Nutritional Sciences Program, tracked the pricing of nutrient-dense foods, such as vegetables and whole grain fortified cereals, and nutrient-poor foods, such as those that are high in fat, sugar and refined grains, from 2004 to 2008. Over the four-year period, they found that the supermarket price of the top 20 percent most nutrient-dense foods increased 29.2 percent, while those in the least nutrient-dense 20 percent rose by 16.1 percent.
These findings could mean there are added barriers for Americans when it comes to following dietary guidance, they said. And this could prove to be particularly significant at a time when many US consumers are dealing with lost or diminished incomes.
“There is a growing price disparity between nutrient-dense foods and less nutritious options,” the authors wrote. “Cost may pose a barrier to the adoption of healthier diets and so limit the impact of dietary guidance.”
Measuring nutritional quality
The researchers measured nutritional quality by comparing energy density in kilocalories per gram, and nutrient density, using two separate frameworks that assess nutrients per calorie. One of these frameworks is based on 14 nutrients to encourage, such as protein, fiber, monounsaturated fatty acids, and a range of vitamins and minerals, and the other is based on nine nutrients to encourage, as well as three nutrients to limit: saturated fat, added sugars, and sodium.
The researchers found that the average price of the top quintile of foods for nutrient-density using these indices cost $27.20 per 1000 calories, while the bottom quintile for nutrient density cost an average $3.32 per 1000 calories.
Economic constraints
The 2005 Dietary Guidelines for Americans – the guidelines currently in use, until the 2010 guidelines are published later this year – recommend that consumers should increase their consumption of nutrient-dense foods across all food groups, but the authors suggest that rising prices could make this goal unrealistic for some.
“The sharp price increase observed for nutrient rich foods relative to other less nutritious foods indicates that economic constraints may pose a barrier to a healthful diet,” they wrote. “Lost or diminished incomes combined with rising food prices could have adverse consequences for consumers’ diet quality, and as a result, their nutritional status and health.”
The researchers added that nutrient profiling could help to emphasize the most affordable and acceptable sources of nutrients in the food supply, irrespective of food group.
Source: Food Policy
(2010), doi:10.1016/j.foodpol.2010.06.004
“The rising disparity in the price of healthful foods: 2004–2008”
Authors: Pablo Monsivais, Julia Mclain, Adam Drewnowski