Submitted to: American Journal of Clinical Nutrition
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/8/2009
Publication Date: 2/18/2009
Publication URL: http://www.ajcn.org/cgi/reprint/89/4/1220
Citation: Townsend, M., Grant, A., Monsivais, P., Keim, N.L., Drewnowski, A. 2009. Lower-energy-density diets of low-income women in California are associated with higher energy-adjusted diet costs. American Journal of Clinical Nutrition. 89:1220-1226, 2009. Interpretive Summary: Obesity rates are higher for adults in the lower-income brackets in the United States. Energy density is a term used to describe diets that are concentrated in calories per weight of the foods; this feature of the diet has been linked to overeating and obesity: as energy density increases, overeating and obesity increases. We investigated the relationship between the cost of diets of low-income women residing in California and the quality of their diets, with emphasis on energy density of the diets. We found that as energy density of the diet increased, the cost of the diet decreased. The women who paid the least for their diets were consuming diets with more energy density, higher fat content, less fiber, and lower amounts of vitamin A and C, indicating that the overall quality of their diets was inferior to the diets of women whose diets cost more. These findings are relevant for the USDA’s food assistance and education programs. Strategies for improving diet quality without increasing costs should be included in the respective curricula of USDA’s primary prevention education interventions.
Technical Abstract: Low-energy-density diets have been shown to be associated with higher diet quality and with better health outcomes. However, such diets have also been associated with higher diet costs. This study examined the impact of dietary energy density on energy-adjusted diet costs among a sample of low-income women. Energy and nutrient intakes for 112 women aged 18-45y living in California were obtained using a food frequency instrument. Dietary energy density (MJ/kg or kcal/g) and energy-adjusted diet costs ($/10MJ or $/2,000 kcal) were calculated for each study participant using local food prices. Tertile splits of energy density and energy cost were analyzed using one-way ANOVA. Mean daily energy intake excluding all beverages was 7.1 MJ (1699 kcal) and mean dietary energy density was 6.5 kJ/kg (1.54 kcal/g). Lower dietary energy density was associated with significantly higher intakes of dietary fiber (p=.004), vitamin A (p<0.0001), and vitamin C (p<0.0001) and with significantly lower intakes of total fat (p=.003) and saturated fat (p<0.001). Higher diet cost was associated with significantly lower dietary energy density (p<0.0001), total fat (p=0.024) and saturated fat (p=0.025) and with significantly higher intakes of vitamin A (p=0.003) and C (p<0.0001). Each additional dollar in estimated diet costs was associated with a drop in energy density of 0.94 MJ/kg (0.225 kcal/g). The finding that higher-quality diets were more costly for these low-income women has implications for the USDA’s food assistance and education programs. Strategies for improving diet quality without increasing costs should be included in the respective curricula of USDA’s primary prevention education interventions. Policy interventions may be required to allow low-income families in the United States to improve the quality of their diets given their food budget constraints.