Less-energy-dense diets of low-income women in California are associated with higher energy-adjusted diet costs

Background: US-based studies are needed to estimate the relation, if any, between diet quality and estimated diet costs. Objective: We hypothesized that lower cost diets among low-income women in California would be energy dense but nutrient poor. Design: Energy and nutrient intakes for 112 women aged 18-45 y living in California were obtained with a food-frequency instrument. Dietary energy density (in MJ/kg or kcal/g) and energy-adjusted diet costs (in $/10 MJ or $/2000 kcal) were calculated with local food prices. Tertile splits of energy density and energy cost were analyzed with one-factor analysis of variance. Results: 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 = 0.004), vitamin A (P < 0.001), and vitamin C (P < 0.001) and with significantly lower intakes of total fat (P = 0.003) and saturated fat (P < 0.001). Higher diet cost was associated with significantly lower dietary energy density (P < 0.001), total fat (P = 0.024), and saturated fat (P = 0.025) and with significantly higher intakes of vitamins A (P 0.003) and C (P, 0.001). Each additional dollar in estimated diet costs was associated with a drop in energy density of 0.94 MJ/kg (0.225 kcal/g). Conclusions: The finding that higher quality diets were more costly for these low-income women has implications for the food assistance and education programs of the US Department of Agriculture. 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. Am J Clin Nutr 2009; 89: 1220-6.