Kentaro Murakami¹, Yoshihiro Miyake², Satoshi Sasaki¹, Keiko Tanaka², Yukihiro Ohya³, Yoshio Hirota⁴ and Osaka Maternal and Child Health study group⁵

¹Department of social and Preventive Epidemiology, school of Public Health, the University of Tokyo, Tokyo, Japan. ²Department of Public Health, Faculty of Medicine, Fukuoka University, Fukuoka, Japan. ³Division of Allergy, Department of Medical specialties, national Center for Child Health and Development, Tokyo, Japan. ⁴Department of Public Health, Osaka City University school of Medicine, Osaka, Japan. ⁵Other members of the Osaka Maternal and Child Health study group are listed in the Acknowledgments.

While several observational studies in European countries have shown that higher monetary diet cost is associated with healthier diets, information on the relationship of cost to diet quality in other countries is sparse, including Japan. This cross-sectional study examined the association between monetary diet cost and dietary intake in a group of pregnant Japanese women. Subjects were 596 pregnant Japanese housewives. Dietary intake was estimated using a validated, self-administered, comprehensive diet history questionnaire. Monetary diet cost was calculated using retail food prices. Values of monetary diet cost and nutrient and food intake were energy-adjusted using the density method. Monetary diet cost was associated positively with the intake of protein, total fat, saturated fatty acids, dietary fiber, cholesterol, sodium, potassium, calcium, magnesium, iron, vitamins A, D, E, C, and folate, and inversely with that of carbohydrate. For foods, cost was associated positively with the intake of potatoes, pulses and nuts, fish and shellfish, meat, dairy products, vegetables, and fruits, and inversely with that of rice and bread. No association was seen for noodles, confectioneries and sugars, fats and oils, or eggs. Cost was also associated inversely with dietary energy density. In conclusion, monetary diet cost was associated with not only favorable aspects of diet, including a higher intake of dietary fiber, key vitamins and minerals, fruits, and vegetables and lower dietary energy density, but also unfavorable aspects, including a higher intake of fat and sodium and lower intake of carbohydrate and rice, in a group of pregnant Japanese women.