Monetary value of self-reported diets and associations with sociodemographic characteristics and dietary intake among Japanese adults: analysis of nationally representative surveys.

OBJECTIVE
To examine the relationships of monetary value of diets with sociodemographic and lifestyle characteristics and dietary intake among Japanese adults.

DESIGN
Cross-sectional study based on two nationally representative surveys: the Comprehensive Survey of Living Conditions and the National Health and Nutrition Survey, 2013. Dietary intake was assessed by a 1 d semi-weighed household dietary record with information on individual proportion of intakes. Diet cost was estimated by linking dietary data with retail food prices. A wide variety of sociodemographic and lifestyle variables were obtained from the two surveys.

SETTING
A random sample of nationally representative households in Japan.

SUBJECTS
Japanese adults aged 20 years or older (n 4658).

RESULTS
Lower energy-adjusted diet cost (Japanese yen/4184 kJ) was significantly associated with being younger, having a lower education, less equivalent monthly household expenditure, large household size, less physical activity and living in rented houses. Lower diet cost was associated with a lower intake of pulses, vegetables, fruits, fish, meat and dairy products, and a higher intake of grain, eggs, and fats and oils. At the nutrient level, lower diet cost was associated with a lower intake of protein, alcohol, dietary fibre, cholesterol and all vitamins and minerals examined, and a higher intake of carbohydrate. Diet cost was inversely associated with dietary energy density.

CONCLUSION
These data suggest that certain low socio-economic subgroups in Japan consume diets of lower monetary value, resulting in a lower quality of food and nutrient intake pattern except for lower sodium, cholesterol and alcohol consumption.