The association between diet price and diet quality among Australian adults participating in the 2020 International Food Policy Study

This cross-sectional study examined the association between diet price and diet quality in a national sample of Australian adults (n=1,956). Diet recall data from the 2020 International Food Policy Study (IFPS) was linked with a national food and beverage price dataset. Daily diet price was calculated by summing the median non-promotional prices of all foods and beverages recorded in diet recall data, priced per gram (or millilitre) and adjusted for edible portions. Diet quality was determined using the Australian Dietary Guideline Index 2013 (scored out of 115). Linear regression models tested the association between the diet price (per dollar, and per ten-dollar increments) and diet quality, adjusted for education, age and sex. A positive association was observed, where diet quality increased by 0.09 units (95% CI, 0.05-0.14) for every $AU 1 increase in diet price. Daily diet price explained approximately 8% of the variation in diet quality across the sample (R 2 =0.08). When categorised in ten-dollar increments, participants with diet prices <$AU 10/day had a lower mean diet quality score (51.96) compared to all other diet price categories, 5-6 points lower than those whose diet was >$30/day. Diet price was a modest, yet significant determinant of diet quality for Australian adults in 2020. Additional analyses are needed to investigate these associations during recent food price inflation. As diet quality appears to be lowest for people who spend the least on food, government action to increase priority communities’ food budgets may help improve the nutritional quality of population diets.