Association between diet quality and food waste in Canadian families: a cross-sectional study

Background: Higher diet quality has been associated with greater amounts of food waste among adults in the United States. This study aims to build on previous work by examining the association between diet quality and food waste, as assessed using detailed waste audits, among a sample of Canadian families.

Methods: This cross-sectional study used data from 85 Canadian families with young children. Parent and children diet quality was assessed using the Healthy Eating Index-2015 (HEI-2015), calculated from 3-day food records. Household food waste was measured using detailed waste audits conducted over multiple weeks and these data were used to calculate daily per capita food waste. Linear regression was used to explore the association between parent and child HEI-2015 scores and daily per capita total avoidable and unavoidable food waste, as well as daily per capita avoidable and unavoidable food waste in the following categories: 1) fruits and vegetables, 2) milk, cheese and eggs, 3) meat and fish, 4) breads and cereals, 5) fats and sugars.

Results: Parent HEI-2015 scores ranged from 37 to 92 (out of 100) and 81% of parents' diets scored in the "Needs Improvement (50-80)" category. Parent and child diet quality scores were significantly correlated (r=0.61; P<0.0001) and 82% of children's diets scored in the "Needs Improvement" category. On average, households produced 107 grams of avoidable food waste and 52 grams of unavoidable food waste per person per day. Fruits and vegetables were the highest contributor for both avoidable and unavoidable food waste. Both parent and child HEI-2015 scores were not significantly associated with total daily per capita avoidable or unavoidable food waste. However, parent HEI-2015 scores were positively associated with daily per capita avoidable fruit and vegetable waste (β= 1.05; 95%CI: 0.11, 1.99; P= 0.03) and daily per capita unavoidable fruit and vegetable waste (β= 0.60; 95%CI: 0.03, 1.17; P= 0.04), after adjusting for household income.

Conclusion: This is the first study to explore the association between diet quality and food waste using detailed waste audits. Future research should explore effective strategies towards improving diet quality while simultaneously reducing food waste, especially of fruits and vegetables.