Intersections of Educational Attainment, Indigenous Identity, and Race/Ethnicity Best Predicted Diet Quality Among Adults in Canada: A Conditional Random Forests Analysis

Abstract

Background

Although it is well-known that diet quality varies according to multiple dimensions of socioeconomic position (SEP), much remains unknown about how these dimensions together shape diet quality. Given that diet quality associated with 1 SEP dimension (eg, income) can systematically differ across another dimension (eg, race and ethnicity), it is necessary to investigate diet quality across SEP intersections.

Objectives

The aim of this study was to identify SEP intersections that best predicted lower and higher diet quality among adults in Canada.

Design

Population-based data were from the cross-sectional 2015 Canadian Community Health Survey–Nutrition. Data were collected by interviewers who visited selected dwellings to collect household information and administer a general health questionnaire and a 24-hour dietary recall.

Participants/Setting

Data from 13 617 adults aged 18 years and older living in Canada’s 10 provinces.

Main Outcome Measures

Twenty-four–hour dietary recall data were used to assess diet quality based on the Healthy Eating Index-2015 (HEI-2015) score (range, 0 to 100).

Statistical Analyses Performed

Conditional random forests, a supervised machine-learning technique, were used to identify 4 of 12 SEP indicators that best individually predicted HEI-2015 scores. The resulting 4 most important predictors were used to predict diet quality using all possible 2-way intersections.

Results

The 4 most important intersectional predictors of HEI-2015 scores based on conditional random forest variable importance measures were (1) educational attainment and Indigenous identity and race/ethnicity, (2) educational attainment and household food insecurity, (3) educational attainment and sex/gender, and (4) household food insecurity and sex/gender. Among these 4 SEP intersections, individuals without a high school diploma living in a severely food-insecure household had the lowest (55.7), and individuals without a high school diploma identifying as Middle Eastern had the highest (64.5) predicted HEI-2015 scores.

Conclusions

The SEP intersection defined by educational attainment and Indigenous identity and race/ethnicity was the most important predictor of diet quality among adults in Canada.