What Do Australians Eat? A Systematic Review of Dietary Patterns and Adverse Health Outcomes

Abstract

Context: A suboptimal diet is a leading factor in the current burden of chronic diseases. In Australia, dietary factors contribute to one-fifth of the chronic disease burden. Understanding the dietary patterns of Australian adults and summarizing their effects on chronic conditions are imperative for improving interventions targeting dietary behaviors.

Objective: This systematic review aims to summarize the dietary patterns of Australian adults derived using a posteriori and hybrid analysis methods and their associations with adverse health outcomes.

Data sources: Six databases were first searched in December 2020 and updated in August 2023.

Data extraction: Cardiometabolic health, cardiovascular mortality, cancer, pregnancy-related metabolic conditions (gestational diabetes mellitus [GDM] or hypertensive disorders during pregnancy [HDP]), mental health, and cognitive function were the main health outcomes.

Data analysis: Dietary patterns from each study were classified as either healthy or unhealthy. A narrative synthesis was used to describe the association of dietary patterns with adverse health outcomes in longitudinal studies. Fifty-nine observational studies (31 cross-sectional, 3 case-control, 22 longitudinal, and 3 combining both cross-sectional and longitudinal designs) were included, involving a total of 362 263 participants aged 18 years and older.

Conclusion: Higher adherence to a healthy dietary pattern (characterized by higher consumption of dark-yellow, green leafy, cruciferous vegetables and fruits, nuts, whole grains, tomatoes, fish, and low-fat dairy) is associated with improved cardiometabolic risk factors, reduced risk of GDM and HDP, better mental health, and improved pregnancy outcomes. On the other hand, an unhealthy dietary pattern (characterized by a higher intake of processed and red meat, takeaway foods, white bread, high-fat dairy, potatoes, discretionary fat, sweet snacks, soft drinks, fat spreads, jam, and Vegemite) is linked to increased cardiometabolic risks. Overall, while healthy dietary patterns are associated with a reduced risk of several physical and mental health outcomes, unhealthy dietary patterns are linked to an increased risk in Australian adults.

Systematic review registration: PROSPERO registration no. CRD42023452960.

Keywords: Australia; chronic diseases; health outcomes; healthy dietary pattern; unhealthy dietary pattern.

Figure 1.

Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) Flow Diagram Showing Study Search and Inclusion for Systematic Reviews. Abbreviations: CA, cluster analysis; PCA, principal components analysis

Figure 2.

Names of Dietary Patterns Reported in the Original Studies. The font size of the words or phrases indicates the relative quantity of these dietary patterns in the included studies

Figure 3.

Summary of Association of Healthy Dietary Patterns With (A) Cardiometabolic Diseases and Risk Factors; (B) GDM and HDP; (C) Cancer; and (D) Other Health Outcomes. Studies reported in different estimands (RRs and ORs). Cardiometabolic diseases—estimates were from 3 studies with different dietary patterns or outcomes. Cardiometabolic risk factors—estimates were from 3 studies with different dietary patterns or outcomes. GDM and HDP—estimates were pooled from 2 studies with different dietary patterns or outcomes. Abbreviations: ARMD, age-related macular degeneration; CVD, cardiovascular disease; GDM, gestational diabetes mellitus; HDL, high-density lipoprotein; HDP, hypertensive disorder during pregnancy; IHD, ischemic heart disease; LBW, low birth weight; LDL, low-density lipoprotein; MS, multiple sclerosis; OR, odds ratio; PCA, principal components analysis; RR, risk ratio; TG, triglyceride; TT, treelet transform; VMS, vasomotor menopausal symptom

Figure 4.

Summary of Association of Unhealthy Dietary Patterns With (A) Cardiometabolic Diseases and Risk Factors; (B) GDM and HDP; (C) Cancer; and (D) Other Health Outcomes. [Studies reported in different estimands (RRs and ORs). Cardiometabolic diseases—estimates were from 3 studies with different dietary patterns or outcomes. Cardiometabolic risk factors—estimates were from 3 studies with different dietary patterns or outcomes. GDM and HDP—estimates were pooled from 2 studies with different dietary patterns or outcomes. Abbreviations: ARMD, age-related macular degeneration; CVD, cardiovascular disease; GDM, gestational diabetes mellitus; HDL, high-density lipoprotein; HDP, hypertensive disorder during pregnancy; IHD, ischemic heart disease; LBW, low birth weight; LDL, low-density lipoprotein; MS, multiple sclerosis; PCA, principal components analysis; TG, triglyceride; TT, treelet transform; VMS, vasomotor menopausal symptom