NHMRC is reviewing the 2013 Australian Dietary Guidelines (the 2013 Guidelines).

Scoping activities to refine the scope of the revision have been completed. A broad list of topic areas and research questions have been prioritised based on their public health impact and the likelihood that the evidence-base has changed enough since the release of the 2013 Guidelines to change the recommendations.

Diet is a huge topic, with a large volume of evidence underpinning the Guidelines. To make efficient use of the limited review resources, recent, high-quality published systematic reviews will be used where available to update the 2013 Guidelines. A limited number of evidence reviews may be commissioned where important evidence gaps are identified. Scoping and mapping work to identify suitable (current, comprehensive and methodologically robust) systematic reviews is currently taking place.

More information about the prioritisation process and research question development is available in the Prioritisation Process Report.

Priority research questions

During 2020 and 2021, NHMRC undertook initial scoping activities. These activities were intentionally broad, involving web searches, literature database searches and media platform searches. Direct input was sought from stakeholders through surveys and targeted consultation on various aspects of the 2013 Guidelines and companion resources.

The initial scoping activities identified a broad list of research topic areas of interest. This list was considered by the Dietary Guidelines Expert Committee (Expert Committee) who participated in a series of surveys and discussions to agree on a shortlist of topic areas. The tables below provide more detail about these topics. In summary the priority topics are:

  • dietary patterns (combinations and amounts of foods regularly consumed)
  • nutritional needs across the life course
  • protein-rich foods (meats and poultry, fish, eggs, tofu, nuts and seeds and legumes/beans)
  • (ultra) processed foods.

Sustainable diets (accessible, affordable and equitable diets with low environmental impacts) were also identified as a very high priority. Sustainability will be addressed via a separate process.

A literature search is underway to help NHMRC identify relevant systematic reviews or identify gaps in the evidence base for the priority questions where new evidence reviews may need to be commissioned.

To supplement the literature search, a public call for systematic reviews was open from 1 August to 11 September 2023. Submissions were anonymous.

Only systematic reviews addressing the priority research questions and meeting the eligibility criteria listed below are being considered at this stage.

How lower priority questions will be managed

Pragmatic considerations partly contributed to decisions about priority including whether a topic could be partially or indirectly addressed by an alternative research question of higher priority.

The topic areas prioritised for review do not necessarily reflect the priority of the recommendations to be updated. There will be topics that are critical for national dietary guideline recommendations which have not been identified during this scoping and evidence mapping exercise as being the highest priority for review.

Topics identified as ‘moderate’ or ‘low’ priority during this phase but still considered to be critical for dietary guideline recommendations will be considered using:

  • existing evidence from the 2013 Guidelines where the evidence is not likely to have changed enough to change the recommendations since their release
  • systematic reviews published by recognised international groups.

Eligibility criteria

Systematic reviews will be screened against eligibility criteria before being considered for inclusion in the revision. Eligible citations will be checked to ensure that the studies have not been redacted. Redacted studies will be excluded.

Eligibility criteria for existing systematic reviews considered in the evidence review process

To be considered suitable for use, systematic reviews identified must:

  • be a peer-reviewed systematic review (with or without a meta-analysis) of primary studies in humans
  • address, or partially address, one or more of the priority research questions and its associated populations, interventions/exposures, comparators and outcomes
  • have been published in the last 5 years (2018–2023), with literature searches conducted no earlier than 1 January 2017
  • be published in English (not translated)
  • meet the below methodological criteria:
    • published a protocol before starting the review which clearly described the types of studies eligible for inclusion in the review
    • searched at least two scientific databases, including PubMed (Medline) and/or Embase
    • documented search strategies and performed full text screening by at least two people
    • clearly documented the number of studies identified and included/excluded at each stage
    • assessed and reported on quality or risk of bias of included studies, including identifying the tool used to assess each study design.

The following will be excluded:

  • systematic reviews of nutritional supplements or nutrient-specific interventions. Nutritional (or dietary) supplements are products added to the diet, usually in the form of a pill, capsule, tablet, powder or liquid. They contain one or more dietary ingredients such as vitamins, minerals, herbs, amino acids and enzymes.
  • systematic reviews addressing micronutrients
  • systematic reviews of systematic reviews (also called umbrella reviews or overviews).

Eligible systematic reviews will be mapped against the research questions to allow the Expert Committee to consider options for addressing each priority research question and identify gaps in the underlying evidence base, that may be targeted by a commissioned review. The outcomes of the scoping and mapping work will be published on the NHMRC website when available.

Broad research questions for highest priority topics

To be considered for use in the review, a systematic review must relate to one of the priority research questions. The prioritised research questions can be categorised according to two broad types of question:

  • Diet and health outcomes: research questions that explore the relationship between different diets or eating behaviours and health outcomes; or
  • Contextual factors: research questions that explore the relationship between contextual factors (e.g. food security) and achievement of diets consistent with guideline recommendations.

Each research question comprises a population of interest, an intervention /exposure of interest, a comparator of interest, and one or more outcomes of interest. Collectively, these parameters are known as the ‘PI/ECO’ criteria.

The PI/ECO criteria for research questions focused on diet and health outcomes are listed at Table 1. PI/ECO criteria for research questions exploring contextual factors are listed at Table 2.

To be eligible for consideration, systematic reviews must address the PI/ECO criteria listed in Table 1 or Table 2, including:

  • one of the priority Intervention/Exposure and Comparison pairs (e.g. high versus low intake of plant foods) OR contextual factors (e.g. food security) AND
  • at least one of the associated Populations (e.g. children) AND
  • at least one of the in-scope Outcomes (e.g. child development).
Table 1. PI/ECO criteria for questions focused on diet/eating behaviour and health outcomes
Populations
At least one of the following:		 Outcomes
At least one of the following outcomes:		 Intervention / Exposure and Comparison Pair
At least one of the following:

Includes:

  • Adults (including older adults, and those at risk of chronic disease)

AND/OR

  • Pregnant & breastfeeding people

AND/OR

  • Children & adolescents (excluding infants less than 12 months)

Excludes populations exclusively selected on the basis of disease (e.g. diabetes, cardiovascular disease)

All populations:

  • All-cause mortality
  • All-cause morbidity

Chronic condition risk factors

  • Cancer risk factors
  • Cardiovascular disease risk or related factors
  • Type 2 diabetes risk or related factors
  • Overweight/obesity or related size measures
  • Mental health (depression and anxiety)
  • Reproductive health
  • Gastrointestinal health
  • Iron deficiency anaemia in women of childbearing age

Healthy Aging

  • Quality of Life
  • Neurocognitive health including dementia
  • Sarcopenia
  • Bone health

Outcomes prioritised for children and adolescents only:

  • Child growth (including overweight/obesity)
  • Child development (including neurocognitive development)
  • Asthma, allergies allergic syndrome 
  • Mental health
  • Iron deficiency anaemia

Outcomes prioritised for pregnant & breastfeeding people only: 
Maternal health outcomes

  • Gestational diabetes risk
  • Pregnancy-related hypertensive disorders risk
  • Pregnancy-related weight gain/postpartum loss
  • Pre/post-natal depression
  • Iron deficiency anaemia

Breastfeeding specific outcomes

  • Human milk production

Birth outcomes

  • Birth metrics (weight/gestational age at birth/preterm)
  • Stillbirth/miscarriage

Outcomes in the infant/child

  • Asthma, allergies or allergic syndromes
  • Child growth (including overweight/obesity)
  • Child development (including neurocognitive development)

Dietary patterns* and health outcomes:

  • dietary patterns vs other dietary patterns OR
  • high similarity to a specific dietary pattern vs low similarity to that dietary pattern

Intake of animal vs plant sources of protein and health outcomes:

  • protein intake from plant-based sources vs protein intake from animal sources OR
  • high intake of plant foods vs low intake of plant foods OR
  • high intake of animal foods vs low intake of animal foods OR
  • dairy vs dairy alternatives

Ultra-processed food intake and health outcomes:

  • high intake of ultra-processed foods vs no/low intake of ultra-processed foods

Meal patterns (eating behaviour) - Frequency of eating occasions and health outcomes:

  • frequency of eating vs different meal pattern frequency OR varying levels of frequency of eating OR different meals patterns

Meats, poultry, fish, eggs, nuts and seeds, legumes/beans (including pulses and tofu):

  • red meat intake vs white meat OR
  • high intake of legumes/pulses vs no/low intake of legumes/pulses

* Dietary patterns must be relevant at a population level, e.g. Mediterranean diet, food patterns high in fat sources with high omega 3/PUFA/MUFA, plant-based diets.

Table 2. PI/ECO criteria for questions focused on contextual factors
Populations
At least one of the following: 		Outcomes
At least one of the following outcomes:		 Contextual factors
At least one of the following:

Includes:

  • Adults (including older adults, and those at risk of chronic disease)

AND/OR

  • Pregnant & breastfeeding people

AND/OR 
Children & adolescents (excluding infants less than 12 months) 
Priority subpopulations of interest

  • Aboriginal and Torres Strait Islander people
  • Culturally and linguistically diverse (CALD)
  • Lesbian, gay, bisexual, transgender, queer or questioning, intersex and/or other sexuality and gender diverse people (LGBTQI+)
  • People with mental illness
  • People of low socioeconomic status
  • People with disability
  • Rural, regional and remote populations

Excludes populations exclusively selected on the basis of disease (e.g. diabetes, cardiovascular disease)

Consumption aligned with guidelines:

  • point in time consumption
  • life course consumption

Influence of eating environment/context and consumption aligned with guidelines: 
Factors relating to eating environment/context, including

  • home-based factors (e.g. family meals, use of technology during mealtimes)
  • factors relating to other environments (e.g. school, workplace, community)

Barriers and enablers to consumption aligned with guidelines:

  • Food security
  • Other barriers and enablers to consumption of foods aligned with guidelines (e.g. food literacy/skills)

Interventions/strategies to improve diet and eating behaviours:

  • Interventions/strategies to improve dietary patterns and eating behaviours aligned with the guidelines across the life course

Excludes interventions/exposures that are for treatment of disease (e.g. diabetes, cardiovascular disease).