The revision to the 2013 Australian Dietary Guidelines (the Dietary Guidelines or the Guidelines) is currently in the evidence review phase.

The Dietary Guidelines Expert Committee (Expert Committee) identified priority diet and nutrition topics for review based on detailed scoping and consultation. High priority research questions were then identified based on public health considerations and the likelihood of significant new evidence having emerged since the 2013 Guidelines. More information about this is in the two Prioritisation Process Reports – one for older Australians and one for the general population.

Evidence mapping activities have identified existing, high-quality systematic reviews for some of the priority questions. These will be used to update the evidence for these questions. Where important evidence gaps remain, the Expert Committee has requested 4 new evidence reviews be commissioned.

Research questions and types of evidence reviews

General questions

Three scoping reviews and one systematic review have been commissioned.

Research questions for scoping reviews:

  • dietary patterns versus a different dietary pattern/low adherence to the same dietary pattern and incidence of anxiety or depression in adults, children and adolescents or incidence of pre/post-natal depression during pregnancy and breastfeeding.
  • high versus low consumption of ultra-processed food (UPF) in children and adolescents (2–17 years of age) on the outcomes of: incident anxiety and depression; development of asthma; development of dietary allergies and development of developmental neurocognitive conditions.
  • the impact of dietary patterns, source of protein or UPF consumption during pregnancy and breastfeeding on maternal and birth outcomes.

Research question for the systematic review:

  • high versus low consumption of UPF in adults on the outcomes of: all-cause mortality; cardiovascular events and cardiovascular mortality; incidence of type 2 diabetes; cancer events and cancer mortality; and incidence of anxiety and depression.

Older adults

Two scoping reviews are being commissioned on the following research questions (and sub-questions) in the general adult population 65 years and older (or 50 years and older for Aboriginal and Torres Strait Islander peoples):

  • intake of protein-rich foods and development of sarcopenia (age-related muscle wasting)
  • intake of protein-rich foods and development of neurocognitive conditions (including dementia and Alzheimer disease) or impairments.

For both reviews, intake of protein-rich food will include looking at:

  • high versus low intake of animal protein-rich foods
  • high versus low intake of plant protein-rich foods
  • animal protein-rich foods versus plant protein-rich foods.

Diet and economic, social and environmental sustainability

Two scoping reviews are being commissioned to identify:

  • What studies are available on the environmental impact of consuming different dietary patterns, protein-rich foods and ultra-processed foods (UPFs) in the Australian context?
  • What studies are available on the implications of different dietary patterns on socio-cultural acceptability, accessibility, equity, cost and affordability of food in the Australian context?

Both scoping reviews will report:

  • the characteristics and findings of studies identified
  • identified evidence gaps.

What is the difference between systematic reviews and scoping reviews?

Systematic reviews try to answer research questions by collating information from individual research studies (primary studies). Before work begins, the research question and the methods to be used must be clearly stated, including which primary studies are eligible to be included. They take a thorough and transparent approach in collecting and considering the results of primary studies, to minimise bias and improve the reliability of the review findings.

Scoping reviews are exploratory, and often address a broader question than a systematic review. Scoping reviews may assess the extent of the available evidence, organise it into groups and highlight gaps.

For example, while a systematic review may try to answer a research question about whether eating vegetables reduces the risk of cardiovascular disease, a scoping review may try to identify if there are primary studies that can answer this research question and describe the characteristics of these studies. If a scoping review finds no studies, this might help researchers decide a systematic review is likely to be of limited value and resources could be better directed elsewhere.

More detail about the types of reviews can be found in the Dietary Guidelines Evidence Review Strategy.

Why topics were chosen

Ultra-processed foods

Stakeholders are interested in ultra-processed foods. In the NHMRC 2021 stakeholder survey, the most requested new topic was food processing, including ultra-processed foods. The Expert Committee also considered ultra-processed foods and health outcomes a high priority for review as it is an active area of research and there is likely to be significant new evidence since the 2013 Dietary Guidelines.

Anxiety and depression

Very few systematic reviews addressing mental health as an outcome were found during mapping of existing systematic reviews. The Expert Committee considered this an important gap and requested exploration of primary studies to better understand the existing evidence.

Although there are many potential mental health outcomes that could be measured, the Expert Committee chose to focus on anxiety and depression. This is consistent with these conditions being identified as the highest priority during the prioritisation process, as they account for the highest burden of mental illness in Australia.

Evidence reviewers will first explore whether there is enough reliable evidence available to address the research question via a scoping review. If so, they may be asked to conduct a systematic review of the evidence.

Dietary patterns and pregnancy/breastfeeding

The Expert Committee found there was a general lack of good quality systematic reviews for this group after mapping existing systematic reviews was completed. They advised it is important to explore whether there are primary studies that can address this topic.

Evidence reviewers will first explore whether there is enough reliable evidence available to address the research question via a scoping review. If so, they may be asked to conduct a systematic review of the evidence.

Protein-rich foods and sarcopenia and neurocognitive conditions in older adults

Limited high-quality systematic reviews addressing protein-rich food consumption and sarcopenia and neurocognitive conditions were found after mapping existing systematic reviews to the priority research questions.

Evidence reviewers will first explore whether there is enough reliable evidence available to address the research question via a scoping review. If so, they may be asked to conduct a systematic review of the evidence.

Diet and economic, social and environmental sustainability

The Dietary Guidelines Sustainability Working Group considered it important to understand diet and economic, social and environmental sustainability in the Australian context. The Working Group acknowledged information published by recognised international groups on diet and sustainability. However, Australian consumption patterns, food production methods, extent of food importation and the Australian environment may differ from other countries.

These scoping reviews will provide the Working Group with information about available Australian studies. This will assist them in their role of providing advice to the Expert Committee on the strength and quality of evidence on diet and economic, social and environmental sustainability.

Process for completing new evidence reviews

NHMRC has rigorous standards in place to ensure that guidelines and public health advice are high quality and based on the best available scientific evidence. Infographics are available which outline:

A public call for primary research studies for some of the commissioned evidence reviews was held. For details about what primary studies were eligible for inclusion visit, Public call for peer-reviewed primary research studies eligibility criteria and research questions.

The new evidence reviews for the Dietary Guidelines revision will be completed as outlined in the Dietary Guidelines Evidence Review Strategy. 

Independent evidence reviewers (with expertise in nutrition and conducting evidence reviews) will complete the new evidence reviews. The protocols and Evidence Evaluation Reports for the new reviews will be reviewed by an independent methodological expert, a consumer reviewer and the Expert Committee.

Suppliers to complete the new evidence reviews were sought through AusTender. The tenders are now closed. For questions about applications or the tenders, contact the Procurement Contact Officer at tenders@nhmrc.gov.au.

For answers to questions about the new evidence reviews, visit the Frequently Asked Questions.