New nutrient reference values for Australia and New Zealand: implementation issues for nutrition professionals.
The process of development was that the USA/Canada values were used as the starting point, and experts were asked to report on whether these reflected the most current knowledge, and whether they reflected unique attributes of Australia and New Zealand (such as current intakes and the food supply). These reviews were then in turn discussed by an expert working party that included individual experts as well as representatives of nutrition professionals and the food industry. Dietary modelling was used to determine if it was possible to achieve the levels with various food combinations. The recommendations were then subjected to public consultation, further refinement and then an internal, National Health and Medical Research Council (NHMRC) quality assurance process. Final recommendations were accepted by both governments late in 2005.
The process of development followed a rigorous, evidence-based system, values being generated from evidence graded by the NHMRC taxonomy of quality. (3) This is a very different process to that used to develop the food grouping system (4) and the Australian Guide to Healthy Eating. (5) It also differs somewhat to previous versions of RDI values, as our understanding and acceptance of quality in terms of evidence has changed. When a process such as this is used, our certainty is reduced for some nutrients where the evidence is limited or less powerful. The application of uncertainty factors has, therefore, tended to confirm somewhat higher RDIs for some nutrients.
The RDIs, EARs and AIs remain recommendations for the avoidance of deficiency diseases. RDIs are derived from the EAR, so when this is not known or unclear, AIs based on the mean intake of the population known not to have a deficiency has been adopted. Therefore, in general, AIs are higher than EARs but lower than an RDI might be as these have safety factors based on assumed coefficients of variation. The ULs relate to the avoidance of toxicity or other symptoms.
The NRV document also includes a section on chronic disease prevention for people aged over 14 years--a significant innovation as it links nutrients to disease prevention in a systematic way. The SDTs in this section are likely to be extensively used by nutrition professionals. They suggest that for some key nutrients, intake levels should be at the 90th centile of the 1995 national nutrition survey (Australia) and the 1999 national survey (New Zealand). Clearly, therefore, for 90% of the population, if intakes have remained steady, this suggests that an increase in these key nutrients will be necessary for potential reduction of risk of some chronic diseases. Only nutrients where there is strong evidence for benefit were selected. The 90th centile was chosen as it is the mid-point of the highest quintile and the evidence is clear that those with the highest quintile intakes of these nutrients fare better in terms of heart disease in particular but also some cancers. There is also an acceptable macronutrient distribution range identified, giving guidance on the balance between protein, fat and carbohydrate. A greater emphasis is placed on protein in the diet (15-25% of energy) and the type of fat rather than focusing only on the quantity of fat. Dietary modelling supported the result that the required nutrient levels could not be attained with lower protein intakes, despite the actual requirement for protein being lower. Issues for implementation, therefore, include potential conflict between nutrition messages in terms of the food groups and the quantities of those foods that make up a healthy diet.
Nutrition professionals have traditionally used RDIs as benchmark values when assessing either intakes of individuals or groups and to evaluate menus for their appropriateness. We have elected to follow the principles of application used by the USA/Canada. (6) EARs should not be used for assessing intakes of individuals, but should be used to assess the risk of inadequacy in a group. At the individual level the target for adequacy (not disease prevention) should be the RDI or AI levels but less than UL levels. This change in use requires caution when using computerised nutrient analysis software. Members of the public should be cautioned about exceeding the ULs on a daily basis, while increasing intakes up to the RDI or the SDTs.
A major issue facing us in Australia (but less so in New Zealand) is the lack of up-to-date food composition data for most nutrients and any food composition data for some nutrients (such as molybdenum, copper, chromium and biotin). We will have to continue to use the philosophy that diets that are adequate in terms of those nutrients that we can estimate will be adequate also in those nutrients we cannot. This is a major issue for the quality of nutrition assessment and advice.
In the next few years there will be a need to determine the value used in food labelling, and the differing depiction of a 'healthy diet'. The new values suggest that twice as many vegetables and more from the meat and meat equivalent group will be necessary. The issue of the food supply will arise. Already we are seeing calcium added to an array of foods, as well as the n-3 fats and folate. This will make it somewhat more challenging to provide detailed advice. Traditionally, nutrition professionals have tended to speak only in terms of the 'core foods', as typified by The Australian Guide to Healthy Eating (7) and this will become less valuable.
It is, therefore, urgent that nutrition professionals familiarise themselves with the background and detail of the NRVs as these represent one of the most important changes in fundamental nutrition tools in this decade. The materials are online as is the evidence guide containing the background information. Although it may be tempting to merely read the executive summary with the tables, it is important that nutrition professionals have a clear understanding of the detail. The full material contains much additional material, such as special cases and caveats, which are necessary for their correct and appropriate use. We also need to advocate strongly for reviews of the food selection guides, the nutrient database and the NRVs on a regular basis.
Sandra Capra, AM, PhD, FDAA
Professor of Nutrition and Dietetics
University of Newcastle
1 Cobiac L, Dreosti I, Baghurst K. Recommended Dietary Intakes--Is It Time for a Change? Canberra: Commonwealth of Australia, 1998.
2 Commonwealth Department of Health and Ageing Australia, Ministry of Health, New Zealand, National Health and Medical Research Council. Nutrient Reference Values for Australia and New Zealand including Recommended Dietary Intakes. Canberra: Commonwealth of Australia and New Zealand Government, 2005.
3 National Health and Medical Research Council. How to Use the Evidence: Assessment and Application of Scientific Evidence. Canberra: Commonwealth of Australia, 2000.
4 Cashel K, Jeffreson S, The Core Food Groups. The Scientific Basis for Developing Nutrition Education Tools. Canberra: National Health and Medical Research Council, Commonwealth of Australia, 1995.
5 Smith A, Kellet E. Development of the Australian guide to healthy eating 1: background and rationale. Aust J Nutr Diet 1999; 56: 188-94.
6 Institute of Medicine of the National Academies. Dietary Reference Intakes, Applications in Dietary Planning. Washington, DC: National Academies Press, 2003.
7 The Australian Guide to Healthy Eating. Canberra: Commonwealth Department of Health and Family Services, 1998.
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|Publication:||Nutrition & Dietetics: The Journal of the Dietitians Association of Australia|
|Date:||Jun 1, 2006|
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