![]() For those nutrients where an AI was set, a value of 83% AI was used in modelling as this gave a rough equivalence to the relativity between the EAR and RDI (ie it is 2CV below the AI assuming a CV of 10% for the EAR, as used to derive RDIs where the variability in requirements is unknown). For modelling purposes, vitamin D was also excluded as much of this can be accessed through the action of sunlight on skin. Firstly, an assessment was undertaken of 2-day adjusted, daily diets reported in the 1995 National Nutrition Survey for Australia (ABS 1998) in relation to macronutrient profile, energy intake and EARs (or a proportion of the AIs) for all nutrients except sodium, fluoride, biotin, selenium, choline, chromium, iodine and molybdenum, for which reliable analytical food data were not available. It is important to remember that these recommendations are recommendations for otherwise healthy people and it is assumed that usual dietary intake will be at a level to maintain current body weight (ie these are not necessarily recommendations for optimal weight loss diets or for treatment or management of existing chronic disease conditions).ĭietary modelling involved two approaches. Given these limitations, an expert review of the evidence base described in the US:Canadian DRI review, together with consideration of papers published since the review, and dietary modelling to assess the effects of changes in macronutrients on micronutrients, was used to develop AMDRs for use with adults in Australia and New Zealand. If a benefit or adverse effect is seen, it is not immediately clear what is responsible for the observed outcome. For example, in assessing the effects of a high carbohydrate diet on a specific endpoint, the test diet must be relatively low in fat and/or protein and/or vary in its energy content. Studies of individual macronutrients are particularly prone to confounding by the other necessary changes to the diet (ie either the energy content changes in the control group and/or the proportion of other macronutrients). Randomised controlled trials, which provide the most conclusive evidence of causality, are often lacking in relation to optimising macronutrient profile. ![]() Much of the evidence is based on epidemiological studies with clinical endpoints but these studies generally show associations rather than causality and are often confounded by other factors that can affect chronic disease outcomes. In their document, they extensively reviewed the current evidence, in terms of outcomes such as body weight maintenance, obesity, CHD and LDL oxidation, stroke, Type 2 diabetes, hyperinsulinaemia and glucose tolerance, metabolic syndrome, cancer, osteoporosis, renal failure, renal stones, inflammatory disorders and risk of nutrient inadequacy in adults, as well as some of these outcomes, plus birth weight and growth in relation to children. The Food and Nutrition Board of the Institute of Medicine in constructing the US:Canadian Dietary Reference Intakes (FNB:IOM 2002) called this range the Acceptable Macronutrient Distribution Range (AMDR). The risk of chronic disease (as well as the risk of inadequate micronutrient intake) may increase outside these ranges, but often data in free-living populations are limited at these extremes of intake. There appears to be quite a wide range of relative intakes of proteins, carbohydrates and fats that are acceptable in terms of chronic disease risk. This has not always been given enough consideration in study design or interpretation. However, the form of fat (eg saturated, polyunsaturated or monounsaturated or specific fatty acids) or carbohydrate (eg starches or sugars high or low glycaemic) is also a major consideration in determining the optimal balance in terms of chronic disease risk. There is a growing body of evidence that a major imbalance in the relative proportions of macronutrients can increase risk of chronic disease and may adversely affect micronutrient intake. Thus, for example, a high fat diet is usually relatively low in carbohydrate and vice versa and a high protein diet is relatively low in carbohydrate and/or fat. ![]() For a given energy intake, increases in the proportion of one macronutrient necessarily involves a decrease in the proportion of one, or more, of the other macronutrients. The effect of alcohol on health outcomes has been reviewed elsewhere and will not be revisited here except to say that alcohol intakes below about 5% of dietary energy are recommended (NHMRC 1999, 2003). Alcohol can also contribute to dietary energy. Unlike the micronutrients, the macronutrients (proteins, fats and carbohydrates) all contribute to dietary energy intake.
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