Recommended dietary intakes

2006 Australia and New Zealand Recommended Dietary Intakes (RDIs) - the recommended amounts for most vitamins and minerals have increased since 1991 which means we need to eat more nutrient dense/fortified foods and less nutrient poor foods to achieve these higher RDIs.
Table has been adapted from Australian Government Dept of Health and Ageing and National Health and Medical Research Council 2006 publication.

1991 Australian Recommended Dietary Intakes

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Recommendations about intakes of specific nutrients are known as "Recommended Dietary Intakes" (RDI's). The RDI's generally refer to vitamins, minerals, energy and protein.

Recommendations for other macronutrients are generally defined as their energy contribution to the total dietary energy. Such energy ratios are not very useful on a day-to-day basis, but they are useful in identifying imbalances in populations’ diets and devising guidelines to correct them.

Although recommendations about nutrient intakes are made in terms of daily intakes, not all nutrients are needed every day. Most can be stored to a lesser or greater extent in our bodies. The macronutrients that provide energy are stored in the liver and muscles in the form of glycogen, and in adipose tissue and muscles in the form of triglycerides.

The body stores of vitamins vary from one individual to another according to the general state of nutrition and health. The stores of the fat-soluble vitamins are usually higher than those of the water-soluble vitamins. However, even the stores of the latter are sufficient to protect the well nourished individual for many days or even months. For example, it may take as long as 80-90 days before the symptoms of scurvy appear if one eats a diet without vitamin C.

It is estimated that body stores of vitamin B12 are adequate for more than two years and a diet lacking vitamin A will not lead to clinical signs of deficiency for several months.

Consequently, well nourished individuals are usually able to withstand periods of deprivation or periods of increased need such as occur with pregnancy and lactation. They are also at an advantage when stressed by disease or trauma. Undue concern about particular food preferences, for example about children who seem to want one kind of food and not another for a few days, is unnecessary. As long as a variety of foods are eaten over a period of time, the range of essential nutrients should be provided. 

RDI's are the amounts of essential nutrients that are considered adequate to meet the nutritional requirements of healthy people. The RDI's are designed to easily prevent classical nutritional deficiency diseases, such as scurvy, beri-beri, pellagra, rickets and anaemia. Indeed, there is a wide margin of safety. However, they do not address the extra nutrient needs of persons with certain chronic ailments, who smoke, or who are on drug medication.

New research suggests a greater role for vitamins (and minerals) in the prevention or slowing down of many diseases such as heart disease, cancer, cataracts, osteoporosis and birth defects. The total effects of vitamins on the body are still not fully known or understood. Further, there is increasing scientific evidence to suggest that higher levels of certain vitamins (e.g. antioxidants vitamins C, E, and beta-carotene) may be necessary for optimal health, and may provide extra protection against cancer, heart disease and other diseases.

In time, the concept of RDI may well be broadened to include a second set of much higher vitamin levels that optimise their disease-preventing properties. From the medical practitioner's point of view, it is particularly important to remember that RDI's are for healthy people. In illness the requirements for many nutrients are altered. For example, with stress, trauma or surgery, the requirement for vitamin C may be more than 8 times the RDI for healthy adults; zinc requirements increase for wound healing. 

Individuals have widely varying nutrient requirements - both from person-to-person and from day-to-day. RDI's should be used with caution in assessing an individual's diet. There needs to be corroborating evidence (e.g. biochemical measures) before a person's diet can be declared to be inadequate on the basis of a comparison with the RDI's alone. The likelihood of an inadequate diet increases with the extent to which intake is below the RDI.

The RDI's do not allow for illness, medications or the effects of major life stresses, smoking, alcohol abuse.

They assume a certain nutritive quality, biological value or availability of the various nutrients.

They assume adequate intakes of other major nutrients and energy and do not allow for interactions between nutrients.

They do not allow for adaptation to high or low intakes of some nutrients (e.g. iron, calcium, energy) for the individual.

They generally do not indicate toxic levels of intakes.

They do not cover the proportional distribution of energy between carbohydrates, fats and proteins - nor do they address the minor vitamins and trace elements (it is assumed that if the intake of the main nutrients is adequate, then the requirements for the others will automatically be covered).

Last Updated: January 29, 2002