DRAFT Australian Dietary Guidelines - Eat For Health

2.1.3 How eating a wide variety of nutritious foods may
improve health outcomes
Nutritional science has traditionally characterised foods according to their macro- and micronutrient
values, but there is increasing evidence of the role that whole foods play in promoting
health and wellbeing, and of the role of food components other than nutrients in protecting
against some communicable and non-communicable chronic diseases when consumed as part of a
varied nutritious diet [108, 109]. These non-nutrient components include phytochemicals, which
are obtained from plants and are biologically active but not directly associated with deficiency
syndromes. They include carotenoids, flavonoids, isoflavonoids, polyphenols, isothiocyanates,
indoles, sulphoraphanes, monoterpenes, xanthins and non-digestible oligosaccharides. It is not
always known which food constituents are responsible for the protective effects of specific foods
against specific chronic diseases, and it is likely that many other active constituents will be
discovered in the future. Interactions between these compounds are likely to be complex, either
causing or masking effects, or acting synergistically with other compounds [10].
Dietary variety has the benefit of diluting potential toxicants found naturally in foods [110].
Enjoying diversity in food intake can reduce an individual’s exposure to any one group of toxicants.
Other ways of minimising this risk include appropriate and careful processing, cooking and storage
of food (see Chapter 7).
Another potential benefit of food variety comes from maximising the bioavailability of nutrients
[111]. The many complex relationships between foods, nutrients and food components (such as
phytates) can influence the absorption, metabolism and retention of nutrients. When dietary
patterns are varied and nutrients are in adequate supply, these interactions pose fewer problems
than in restricted, monotonous dietary patterns.
Clinical problems associated with excessive intake of nutrients are nearly always associated with
intakes of supplements [9]. It is also possible to develop symptoms of toxicity when dietary
patterns concentrate on particular foods, or if the same nutrient is consumed in different chemical
forms [9, 112]. Examples include excessive consumption of carrot juice or regularly eating very
large quantities of liver, which may cause vitamin A toxicity [113].
2.1.4 Practical considerations: Eat a wide variety of
nutritious foods
It is important to consider this guideline together with other guidelines, particularly Guideline 2 on
limiting intakes of specific foods high in saturated fats, added sugars and/or added salt and
Guideline 3 on healthy weight. The word ‘plenty’ is used judiciously to encourage increased
consumption of vegetables (particularly non-starchy varieties). For the other food groups, the
guidelines do not advocate plenty, but rather focus on an adequate amount of the preferred
DRAFT Australian Dietary Guidelines- December 2011 28