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Adequacy of essential fatty acid, vitamin D and vitamin E intake: implications for the 'core' and 'extras' food group concept of the Australian Guide to Healthy Eating.

Article Excerpt
Abstract

Objective: To assess the implications of new recommendations for essential fatty acids, vitamin D and vitamin E on the classification of margarines and vegetable oils as 'extras' in the current Australian Guide to Healthy Eating.

Design: The role of margarines and vegetable oils as sources of essential fatty acids, vitamin D and vitamin E was examined in two ways. First, data from the 1995 National Nutrition Survey were assessed and, second, sample diets conforming to the Australian Guide to Healthy Eating were modelled and analysed.

Subjects: For the assessment of national intake, subjects were a representative sample of 13858 Australians, surveyed in the 1995 National Nutrition Survey.

Main outcome measures: Relative contributions of margarines and oils, the 'core' food groups and 'extras' categories of the Australian Guide to Healthy Eating to intakes of essential fatty acids and vitamins D and E; changes in nutrient profiles of baseline diets conforming to the Australian Guide to Healthy Eating with or without varying amounts of margarines and oils.

Results: 'Core' foods and 'extras' contributed similar amounts of essential fatty acids and vitamins D and E to the Australian diet, margarines and oils being the major contributor among 'extras'. The simulated low-fat, low-saturated-fat baseline diets generally failed to meet the adequate intakes for n-3 and n-6 polyunsaturates and vitamin D, and vitamin E in some instances. The addition of 25 g of sunflower margarine, but not comparable amounts of canola margarine, olive oil and butter, markedly increased the ratio of polyunsaturated to saturated fatty acids and generally delivered the adequate intakes, vitamin D being the exception.

Conclusion: The inclusion of margarines and vegetable oils in diets based on the current Australian Guide to Healthy Eating, and guidance on choice among these foods, is required to provide adequate intakes of linoleic acid, [alpha]-linolenic acid and vitamins D and E and to achieve fatty acid profiles consistent with the prevention of chronic disease.

Key words: adequate intake, 'core' food, dietary modelling, essential fatty acids, vitamin D, vitamin E.

INTRODUCTION

In 1998, the Australian Guide to Healthy Eating (the Guide) was developed to replace the Five Food Groups, which had been the Commonwealth Government's official food guide for nearly five decades. Impetus for a new food guide came from a need to address diseases of overconsumption in addition to the traditional focus on nutritional adequacy. Six government-funded reports provided the basis for the development of the Guide. (1-6)

The pictorial version of the Guide depicts five groups of 'core' foods recommended for regular consumption and a group of 'extras' for consumption sometimes or in small amounts. Supporting literature states that eating a variety of 'core' foods '... is highly likely to result in a diet containing sufficient amounts of all essential nutrients for health'. 'Extras', on the other hand, '... are not essential to provide the nutrients the body needs'. (7) Thus, the distinguishing attribute of 'core' foods is their capacity to deliver essential nutrients to the Australian diet.

The positioning of margarines and vegetable oils in the Guide is ambiguous. In the pictorial version margarines and vegetable oils are included in 'extras', yet diets based on the Guide allow a teaspoon of margarine or oil be included per 0.6 of every bread or cereal serve, implying some added fats may add nutritional value to the diet. (7) Although the supporting literature of the Guide states the main nutritional contribution of fat spreads is vitamin A, margarines also contain linoleic acid, [alpha]-linolenic acid and vitamins D and E. 'Adequate intakes' for these nutrients were established in the recent Nutrient Reference Values report. (8) These new recommendations (Table 1) provide benchmarks against which the Guide can be assessed.

The purpose of the present research was:

1 To assess the contribution of 'extras', especially margarines and vegetable oils, to the content of linoleic acid, [alpha]-linolenic acid and vitamins D and E in the Australian diet....

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