Our Dietary Guidelines: better, but good enough?

Following consultation with stakeholders, the draft Australian Dietary Guidelines have been further refined, with some improvements in relation to cereal fibre, trans fats and added sugar. Even the mess around saturated fats has been tidied up a bit, but is it enough? 

The first post on The Sceptical Nutritionist highlighted several problems with the draft Australian Dietary Guidelines and these have been discussed in detail in recent months. Encouragingly, some of the issues appear to have been addressed during the consultation period. The clues come in a draft appendix to the Australian Dietary Guidelines that was recently released for consultation, which includes the latest version of the key Dietary Guidelines statements.

More emphasis on cereal fibre

There is now greater emphasis on cereal fibre. The previous statement that recommended cereal foods should be ‘mostly wholegrains’ has been changed to ‘mostly wholegrain and/or high cereal fibre varieties’. This is consistent with the science as many of the studies used to support the wholegrains recommendation used high fibre foods, suggesting that recommending high fibre cereal foods was equally valid.

Trans fats

Another positive development was the removal of trans fats from the key Dietary Guidelines statements. As no systematic literature review on trans fats was conducted and there was hardly any discussion about trans fats in the text of the Guidelines, the rationale for emphasising trans fats was a mystery. After all, the level of trans fats in the Australian diet is low, just half the maximum level recommended by the World Health Organization. Also, as most of the trans fats in the Australian diet now come from meat and dairy fat, advice to lower saturated fat from these sources also serves to further lower intake of trans fats.

Image: source

Added sugar

The original guideline statement advocating that intake of foods and drinks containing ‘added sugars’ be limited was criticised for not being scientifically based. Compared with starch, sugar has no adverse health effects, so why limit it? And why make a distinction between naturally occurring and added sugars? Also, blanket advice to limit foods with added sugar had the potential to adversely affect diet quality as some foods with added sugar, such as flavoured milk, fruity yoghurts and breakfast cereals, are nutrient-rich. What logic is there to limiting nutrient-rich foods on the basis of their sugar content? Do nutritionists recommend limiting intake of oranges because they contain sugar?

The latest version of the guideline statement on sugar at least takes a step in the right direction, stating Limit intake of foods and drinks containing added sugars such as confectionery, sugar-sweetened soft drinks and cordials, fruit drinks, vitamin waters, energy and sports drinks. This focusses attention on limiting nutrient-poor sources of sugar. But if ‘empty calories’ is the concern, why not go all the way and make nutrient density a criterion on which the nutritional quality of foods is judged? Why bother with sugar at all?

The saturated fat debacle

Saturated fat was very poorly handled in the early stages of the development of the Dietary Guidelines.

• Amazingly, no systematic literature review was conducted and consequently the process missed a significant development in the science of how macronutrients affect the risk for coronary heart disease i.e. that carbohydrate confers the same risk as saturated fat. Recommended ‘healthy’ diets were low in saturated fat and high in carbohydrate, the authorities apparently unaware of the contradiction. Not surprisingly, the relevant chapter in the text of the draft Guidelines was out of date and poorly argued.

• There was blind adherence to the notion that a healthy diet needs to be low in fat – all of the modelled Foundation Diets were low in fat. A process that was supposed to be ‘based on the best available scientific evidence’ somehow managed to miss the four reports of the Women’s Health Initiative, the largest randomised controlled dietary trial ever conducted, which showed that a low fat diet has no effect on the risk for cardiovascular disease, breast cancer and bowel cancer, and minimal effect on body weight.

• A major concern was that unsaturated fat, which had emerged as the most protective class of macronutrients in relation to coronary heart disease, was restricted. The science is clear – unsaturated fat is the preferred replacement for saturated fat. Intake of unsaturated fats needs to increase, not decrease.

• Instead of encouraging the use of vegetable oils and spreads – the major source of unsaturated fats in the Australian diet, there was a bias against their inclusion. This bias was evident in dietary modelling. Unsaturated oils and spreads were categorised differently to the other 12 groups of foods modelled, the inclusion of oils and spreads being simply to ‘reflect current culinary behaviour’. However, the dietary modelling actually demonstrated a significant and distinctive nutritional contribution, the modelled margarine being a major source of vitamin A, vitamin D, vitamin E, linoleic acid and α-linolenic acid, as well as being instrumental in achieving the desired ratios of fatty acids.

• This bias against unsaturated vegetable oils and spreads, a reflection of a belief system rather than nutrition science, was carried through into the key Dietary Guidelines statements and the draft Australian Guide to Healthy Eating. The first guideline statement ‘Eat a variety of nutritious foods …’ included reference to all foods in the food groups modelled, except for unsaturated oils and spreads. So it was not an accurate translation of the dietary modelling into key Dietary Guidelines statements. Dogma at work. Similarly, the advice about the use of unsaturated oils and spreads in the Australian Guide to Healthy Eating was to ‘use small amounts’ i.e. to restrict the use of these foods, contrary to the science.

What a mess.

Image: source

Some progress

The good news is that there has been some progress on this issue. Apparently, the chapter on saturated fat has been re-written and is now said to be consistent with the science. And the wording of the key Dietary Guidelines statement relating to saturated fat has been changed. The original wording was ‘Limit intake of foods and drinks containing saturated … fats’ and included advice to ‘include small amounts of foods that contain unsaturated fats’.

The latest draft Guidelines statement provides much greater details on which sources of saturated fat should be limited:

Limit intake of foods containing saturated fat such as many biscuits, cakes, pastries, pies, processed meats, commercial burgers, pizza, fried foods, potato chips and crisps and other savoury snacks.

and, importantly, that foods rich in unsaturated fats should replace saturated fat in the diet:

Replace high fat foods which contain predominantly saturated fats such as butter, cream, cooking margarine, coconut and palm oil with foods which contain predominantly polyunsaturated and monounsaturated fats such as oils, spreads, nut butters/pastes and avocado.

The removal of the term ‘small amounts’ in relation to unsaturated oils and spreads is a positive move. For consistency, these words will also need to be deleted from the Australian Guide to Healthy Eating. We shall see.


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