Seven problems with the Dietary Guidelines

The draft Australian Dietary Guidelines were recently put out for consultation and after a four-year gestation we might have expected a highly polished report, clearly communicating the latest evidence-based nutrition. The reality was very different. The draft Australian Dietary Guidelines report was a very strange document with nutrition science jostling awkwardly with motherhood and ideology. Some important areas of the nutrition literature were reviewed in great depth, but others were not reviewed at all and significant shifts in the science were missed. The translation of the findings of literature reviews into dietary advice appeared to be compromised in two ways – by a conservatism that didn’t want to see change to long-standing messages about diet and health and an activism for change driven by environmental concerns, not by nutrition science.

As a result the Guidelines fall short scientifically in seven areas. These are reviewed below and will be considered in more depth in the weeks ahead.

Low fat diets

The Dietary Guidelines continue to advocate diets low in fat, despite there being no scientific justification for this approach. None of the systematic literature reviews conducted during the development of the Guidelines established a link between total fat intake and any condition of public health significance, including obesity. Nevertheless, the low fat approach was still embraced on the grounds that it was ‘prudent’. This is dietetic dogma at work – my term for the conservative mindset that just can’t let go of old dietary advice, even when it is no longer scientifically valid.

Controversially, the Guidelines recommend restriction of all types of fat in the diet, even unsaturated fats which are considered to be protective against coronary heart disease. In an article in The Australian newspaper in March 2012 a leading Australian nutrition scientist, the Heart Foundation and the Dietitians Association of Australia all criticised this aspect of the Guidelines. This problem arose because key literature on saturated fat, carbohydrate and heart disease was simply not reviewed.

Saturated fat, carbohydrate and heart disease

Limiting saturated fat intake has been a fixture in many Dietary Guidelines for years on the grounds that saturated fat raises the level of LDL-cholesterol in the blood, thereby increasing the risk for coronary heart disease. In Australia the preferred replacement for saturated fat has been carbohydrate, encouraging diets low in both saturated fat and total fat. However, a key study published in 2009 confirmed that carbohydrate and saturated fat confer the same risk for heart disease, so swapping one for the other has no effect on risk. As a consequence, unsaturated fats have become the recommended replacement for saturated fat and this approach has been incorporated into the Dietary Guidelines for Americans (2010).

It is hard to believe that there was no systematic literature review into the role of saturated fat in heart disease risk during the development of the latest Australian Dietary Guidelines. Instead, the literature review for the 2003 Dietary Guidelines was relied upon. So in this key area, the Dietary Guidelines are out of date, inconsistent with the dietary guidelines of other countries and inconsistent with the positions of many leading research and nutrition authorities.

The higher-than-expected risk of dietary carbohydrate has highlighted the need to eat less carbohydrate (not less fat) and to choose ‘good’ carbohydrate foods. But what do the Dietary Guidelines tell us about carbohydrate quality?

Added sugar

The Dietary Guidelines recommend that intake of foods with ‘added’ sugar be limited. But is the amount of added sugar in a food really a good measure of its nutritional quality? Certainly, sugary foods and drinks can increase the risk of tooth decay, especially in those with poor oral hygiene, but this is also a problem with natural sugars. The same goes for the starch found in rice, potato or bread which breaks down to sugars in the mouth under the action of digestive enzymes.

Another problem with targeting added sugar is the widely varying nutritional value of foods with added sugars. At one end of the scale soft drinks and some confectionery may contain virtually no nutrients other than sugar, but sugar-sweetened foods such as flavoured milk, fruity yoghurts and some breakfast cereals are nutrient-rich. Is it really wise to limit intake of these nutritious foods?


(Image source)

Wholegrains are enthusiastically embraced in the draft Dietary Guidelines and this is really the only measure of carbohydrate quality considered, other than added sugar. Wholegrains are recommended as being highly nutrient-dense and also protective against heart disease and type 2 diabetes. On the surface this appears to be scientifically sound and sensible advice, but the issues are not straightforward. Firstly, although nutrient density makes sense as a measure of the quality of carbohydrate-rich foods, many wholegrains are not highly nutrient-dense, as claimed. Secondly, many of the studies used to support the wholegrains recommendation were actually conducted using high fibre foods, suggesting that recommending high fibre cereal foods would be equally valid. Why recommend one but not the other?

A third concern is the lack of a plausible mechanism explaining the apparent protection of wholegrains against heart disease observed in some epidemiological studies. A study that went looking for the mechanism found nothing. Is the idea of the healthiness of wholegrains so appealing that nutritionists now accept the evidence they like and ignore the evidence they don’t?

Finally, many wholegrain foods have a high glycaemic index, which is gaining in importance as a measure of carbohydrate quality.

Glycaemic index

The glycaemic index or GI is a measure of the blood glucose-raising potential of a carbohydrate-rich food. Early interest in the GI focussed on its potential role in the diets of people with diabetes but more recent evidence suggests that GI has a broader role. GI is related to the risk for coronary heart disease – high GI foods appear to pose greater risk than saturated fat. And GI also has a role to play in weight management. A large European trial recently showed that the GI and protein content of the diet were important factors for maintaining weight loss.

One would have expected to see systematic literature reviews on these issues as part of the development of the new Dietary Guidelines, but not a single review relating to GI was conducted.

Trans fats

Trans fats have been introduced into the Australian Dietary Guidelines for the first time but one has to ask why? Again, no systematic literature review of trans fats and health was conducted so there was no evidence base. The text of Guidelines report contained just two sentences on trans fats which noted that intake of trans fats in Australia is low – half the maximum level recommended by the World Health Organization. Furthermore, three quarters of the trans fats in the Australian diet now come from ruminant fats (meat and dairy fat). As these fats are also rich in saturated fats, any recommendation to limit saturated fats will also serve to further lower trans fat intake. The problem of trans fats has been well and truly addressed over the last 15 years, so why bother alerting the general public to the issue now?

Fruit, vegetables and cancer

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The view that fruits and vegetables provide protection against cancer is widely held among nutritionists but is largely based on the results of old case-control studies, known for their bias. When this hypothesis was tested in large cohort studies the results were not encouraging. It is now clear that if fruits and vegetables have any effect on the risk for cancer it is very weak. In response, the World Cancer Research Fund downgraded the evidence of a link in its 2007 report. In the Dietary Guidelines for Americans, the whole section on fruit, vegetables and cancer was removed from the 2010 edition.

In the Dietary Guidelines process there may not have been any systematic literature reviews into saturated fat, trans fats or glycaemic index but there was a major evidence hunt for a link between fruit, vegetables, legumes and cancer. No less that 21 literature reviews were conducted. And the result? No ‘convincing’ or even ‘probable’ evidence of a link. But rather than follow the American lead and simply delete the issue, the Australian Dietary Guidelines doubled the amount of text devoted to this topic and painted a misleading picture suggesting that evidence for a protective effect of fruit and vegetables against cancer is building.

Is this evidence-based nutrition or something else?

47 thoughts on “Seven problems with the Dietary Guidelines

    • Tough question first up Jenna. Firstly, I’d get the principles right – healthy diets need more unsaturated fats in place of saturated fat, and ‘good’ carbohydrates in place of ‘bad’ carbohydrates. The trouble is, what constitutes good and bad carbohydrate is poorly defined at present. The sugar/complex carb approach is old hat – WHO says don’t use it – yet the latest Dietary Guidelines still say limit added sugar. ‘Wholegrain’ is good to a point, but some high fibre cereal products aren’t wholegrain. And it ignores GI. Nutrient density is another parameter. A colleague and I have developed a model of carb quality – the paper will be published in June. More later.
      Total fat intake should be moderate, not low.
      In relation to a food guide, the most important thing is to avoid any notion that unsaturated fat should be limited. It needs to be increased.

    • DEAR BILL…I enjoy reading your blogs and comments….and am equally as concerned as you. I became a dietitian because of all the GIT [bowel] cancers and diverticulosis in my family. Do keep up the good work keeping us all on our toes.

  1. Bill, what would your dietary guidelines for Australians look like if you were asked to provide some key recommendations?

    • Maria, as total sugar intake and total fat intake are largely unrelated to health outcomes I would be tempted to delete reference to these or advice intended to modify these. In relation to sugar, perhaps you could state ‘limit strong-nutrient-poor, sugar-sweetened foods’. But nutrient-poor is the important bit, not sugar. This would capture soft drinks, confectionery, biscuits, cakes and biscuits, but wouldn’t target foods like flavoured milk, fruity yoghurts and some breakfast cereals, which are nutrient-rich. Chocolate milk was banned from some schools in the US because it contained added sugar – just not thought through. But this is why the wording of dietary guidelines is so important.
      The Dietary Guidelines for Americans now encourage the replacement of saturated fat by unsaturated fat (not carbohydrate) and this is where the science is that. So low fat diets are history, at least in relation to the prevention of coronary heart disease. But the whole area was not even reviewed for the Dietary Guidelines. I’ll write something on this next week.
      In a nutshell, in addition to the usual messages about variety and moderation the focus should be on good fats and good carbohydrates (but we need to agree on what ‘good carbohydrates’ means).

  2. Hi Bill, interesting read. I was wondering if you could share which article from 2009 regarding the saturated fats and carbohydrates you are referring to. Thanks, Dorothy.

    • Hi Dorothy. The reference is: Jakobsen MU et al. Major types of dietary fat and risk of coronary heart disease: a pooled analysis of 11 cohort studies. Am J Clin Nutr 2009; 89: 1425-32.
      I’ll be discussing this issue in my next blog.

  3. Onya Bill. Added sugar/fructose is not a problem. Too bad about the mounting evidence that added sugar is a primary driving force of global obesity, diabetes and heart and kidney diseases. In any case, my first question is whether anything you and your “Low-GI is good” colleagues say on nutrition can be trusted, given the extremely poor standard of analysis revealed in the high-profile but seriously shonky “Australian Paradox” paper? ( ). Second, whatever happened to quality control of academic research at The University of Sydney University? Regards, Rory

    • Hi Rory. Firstly, I think current carbohydrate recommendations and current carbohydrate intakes are too high, so I don’t encourage the consumption of more carbohydrate from any source. I do question current policy settings that focus on added sugar and ignore GI (and nutrient density).
      I am a late convert to the ‘Low-GI is good’ camp, having sat on the fence for nearly 15 years. But as a large randomised controlled trial has demonstrated GI’s relevance to the maintenance of weight loss and further cohort data indicate GI affects coronary heart disease risk, I have (finally) shifted my position and now think that GI has to be considered.
      I can’t comment on the ‘Australian Paradox’ paper, which indicates that sugar intakes have declined in Australia as the obesity epidemic has unfolded, because I was not involved in it. However, if critics of this paper want to refute its findings they need to produce DATA to do so. Regards, Bill.

      • Bill, I give you credit for publishing my comment/questions, so thank you for that. As you may know, I have documented the authors errors in great detail (available on request) and that link above confirms that my analysis is strong. Indeed, the post-1980 uptrend in “sugar availability” (production less exports) completely invalidates the claim that sugar consumption has fallen substantially “over the past 30 years”, given the official data showing an uptrend in sugary imports. Similarly, the authors’ chart showing a 30% rise in sugary softdrinks also invalidates the claim. The authors must now know their preferred story is wrong, which I assume is why they invented the fiction in their rebuttal that nearly one-quarter of the available sugar (14/60 kg per person) is used for ethonal production, not food. Not prepared to acknowledge four large errors, the authors chose to make a fifth. So University of Sydney’s quality control on academic output seems to be MIA?

        • Hi Rory. Two points. Firstly, the percentage of carbohydrate as sugars in the US diet has been falling for three decades – the increase in total carbohydrate intake has primarily been in the form of starch (1) – so it’s not unreasonable to think that something similar may be happening in Australia. Your claim that “… added sugar is a primary driving force of global obesity, diabetes and heart and kidney diseases …” is hard to justify. It would be more accurate to claim that energy intake or total carbohydrate or starch is the driving force.
          The distinction between sugars and complex carbohydrates (starch) is an artificial one. Didn’t the WHO ask us not to do this over a decade ago? The metabolic consequences of overeating starch are just as bad as those for overeating sugar. The current panic about sugar is a distraction from more important issues. Regards, Bill
          1. Chun, OK, Chung CE, Wang Y, Padgitt A, Song WO. Changes in intakes of total and added sugars and their contribution to energy intake in the U.S. Nutrients 2010 Aug 2(8):834-54.

  4. With havin so much written content do you ever run into any problems of plagorism or copyright infringement? My blog has a lot of exclusive content I’ve either authored myself or outsourced but it appears a lot of it is popping it up all over the web without my authorization. Do you know any methods to help reduce content from being stolen? I’d genuinely appreciate it.

    • Hello Connie. If people borrow some of your arguments or your text the expectation is that they will acknowledge the original source. Apparently this is not the norm. For me, it doesn’t matter. If I encourage the dissemination of science-based nutrition information I will have achieved my objective. Regards, Bill

  5. Just a comment on the dietary guidelines being influenced by environmental concerns.

    I am all for initiatives which help reduce fossil fuel use, and have put this in place myself (eg. upgrading a car to one which uses about 1/2 the fuel).

    However, I question how much influence it should have over the dietary guidelines.

    If nutrition research demonstrates something which may have the potential for an environmental impact (eg. increasing fish consumption), then surely the overall nutritional impact should be what features in dietary guidelines.

    Perhaps a segment of ‘environmental considerations’ could be added at the end, in much the same way a segment on reducing chronic disease risk was added to the NRV document.

    As I see it – the guidelines should be made on nutritional considerations alone. If that conflicts with or has impacts on environmental considerations, then we need to work towards making those impacts more sustainable (eg. looking at ways farmed fish have have less environmental impact etc.), rather than adjusting the dietary guidelines.

    Any thoughts there?

    • Thanks for your comments Paul. I doubt that anyone disputes that environmental considerations are important, but there does seem to be a push on to modify healthy eating advice to meet environmental goals.
      When the first modelling was conducted for the new Dietary Guidelines restrictions were placed on meat, dairy products, eggs and fish, all on environmental grounds. The concern, expressed by many, was that nutritional health was being compromised: With about a third of young women showing some degree of iron deficiency, why would you limit their red meat intake? With calcium being a limiting nutrient in the diets of teenage girls, why would you limit dairy products? With increasing vitamin D insufficiency in Australia, why limit all major dietary sources of vitamin D? And why limit all major sources of long-chain omega 3? Fortunately, wise heads prevailed in the end.
      Eating for health and eating to minimise environmental impacts are two different things. They may be in direct conflict – your fish example is a good one. But the nutritionist’s role is to argue the health case. Hopefully a compromise can be found that reconciles nutritional and environmental concerns e.g. by improved fish farming rather than the damaging hunter-gather approach of traditional fishing. Regards, Bill

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    • Eveline, you are welcome to insert part of my blogs on your personal web site, provided the original source is acknowledged. Regards, Bill

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