Old nutrition

Brand-Miller began by stating: The old nutrition goes like this ….

• Foods can be dissected into macronutrients
• Saturated fat is the main dietary risk factor for cardiovascular disease
• A low fat diet is best for prevention of obesity, diabetes and cardiovascular disease
• “Eat a diet that is low in fat and high in complex carbohydrate”
• “Eat plenty of cereals, breads, rice, pasta and noodles, preferably wholegrain”

And then she took old nutrition apart, highlighting how the nutrition landscape had changed over the past decade or so:

• Large, long-term, randomised controlled trials had showed low fat dietary advice did not prevent heart disease, stroke, type 2 diabetes, breast cancer or colon cancer.

• The prevalence of obesity and type 2 diabetes had continued to increase, despite the adoption of lower fat diets in Australia and the United States.

• In relation to heart disease risk, some carbohydrates were worse than saturated fat. In particular, high glycaemic index carbohydrates were linked to higher risk of cardiovascular disease, as well as higher risk for diabetes and some cancers.

• Higher fat, Mediterranean-style diets produced better weight control and cardiovascular outcomes than low fat diets.

• When compared head-to-head in high quality randomised controlled trials, energy-dense, high protein, very low carbohydrate diets were associated with faster weight loss and better cardiovascular risk factors than low fat diets.

• Low glycaemic index/low glycemic load diets were associated with improved diabetes control, prevention of weight re-gain and reduced risk of type 2 diabetes.

Ouch! That hurt!

In explaining the shortcomings of the old nutrition and the benefits of alternative approaches Brand-Miller argued that foods’ effects on postprandial glycaemia and insulinemia were central. Here was a unifying mechanism that encompassed effects on blood lipids, oxidative stress, markers of inflammation and, importantly, satiation and appetite control.

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New nutrition

Warming to her task Brand-Miller continued: So the new nutrition goes something like this …

• Low fat dietary advice has been unhelpful. It is consistently associated with weight re-gain. It does not reduce the risk of chronic disease.
• We should pay more attention to protein.
• We should pay more attention to the quality of carbohydrate sources. We need to swap high GI carbohydrate for low GI. 
• Unlike Americans, Australians don’t eat too much sugar.
• There is a range of healthy macronutrient ratios.
• High fat Mediterranean diets, higher protein diets and low GI diets are all helpful .

Brand-Miller argued that this advice offers flexibility and moderation; it accommodates cultural and ethnic differences; and it is behaviourally more sustainable. She stated that some authorities are already embracing the new nutrition, including the Institute of Medicine and the Joslin Diabetes Clinic in the United States, which have begun to recommend lower carbohydrate and higher protein intakes.

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Food labelling: new system, old nutrition

Most dietitians and nutritionists would be aware that a new front-of-pack food labelling system is to be introduced in Australia. Similar to the energy star rating system on electrical goods, the easy-to-interpret labels are intended to help the general public quickly assess the nutritional value of foods and identify healthier choices. Of course, whether the scheme actually provides meaningful guidance to the consumers will depend on the criteria used to assess the nutritional quality of foods.

Brand-Miller argued that the algorithm underpinning the new star system is based on old nutrition, highlighted by the focus on energy, fat, salt and sugar. She reeled off a string of anomalies: lentils and liquorice have the same energy density; nuts are more energy dense than French fries; dried fruit is full of sugar; and soft drinks are low in sodium.

In an aside, Brand-Miller said if breast milk were sold in the dairy compartment of the supermarket it would be docked a star because of its sugar content – human milk has the highest sugar content of any mammalian milk. Isn’t it interesting how Mother Nature knows how to ensure that infants drink their milk and thrive but humans are criticised when they use the same strategy with older children, sweetening milk to improve its palatability?

Surprisingly, in spite of embracing old nutrition, the star food labelling system virtually ignores micronutrients. Isn’t the provision of essential nutrients is the fundamental nutritional role of food? Brand-Miller argued that any star system should use Adam Drewnowski’s nutritional quality index as an essential component.

Starch: goodness by default

For Brand-Miller, a major concern about the proposed food labelling system is the healthiness afforded to starch, which is achieved by default i.e. by what it’s not – fat and sugars. The idea that starch is protective relative to fat, or even saturated fat, is prehistoric. Pooled data from 11 large cohort studies shows that carbohydrate and saturated fat pose the same risk for coronary heart disease. In 2010, a European study was published showing that high GI carbohydrates posed greater risk than saturated fat, reinforcing the concern about glycaemic load flowing from studies in the United States. Many starchy foods, even some wholegrains, have high GIs. Seriously, how can a food labelling system encourage less saturated fat and more high GI starchy foods? It’s as logical as recommending more saturated fat and less high GI foods.

Rating starch above sugars is also fraught. In a previous post I highlighted that the relative amounts of sugar and starch in Australian breakfast cereals are unrelated to nutrient density, energy density or glycaemic index. In other words, in these starch-based foods the amount of sugar present is not related to any property or mechanism that might conceivably affect health. Yet the new star food labelling system will separate breakfast cereals on the basis of sugar – healthy eating advice that won’t affect health. Sounds a bit like the old nutrition, doesn’t it?

Policy failure

We would have had more insight into these issues if the National Health & Medical Research Council had commissioned systematic literature reviews into saturated fat and glycaemic index/load for the latest dietary guidelines, but it did not. As far as I know the NHMRC has never systematically reviewed the evidence relating to GI in the 30 years that the concept has been around. With the proposed food labelling system we are now paying the price for this policy failure.

If the responsible health authorities refuse to even consider some of the scientific literature dietary advice will never change. Perhaps that’s the idea.

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Health authorities around the world have struggled to find effective ways of addressing the obesity epidemic. One recommended strategy is the introduction of traffic light labelling of food products to make it easier for the general public to choose healthier foods in the supermarket. It is argued that healthier food choices would not only tackle the obesity issue but could also address many other diet-related chronic diseases. Sounds good in theory but it simply won’t work.

What is traffic light labelling?

Currently nutrition information on food packaging appears in the nutrition information panel where amounts of various nutrients per 100g of product or per serve are listed. It’s all very quantitative – lots of numbers – and for many people it’s just too technical and difficult to understand. The rationale behind traffic light labelling is to interpret the current nutrition information for the public and give it some meaning. Green, amber or red traffic lights would be assigned to ‘nutrients of concern’ such as fat, saturated fat, sugar and salt to indicate whether a product was low, medium or high in these nutrients. It is argued that with better communication of the nutrition information the public would make healthier food choices.

If you are interested in the argument in favour of traffic light labelling take a look at the Australian Medical Association’s position papers on the issue.

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Assumptions

There appear to be three assumptions underpinning the argument in favour of traffic light food labelling: (1) An unhealthy food can be defined in terms of its content of total fat, saturated fat, sugar and sodium, (2) people become overweight because they eat unhealthy food, and (3) communicating these nutrient details to the general public will change food choice. All three assumptions are debatable but let’s focus on the first.

There is a fundamental problem with the nutrition criteria that have been included in the proposed traffic light model – total fat, saturated fat, sugar and sodium. Although some of these are linked to health outcomes, others are only useful for assessing certain food groups and some are totally useless. Let’s start with a useless one.

Total fat as a criterion

The idea that the total fat content of a food is a measure of its healthiness is one of nutrition’s great anachronisms. Thirty years ago it was hypothesised that total fat intake was linked to health outcomes – high fat intakes possibly increasing the risk for breast cancer, bowel cancer, coronary heart disease and obesity. Large prospective cohort studies were commenced to test the hypothesis but the results were overwhelmingly negative in relation to all of these conditions.

Image: Walter Willett: source

Here is how Walter Willett, professor of nutrition and medicine at the Harvard School of Public Health, summed up his presentation on fat and health at a conference in Boston at the end of 2010: In conclusion, let me reiterate that diets with a lower percentage of energy from fat do not reduce the risk of heart disease, diabetes, cancer, or adiposity. For some people, a reduction in total fat can actually be harmful if healthful fats are preferentially reduced. We should just clean up our dietary guidelines and remove any reference to percentage of energy from fat …

Think about this. If the fat content of the whole diet is not related to any outcome of public health significance, what possible purpose could be served by highlighting the fat content of an individual food?

What about saturated fat?

Saturated fat is a useful criterion for assessing fat-rich foods such as vegetable oils, margarines, salad dressings, dairy foods and meats. But it is totally inappropriate for assessing carbohydrate-rich foods based on, say, potato, cereal or fruits. Saturated fat and carbohydrate confer the same risk for coronary heart disease. Giving a green light on saturated fat to a carbohydrate-rich food would not only be wrong-headed scientifically it would send a misleading message to the general public.

Heart disease risk falls when saturated fat is replaced by unsaturated fats. This is the exchange that food labelling needs to encourage, not just lowering saturated fat.

Sugar

In an earlier post we noted that health authorities in both the United States and Europe have been unable to set an upper limit for sugar consumption for the prevention of any chronic disease, including obesity, so we won’t go over this old ground again. But the situation is analogous to that of total fat: if the sugar content of the whole diet has negligible effect on health, what is the logic in focussing on the sugar content of an individual food?

The muesli example

A good example of how focussing on fat and sugar can send misleading and confusing messages was a review of 159 mueslis in the Australian Consumers Association’s Choice magazine published last year. Much of the information presented in the article is factual, but the accompanying press release was titled ‘Spoonful of muesli may be mouthful of sugar and fat’. The media loved it – it was one of those ‘you think it’s good for you but it’s really not’ stories. But it was very misleading.

The article noted that much of the fat in the mueslis actually came from nuts and much of the sugar came from dried fruit. So in this case the fat and sugar in the mueslis were markers of nutritious ingredients – nuts and fruits. So what was all the fuss about? How would Choice magazine advise a muesli manufacturer to improve the nutritional quality of its products? Cut back on the nuts? Cut back on the fruits?

Sugar and total fat are simply not useful measures of the healthiness of foods and diets. Highlighting their content in foods does not enable consumers to make healthier choices.

Would traffic lights really make decision making easier?

While you are looking at the Choice muesli article run you eye down the long table of mueslis, all with traffic light-type symbols for total fat, saturated fat, sugar and sodium. The first thing you notice is that none of the products gets four green lights. And none of them gets four red lights, so there is no clear endorsement or rejection of any of the mueslis. In fact, the majority of products have a combination of red, amber and green lights – the ultimate mixed message.

How is this supposed to help consumers make a healthy choice? If you were in your car at the traffic lights and the red, amber and green lights all shone at once, what would you do?

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