It’s always difficult to capture in a few words the changing state of modern nutrition, the implications of new scientific findings, the wisdom of calls for change to dietary advice and the conservative response. Yet Professor Jennie Brand-Miller from the University of Sydney managed to do it at a recent food labelling conference in a presentation titled ‘Old nutrition, new 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.
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.
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?
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.