On Friday, the results from the first comprehensive survey of the dietary habits of Australians since 1995 was released, measured as part of the 2011-2013 Australian Health Survey. While the diets of children and adolescents had been measured in 2007, this is the first time since the 1995 National Nutrition Survey that the diets of adult Australians has been assessed. This is quite astounding when you consider that poor diet is a major risk factor in the epidemic of chronic disease facing Australians. Many other countries monitor their population’s dietary habits routinely every few years; we do not.
Diet is a complex behaviour to measure. We eat many different foods every day, in various combinations and patterns. Unlike other health behaviours such as physical activity that are also difficult to measure, we have yet to develop any nifty electronic devices that can measure everything that someone puts in their mouth.
The survey, like previous ones in Australia and also used in most other countries, relies on what is known as a “24 hour recall”, meaning that each person is interviewed and asked to remember what was eaten on the previous day. This method has been developed and refined over many years, and includes many techniques and tricks to help people remember and report the foods eaten. It is considered one of the best methods (the “gold-standard”).
A strength of the 24-recall method is that people can’t change their behaviour, which is a common problem with keeping diaries of food consumption. With a large enough sample of people, and completed on two days, it can tell us about what is being eaten at the population level.
So what did the results so far tell us? The major headlines reported that adolescent boys and young males have the worst diets across the population. This is supported by data showing that among 14-18 year old boys, approximately 41% of their energy intake comes from “discretionary foods” (foods and drinks not necessary to provide the nutrients the body needs, and usually high in saturated fats, sugars, salt and/or alcohol).
Other data from the survey shows that soft drink consumption is high in this age group, with 51% reporting having them on the day of the survey while 78% reported having cereal-based products, such as cakes, biscuits and pastries. Young adult males aged 19-30 years are not far behind with 36% of energy coming from discretionary foods, and 44% of them consuming soft drink. While diets of young males appear poor, adolescent girls and young women do not fare much better.
These results in young people are concerning. We know that diets established in adolescence track through to adulthood. Other results from the Australian Health Survey show that even among young adults, the prevalence of diet-related risk factors for the major chronic diseases, such as obesity and dyslipidaemia, is surprisingly high.
Young adults are also a particularly important target group for nutrition promotion messages, given the potential impact on the next generation. Obesity among women of child-bearing age is a significant concern due to the acute and chronic health impacts on both mother and child, while parents are a major influence on the health behaviours of their children.
These first results are intriguing, but they are only the start as much more needs to be done to really understand the data. Further work will need to be done to compare what is eaten against the Australian Dietary Guidelines and the Recommended Dietary Intakes.
This analysis will need to use the two days of dietary recall that were collected in a large proportion of the survey participants. This will allow consideration of daily variations in dietary consumption, and will provide the necessary data to estimate the proportion of participants with dietary intakes above or below specific cut-points and recommendations. We will also need rigorous comparisons with the previous survey in 1995 to understand whether there are changes occurring in the population or in particular subgroups.
Other important questions also remain to be examined. For example, we know that diets in people with lower levels of education or with lower incomes are usually worse that those with higher education or income levels. This type of analysis hasn’t been presented yet, but an important question is not just whether these differentials still exist, but whether they have worsened over time or if there have been improvements.
This national survey will provide much needed, and long overdue evidence on the current dietary habits of the Australian population. Data of this nature is necessary for development and evaluation of a range of food and nutrition-related guidelines and policies. It will be used by a wide range of health agencies in Australia to develop and implement evidence-based policies and programs. These activities require evidence relevant to local context, as we can’t simply rely on overseas data given the local variations in food supply and the different way food is consumed.
While this new survey is extremely valuable, we still need an ongoing national system for nutrition monitoring and surveillance.