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Food consumption data used in dietary exposure assessments

(May 2014)

National nutrition surveys (NNSs) provide detailed, national data on consumption of foods, beverages and, in some cases, dietary supplements. This quantitative data on consumption is essential to the type of dietary exposure assessments we generally do at FSANZ.

The following national nutrition surveys from Australia and New Zealand are used by FSANZ to estimate food consumption:

1995 Australian National Nutrition Survey

  • 13,858 respondents
  • 2 years and above
  • 24-hour recall – one recall per respondent [1]
  • 2nd 24-hour recall –10% of respondents
  • Food frequency questionnaire for 12 years and above
  • Short questions on food consumption patterns
  • 13 month duration
  • Multi-stage area sampling based on census districts

1997 New Zealand National Nutrition Survey for adults

  • 4,636 respondents
  • 15 years and above
  • 24-hour recall – one recall per respondent
  • 2nd 24-hour recall – 15% of respondents
  • Food frequency questionnaire
  • Short questions on food consumption patterns
  • 12 month duration
  • Stratified sampling

2002 New Zealand Children's Nutrition Survey

  • 3,275 respondents
  • 5-14 years
  • 24-hour recall – one recall per respondent
  • 2nd 24-hour recall –15% of respondents
  • Quantified dietary supplement consumption
  • 10 month duration
  • School based sampling with non-proportional samples

2007 Australian National Children’s Nutrition & Physical Activity Survey (ANCNPAS)

  • 4,487 respondents 
  • 2-16 years
  • Two 24-hour recalls – all respondents
  • Short questions on food consumption patterns
  • Quantified dietary supplement consumption
  • 7 month duration
  • Stratified sampling with non-proportional samples

We expect the following consumption data to become available in Harvest in 2014-16:

2008-09 New Zealand Adult Nutrition Survey

  • 4,721 respondents
  • 15 years and above
  • 24-hour recall – one recall per respondent
  • 2nd 24-hour recall – 25% of respondents
  • Short questions on dietary habits and dietary supplements 
  • 12 month duration 
  • Stratified sampling with non-proportional samples

2011-13 Australian Health Survey (AHS): 2011-12 National Nutrition and Physical Activity Survey (NNPAS) (general wave)

  • 12,153 respondents 
  • 2 years and above
  • 24-hour recall – one recall per respondent
  • 2nd 24-hour recall – 63% of respondents
  • 13 month duration
  • Stratified sampling with non-proportional samples

2012-13 National Aboriginal and Torres Strait Islander Nutrition and Physical Activity Survey​

  • Approximately 3,000 respondents
  • Whole population
  • 24-hour recall – one recall per respondent
  • Approximately 12 month duration

Why not use more current consumption data?

We need extensive quantitative data to conduct detailed dietary exposure assessments. Until recently, the 1995 Australian and 1997 New Zealand NNS were the most recent comprehensive sets of quantitative data on food consumption patterns available to FSANZ for most of the Australian and New Zealand populations, apart from the children’s data that became available for exposure assessments in 2009 (2007 ANCNPAS, 2002 NZ children’s NNS). Conducting dietary modelling based on these food consumption data provides the best estimate currently available of dietary exposure across our populations because they are national studies, across wide age ranges, of all foods and beverages consumed. However, by 2015 FSANZ will have incorporated new data sets for both Australia (2011‒12 NNPAS) and New Zealand (2008‒09 adults NNS) for use in our dietary exposure assessments.
 
While older NNSs may not include information about food products now available in the market, for staple foods such as breads, cereals, milk etc., the data derived from these surveys are likely to be still representative today at a broad food group level. For some product segments, NNS data from the 1990s may not be appropriate for use in a dietary exposure assessment (e.g. of bottled water). In these cases, FSANZ may modify its modelling technique (e.g. through the selection of a similar food as a surrogate) or seek additional consumption data.
 
Additional qualitative data on food consumption are sometimes available and these may help us interpret food consumption data and verify assessments carried out using the NNS on a case-by-case basis.

What other data are used in dietary exposure and intake assessments?

Whether or not FSANZ uses additional data in a dietary exposure or intake assessment depends on a number of factors, including the purpose of the assessment, the nature of the hazard and risk, the quantity and quality of data available, and the existence and type of the relevant health-based guidance value. We may use a variety of data sources such as:
  • food frequency questionnaires
  • consumer research
  • published scientific research
  • market share data and retail sales figures
  • data supplied with applications to change the Food Standards Code or submissions associated with these applications.

Limitations of national nutrition survey data

Dietary exposure estimates based on NNS food consumption data provides the best estimate of actual consumption of a food and the resulting estimated dietary intake of a nutrient for the population or dietary exposure to a food chemical. However, NNS data do have their limitations. These limitations relate to the age of the data and the changes in eating patterns that may have occurred since the data were collected. Generally, consumption of staple foods such as fruit, vegetables, meat, dairy products and cereal products, which make up the majority of most people’s diet, appears to have been fairly stable between the 1983, 1985 and 1995 Australian NNSs, although there were a few notable changes over this time, including small increases in cereals and fish consumption among adults. However there is greater uncertainty when assessing consumption of foods introduced to the market since these NNSs were conducted, or for which there may have been changes in food consumption patterns.
 
Over time, there may also be changes to the ways manufacturers and retailers make and present foods for sale. Since the data were collected for the 1995 Australian, and 1997 and 2002 New Zealand NNSs, there have been significant changes to the Food Standards Code to allow more innovation in the food industry. As a consequence, another limitation of the dietary exposure assessment is that some of the foods that are currently available in the food supply were either not available or were not as commonly available when previous surveys were done. For example since the data were collected for these surveys, there has been an increase in the range of products that are fortified with nutrients. For some dietary exposure assessments, these changes in the food supply will be particularly relevant and we will address these as far as possible in our assessment, and note these and where significant data limitations exist in our reports.
 
Challenges in interpreting data can result from using a single 24-hour period to represent long-term eating patterns. This is because daily food consumption amounts for occasionally consumed foods based on 24-hour food consumption data tend to be higher than daily food consumption amounts for those foods based on a longer period of time. As a result it is possible to overestimate the potential exposure of high consumers, which may lead to the imposition of overly restrictive risk management measures. Our web page protecting high consumers, explores this further.
 
While the results of NNSs can be used to describe the usual nutrient intake of groups of people by calculating a second day adjusted intake, they cannot be used to describe the usual intake of an individual. In particular, they cannot be used to predict how consumers will change their eating patterns as a result of an external influence such as the availability of a new type of food.
 
There are some foods reported in the NNSs for which the number of people who ate the food is too few to allow a reliable assessment of population-wide consumption patterns. In these cases it may be necessary to select a similar, more widely consumed food as a proxy. For example, lemons could be selected as a proxy food for limes. There may also be insufficient consumers of a food in a certain age group (e.g. young children).
 
The NNSs were not designed to capture information on food consumption during pregnancy, so we are not able to model dietary exposure in pregnant women. As an alternative, FSANZ will generally model dietary exposure for women of child-bearing age (16-44 years) as a proxy for pregnancy.
 
No NNS data are available for New Zealand children aged 2-4 years. Dietary exposure assessments produced for Australian 2-4 year olds will be assumed to be applicable to New Zealand children, unless there is clear evidence to the contrary.

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