26th September 2014, Volume 127 Number 1403

Helen Eyles, Cliona Ni Mhurchu

Population diets are commonly monitored using national nutrition surveys that employ traditional dietary assessment methods such as 24-hour dietary recalls. However, national nutrition surveys typically occur only every 10 years or so in New Zealand, largely because of high costs. Moreover, traditional dietary assessment methods such as the 24-hour recalls are prone to bias and measurement errors due to reliance on self-report.1,2 An alternative is to use electronic food purchase data linked with information on the nutrient composition of foods, as has been done in the United Kingdom,3,4 and for a small number of nutrition intervention studies, including in New Zealand.5,6

Although food purchase data are usually collected at household rather than individual level, they are a good proxy for food and nutrient intakes.7 Furthermore, their objective nature means they are less affected by individual biases.

In New Zealand, Nielsen (a market research company) collects electronic food purchase data using their Homescan®panel, a national, geographically and demographically representative panel of ~2,500 New Zealand households who scan all foods and beverages purchased for consumption in the home. 8 The Nielsen Homescan® panel has been in existence for 16 years, and the weighted data represent ~75% of the ~$11 billion annual total retail grocery sales in New Zealand.

Since 2011, The National Institute for Health Innovation (NIHI) at the University of Auckland has been undertaking annual systematic surveys of the nutrient composition of packaged foods available in New Zealand supermarkets and fast food restaurants (the Nutritrack database).9 We (NIHI) recently combined Nielsen Homescan® and Nutritrack data to (1) assess population exposure to sodium, saturated fat, and sugar in New Zealand, and (2) identify key opportunities for reformulation of processed foods with the largest potential population health benefits.

Analyses were undertaken using data on more than 16,800 packaged, processed New Zealand food and non-alcoholic beverage products ($3.7 billion total annual sales). Crude and sales-weighted means (weighted by number of units sold) were calculated overall and by food category, and major contributors to household purchases of sodium, saturated fat, and sugar were identified.

Figure 1 shows the proportional contribution major processed food groups make to sodium, saturated fat, and sugar purchases in New Zealand. Specific food categories within those food groups contributing most to nutrient purchases are where the largest population health gains could be made via reformulation and/or reduced consumption (Table 1).

The full report is available on request from the lead author (HE).


Figure 1. Percentage contribution of specific food groups to annual purchases of sodium, saturated fat, and sugar

fig1


 

Table 1. Percentage contribution of specific food categories to annual purchases of sodium, saturated fat, and sugar

table

 

Our findings align with analyses of Australian and United Kingdom processed foods.3,4 Although New Zealand food manufacturers have already removed some sodium from bread,10 bread remains the single biggest source of dietary sodium and hence a primary target for continued reformulation, intervention, and policy. Secondary yet still important targets for sodium reduction are processed meat, savoury sauces, cheese, and edible oils (margarine, butter, and spreads).

Corresponding targets for saturated fat reduction are edible oils, cheese, and biscuits, which combined account for 48% of saturated fat purchased by New Zealand households. In order for New Zealanders to meet the new suggested World Health Organization (WHO) guideline for sugar intake,11 food manufacturers should work on reduction of sugar in biscuits, chocolate and sweets, and soft drinks, particularly as these are foods consumed in high quantities by New Zealand children.12

Increased consumer awareness via targeted nutrition education campaigns and policies is also important, especially as plain sugar, which is unlikely to be reformulated, is the top contributor to sugar purchases in New Zealand.

These analyses illustrate the potential of electronic household food purchase data to guide important improvements in population diets. Moreover, they show important potential as a way of objectively monitoring food and nutrient availability and purchases between infrequent national nutrition surveys.

Linked sales and food composition data also offer unique opportunities to identify where healthier reformulation of specific processed food products is likely to have the largest population health benefits. Finally, such data could be used to provide independent evaluation of the impact of industry initiatives, national nutrition interventions, and policies to improve the processed food supply.

Author Information

Helen Eyles
Research Fellow, National Institute for Health Innovation, University of Auckland
Auckland, New Zealand

Cliona Ni Mhurchu
Programme Leader – Nutrition, National Institute for Health Innovation, University of Auckland
Auckland, New Zealand

Acknowledgements

Funding from an HRC programme grant (Ref #13/724) contributes to the NutriSales project. HE holds a Heart Foundation of New Zealand research fellowship (Ref #1463).

Correspondence

h.eyles@auckland.ac.nz

References

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2. Winkler JT. Nutritional survey data are inaccurate. Brit Med J. 2014;348:g3204.

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11. World Health Organization. WHO opens public consultation on draft sugars guideline. Accessed 3rd June 2014. Available: http://www.who.int/mediacentre/news/notes/2014/consultation-sugar-guideline/en/ 2014

12. Ministry of Health. NZ Food NZ Children: Key results of the 2002 National Children's Nutrition Survey. Wellington: Ministry of Health; 2003.