Consumer knowledge and attitudes to salt intake and labelled salt information

Abstract

The objective of this study was to investigate consumers’ knowledge of health risks of high salt intake and frequency of use and understanding of labelled salt information. We conducted a cross-sectional survey in shopping centres within Metropolitan Melbourne. A sample of 493 subjects was recruited. The questionnaire assessed salt related shopping behaviours, attitudes to salt intake and health and their ability to interpret labelled sodium information. Four hundred and seventy four valid surveys were collected (65% female, 64% being the main shopper). Most participants knew of the relationship between salt intake and high blood pressure (88%). Sixty five percent of participants were unable to correctly identify the relationship between salt and sodium. Sixty nine percent reported reading the salt content of food products when shopping. Salt label usage was significantly related to shoppers concern about the amount of salt in their diet and the belief that their health could improve by lowering salt intake. Approximately half of the sample was unable to accurately use labelled sodium information to pick low salt options. Raising consumer awareness of the health risks associated with high salt consumption may increase salt label usage and purchases of low salt foods. However, for food labels to be effective in helping consumers select low salt foods a more ‘user friendly’ labelling format is needed.

Introduction

There is conclusive evidence that a high dietary salt intake is associated with the development of high blood pressure, which is a major risk factor in the development of cardiovascular disease (SACN, 2003, WHO, 2007). The World Health Organization (WHO) estimates that globally 62% of cerebrovascular disease and 49% of ischaemic heart disease are due to elevated blood pressure (WHO, 2007). The estimated daily salt consumption of adults in the United Kingdom (UK) and Australia is approximately 9 g (Beard et al., 1997, FSA, 2008b, Notowidjojo and Truswell, 1993), well in excess of the maximum 5 g per day recommended by the WHO and the 6 g per day recommended by the National Heart Foundation (NHF, 2006, WHO, 2007). It has been estimated in Australia that 7% and 25% of ischaemic heart disease in men and women, respectively and 15% and 45% of ischaemic stroke in men and women, respectively, are due to high blood pressure (Martiniuk et al., 2007). It has been calculated that implemented over a 10 year period, a 15% reduction in population salt consumption across the 23 countries that account for 80% of chronic disease burden in the developing world could prevent 8.5 million deaths (Asaria, Chisholm, Mathers, Ezzati, & Beaglehole, 2007).

To reduce population salt consumption the WHO recommends the development of supportive environments that promote healthy food choices (WHO, 2007). This would be achievable through the use of a clear, concise and consistent nutrition labelling system on food products (WHO, 2007). Current labelling regulations in Australia require food products to display the sodium content of the food per serve and per 100 g within the nutrition information panel (NIP) and the salt content is not provided (FSANZ, 2007a). As defined by Food Standards Australia New Zealand (FSANZ) a manufacturer can label a food as ‘low salt’ if the food contains less than 120 mg of sodium per 100 g of the food, with the sodium information displayed in the NIP. Other claims such as ‘reduced salt’ are permitted if the food has at least 25% less sodium than the comparative reference food (FSANZ, 2007b). In contrast in the UK food can be voluntarily labelled with the salt content and the salt content forms the basis of educational approaches to reduce dietary salt intake. Many manufactures in the UK and Europe now include the salt equivalent figure on food labels (Bussell, Hunt, & Federation, 2007). Many Australian food manufactures now additionally include front of pack (FoP) signposting in the form of the percentage daily intake (%DI) label which provides recommendations of intake for energy, protein, fat, saturated fat, carbohydrate, total sugars, fibre and sodium (FSANZ, 2007c).

Many consumers report using nutrition food labels when shopping and a number of studies have concluded that increased label use is associated with positive dietary outcomes, such as reduced fat (Kristal and Patterson, 2001, Neuhouser et al., 1999, Satia et al., 2005) and sugar consumption (Weaver & Finke, 2003). In comparison to other nutrients such as fat and sugar the number of consumers who report reading the salt content of food products is lower (FSA, 2008a, Marshall et al., 2007, Patterson et al., 2001, Scott and Worsley, 1997). Public health messages regarding fat intake and cardiovascular disease and high-energy diets and obesity have been widespread in most Western populations. In comparison salt has received less attention and thus may explain the prioritizing for reducing other nutrients such as fat in the diet.

Few studies have examined the consumer's ability to interpret nutrition information regarding salt labelled on food products. Consistently across studies consumers criticize the use of scientific terminology, i.e. sodium, on nutrition food labels (Grunert and Wills, 2007, Patterson et al., 2001, Patterson et al., 2003, Scott and Worsley, 1997). In addition many consumers lack the knowledge to convert sodium levels into salt levels and thus cannot accurately interpret sodium information (Gilbey and Fifield, 2006, Marshall et al., 2007). Overall consumers have a poor understanding of the relationship between salt and sodium (AWASH, 2007, CASH, 2003, EHN, 2003), therefore it is speculated that many Australian shoppers would have difficulty in using the sodium content information currently labelled on food products to interpret salt content.

In developing labelling formats that enable the consumer to choose low sodium options it is necessary to establish how shoppers use and interpret the sodium information on food products and if they understand the relationship between salt and sodium. The aims of this study were to determine consumer knowledge of the relationship between salt and sodium and the health risks of high sodium intake; the frequency of consumer use of sodium labelling on food products and the influence this has on shopping behaviour; and assess consumers’ ability to interpret the sodium information on Australian food labels.