The urgency of monitoring salt consumption and its effects in Aboriginal and Torres Strait Islander Australians

To the Editor: There is convincing evidence that high salt diets are linked to elevated blood pressure — a major risk factor for chronic diseases.1 Premature mortality due to chronic diseases is a major contributor to the life expectancy gap between Indigenous and non-Indigenous Australians.2 Although much has been written about the health benefits of a traditional hunter-gatherer diet and the detrimental effects of colonisation on diet and exercise patterns,3 we know little about how colonisation has affected salt intake among Indigenous Australians.

Currently in Australia, most efforts to prevent disease caused by high blood pressure focus on the clinical management of hypertension. Such programs can only affect individuals identified and treated for high blood pressure. In population terms, a small proportion of the total blood pressure-related disease burden is adequately addressed by this approach.4 Salt reduction programs, on the other hand, have the potential to address much more of the disease burden. A modest reduction in salt intake has been found to have a significant blood pressure-lowering effect.5 Furthermore, salt reduction programs that are implemented by modifications to the food supply have the potential to prevent disease at a very low cost.6

Salt consumption data in Australia are limited. A recent study in regional New South Wales, Drop the Salt Lithgow, confirmed that Australians are eating too much salt. The average salt intake in this Australian population was 9 g/day (Mary-Anne Land, Research Assistant, The George Institute for Global Health, unpublished data), which is 50% higher than the upper limit of 6 g/day recommended by the National Health and Medical Research Council.7 Unfortunately, this study only captured a small number of Indigenous Australians.

We suggest expanding the scope of this research to Indigenous communities in New South Wales (by adapting the methods used in Drop the Salt Lithgow) to determine the types of food bought, prepared and eaten that have high levels of salt. This would involve: collecting baseline data on salt intake (by measuring 24-hour urinary sodium excretion) and dietary sources of salt (via 24-hour dietary recall questionnaires); implementing a salt-reduction program; and collecting follow-up data on dietary sources of salt (by repeat questionnaires). Surveying 500 people at baseline and follow-up would provide power to detect a difference in salt consumption that would translate to real differences in individual and population health.

We believe that research aimed at recruiting a community-based sample of Indigenous adults to precisely and reliably measure salt intake and to better understand behaviours that underpin dietary patterns is a public health priority.