Table 4 Input parameters relating to the interventions costs

Salt substitution at 59 %

The cost was that of a new law for NZ, which was based on the average cost of new act [67] at NZ$ 3,680,000 in 2011 dollars (these NZ$ dollar values are detailed in an online report [68]). Salt substitutes can cost around 50 % more than normal salt [16]. However, as salt is currently extremely cheap (e.g., wholesale prices of $0.7 per kg in NZ) the extra cost for salt from processed food would be under 1 cent per day (for the average NZ intake of 9 g salt per day) and so was ignored.

It was considered out-of-scope given our health system perspective to consider reformulation costs and costs associated with package labelling changes. Our approach is also in accord with past NZ laws relating to food labelling, alcohol labelling and tobacco labelling in that manufacturers are not compensated for the costs imposed by the new law. For example, the NZ law requiring pictorial health warnings on tobacco packaging did not compensate industry for printing costs or lost sales. Furthermore, we assumed no additional costs from the existing routine evaluation efforts by the NZ Government (nutrition surveys and food surveys) and negligible enforcement and legal costs associated with non-compliance (owing to the relatively low levels of corruption in the NZ setting and the high compliance with laws e.g., the law banning smoking in bars and restaurants [69]).

Salt substitution at 25 %

As per the row above, i.e., the cost of a new law.

Tight limits on sodium in bread (280 mg/100 g)

The cost is just that of the cost of a new law for NZ (see above). As per the arguments above, there was no consideration of reformulation costs and package labelling costs. The technology exists to manufacture lower sodium bread as per examples already present on the NZ market e.g., 186 mg/100 g for one multigrain bread [30].

Modest limits on sodium in bread (400 mg/100 g)

As per the row above.