Do purchases of price promoted and generic branded foods and beverages vary according to food category and income level? Evidence from a consumer research panel.

Price is a key determinant of food choice, particularly for low-income households who may be more sensitive to price-lowering strategies such as price promotions and generic/retailer-owned brands. Price-lowering strategies may therefore represent important policy targets to improve population nutrition and reduce inequities. This study aimed to describe household purchasing patterns of price promoted and generic branded foods and beverages in New Zealand (2016-2017). One year of grocery purchase data from a national consumer research panel in New Zealand (n = 1778 households) were analysed. Purchases were classified by processing level and food type. Linear mixed models were fitted to estimate the mean proportion of annual household purchases (unique items and volumes (kg/L)) that were price promoted or generic branded (overall and by food category), and to assess whether purchasing patterns were modified by income level. On average, price promoted products constituted 50% (95%CIs; 49,51) of all unique annual household grocery items purchased. Fifty-nine percent (95%CIs; 58,60) of processed, 55% (95%CIs; 54,56) of ultra-processed, 45% (95%CIs; 44,46) of unprocessed and 45% (95%CIs; 44,46) of ingredient purchases were price promoted. By volume, the proportion of purchases that were price promoted was highest for meat (65%[95%CIs; 64,66]), sugar-sweetened beverages (64%[95%CIs; 62,65]), dairy foods (64%[95%CIs; 63,66]), confectionary (64%[95%CIs; 63,66]), snack foods (63%[95%CIs; 61,64]), oils (61%[95%CIs; 60,62]) and non-sugar-sweetened beverages (60%[95%CIs; 58,62]), and lowest for dairy beverages (30%[95%CIs; 28,31]), sugar/honey (33%[95%CIs; 32,35]) and sauces/spreads (39%[95%CIs; 37,40]). On average, generic brands constituted 10% (95%CIs; 9,10) of all household purchases. Overall, a significantly greater proportion of purchases made by low and middle-income households were price promoted and generic branded compared to high-income households (p < 0.001 for both), a pattern generally observed across food categories. This study supports recent calls to address unhealthy food and beverage price promotions in comprehensive policy strategies aiming to improve population diets and weight.