Impact of a targeted direct marketing price promotion intervention (Buywell) on food-purchasing behaviour by low income consumers: a randomised controlled trial

Background Price promotions are a promising intervention for encouraging healthier food purchasing. We aimed to assess the impact of a targeted direct marketing price promotion combined with healthy eating advice and recipe suggestions on the purchase of selected healthier foods by low income consumers. Methods We conducted a randomised controlled trial (n = 53 367) of a direct marketing price promotion (Buywell) combined with healthy eating advice and recipe suggestions for low income consumers identified as ‘less healthy’ shoppers. Impact was assessed using electronic point of sale data for UK low income shoppers before, during and after the promotion. Results The proportion of customers buying promoted products in the intervention month increased by between 1.4% and 2.8% for four of the five products. There was significantly higher uptake in the promotion month (P < 0.001) for the intervention group than would have been expected on the basis of average uptake in the other months. When product switching was examined for semi-skimmed/skimmed milk, a modest increase (1%) was found in the intervention month of customers switching from full-fat to low-fat milk. This represented 8% of customers who previously bought only full-fat milk. The effects were generally not sustained after the promotion period. Conclusions Short-term direct marketing price promotions combined with healthy eating advice and recipe suggestions targeted at low income consumers are feasible and can have a modest impact on short-term food-purchasing behaviour, although further approaches are needed to help sustain these changes.