The effects on saturated fat purchases of providing internet shoppers with purchase- specific dietary advice: a randomised trial.

Objectives: The supermarket industry now services many customers through online food shopping over the Internet. The Internet shopping process offers a novel opportunity for the modification of dietary patterns. The aim of this study was to evaluate the effects on consumers' purchases of saturated fat of a fully automated computerised system that provided real-time advice tailored to the consumers' specific purchases recommending foods lower in saturated fat.

Design: This study was a blinded, randomised controlled trial.

Setting: The study was conducted in Sydney, New South Wales, Australia.

Participants: The participants were consumers using a commercial online Internet shopping site between February and June 2004.

Interventions: Individuals assigned to intervention received fully automated advice that recommended specific switches from selected products higher in saturated fat to alternate similar products lower in saturated fat. Participants assigned to control received general non-specific advice about how to eat a diet lower in saturated fat.

Outcome measures: The outcome measure was the difference in saturated fat (grams per 100 g of food) in shopping baskets between the intervention and control groups.

Results: There were 497 randomised participants, mean age 40 y, each shopping for an average of about three people. The amount of saturated fat in the foods purchased by the intervention group was 0.66% lower (95% confidence interval 0.48-0.84, p < 0.001) than in the control group. The effects of the intervention were sustained over consecutive shopping episodes, and there was no difference in the average cost of the food bought by each group.

Conclusions: Fully automated, purchase-specific dietary advice offered to customers during Internet shopping can bring about changes in food purchasing habits that are likely to have significant public health implications. Because implementation is simple to initiate and maintain, this strategy would likely be highly cost-effective.