Guiding stars: The impact of nutrition rating systems on supermarket food sales

Can nutrition rating systems be used in supermarkets to encourage healthier spending habits? A new study by Cornell University researchers sought to answer that very question by tracking the purchasing records in a supermarket chain that uses the Guiding Stars System to rate the nutritional value of foods for sale.

The researchers, including Cornell Food and Brand Lab's David Just, PhD, and Brian Wansink PhD, author of Slim by Design (forthcoming), studied the sales records of over 150 Hannaford Supermarkets in the Northeastern United States between January 2005 and December 2007. They collected data from over 60,000 Guiding Star rated food items. The Guiding Stars System brands items with zero, one, two or three star rating (with three stars being the most nutritious). The amount of beneficial ingredients, such as vitamins and whole grains, are taken into account along with the amount of innutritious ingredients such as trans-fat or added sugars, both of which affect the nutritional rating of that item.

Researchers found that sales of less healthy foods – such as highly processed snack foods – fell by 8.31% when branded with a nutrition rating while the percentage of healthy food purchases rose by 1.39%. The authors also noticed that the use of the Guiding Stars system led to an overall decline in supermarket sales. However, this is mainly due to the reduced amount of purchased "junk food." According to lead author John Cawley, PhD, the decline in the sales of the less healthy foods was "perhaps the leading catalyst for the trend toward more nutritious food purchases." Previous studies may have not noticed this trend because they focused only on sales of foods with higher nutrition ratings.

Researchers concluded that nutrition rating systems, such as the Guiding Star system, may be worthwhile as they seem to lead consumers to purchase less "junk food" in favor of healthier options.