Fair trade labels carry a promise—about how products or ingredients are sourced from developing countries—and according to a recent study, it can affect the value consumers put on a product.

In a study published September 2015 in Frontiers of Neuroscience, researchers at the University of Bonn in Germany had participants bid for a variety of food products. A picture of each product was shown twice, with and without a fair trade label, but never in sequence. Participants were willing to pay an average of 38.6 cents more for fair trade-labeled items.

This marked preference for fair trade products was shown again in a second experiment, where participants tasted and rated two chocolates—one they were told was a fair trade product and one that was not. Study participant ratings for expected taste intensity and experienced taste intensity and pleasantness were significantly higher for the alleged fair trade chocolate, though in reality the two chocolates they tried were identical.

The international Fairtrade certification mark, created by Fairtrade International in 2002, was recognizable to 57% of consumers across 24 countries, according to a 2011 study by GlobeScan. In the same study, 79% said the Fairtrade mark would “have a positive impact on their impression of the brand.” And more than three-quarters of those who are familiar with the mark are buying Fairtrade products regularly, according to Jorge Berges, senior business development manager for Fairtrade America.

The growth in consumer recognition and trust had a noticeable impact in 2014, when global sales of products carrying the Fairtrade mark grew 10% to hit $6.6 billion. The Fairtrade certification mark covers a wide variety of natural foods and products in the U.S., including chocolate bars, coffee, chewing gums, fruits and vegetables, honey, flowers and clothing. 

In the U.S., shoppers are likely also familiar with Fair Trade USA’s Fair Trade Certified label. It was recognizable by 55% of consumers in the U.S., according to a 2014 Natural Marketing Institute study. The nonprofit saw imports of Fair Trade Certified products increase by 26% in 2014, earning farm workers and small producers more than $5.5 million in the Produce and Floral category.

“More and more consumers—particularly Millenials—want to know how their food is being grown and who is growing it,” said Mary Jo Cook, chief impact officer at Fair Trade USA, in an official statement. “Brands are listening, and we are energized by the many new companies beginning their Fair Trade journey.”

Published in WholeFoods Magazine, 10/9/15 (updated 10/14/15)