The Co-operative Group's focus on ethics, fairtrade and the environment has encouraged a growing number of younger shoppers to join its dividend scheme, according to the society.
The number of people under 40 joining the profit-sharing scheme has more than doubled from 16% to 40% since it was relaunched last September, it said.
They had been attracted by the society's belief in social responsibility and democracy, said group marketing director Patrick Allen.
"High-quality products and the ability to contribute to our community is a compelling reason to join the society," he added.
More men under 40 had also joined the scheme, a development attributed to the increase in the number of single households and men visiting convenience stores. Younger people were also attracted by the society's ongoing rebranding, which had made the Co-op more contemporary, he said. Expanding the scheme to encompass the group's bank, pharmacy and travel businesses as well as food had also given the scheme a wider appeal.
The scheme now has more than 2.5 million active members but this number is set to increase when more than one million members of United Co-op and 220,000 members of Midcounties Co-op join the scheme next year.
More than 50,000 members had already completed a questionnaire released in September to help the society set out its ethical priorities for its food business over the next three to five years, Allen added.