Boycotts by ethical shoppers cost big brands at least £2.6bn a year, claims the Co-operative Bank.
Fairtrade products are becoming increasingly popular
Its Ethical Purchasing Index found that in 2002 ethical consumption in the UK was worth £19.86bn.
More than half of UK shoppers claim to have deliberately avoided at least one product because of their principles.
Ethical banking, energy, and food products are all growth areas, but the total market share of ethical goods and services is still less than 2%.
The Co-op estimates that £6.9bn was spent on ethical goods and services, including Fairtrade food products, while £7.4bn went to ethical financial services.
In addition around £5.6bn was spent in line with consumers' principles through shopping locally, boycotting big brands, recycling and using public transport.
Simon Williams, director of corporate affairs at The Co-operative Bank, said: "The full extent of ethical consumerism will always be difficult to gauge, given that it is about the motivation behind a particular purchase as much as
the product or service itself.
"For instance, many people shop locally for convenience but for others the overriding consideration is to buy from local stores in order to support their community."
The Co-operative research found sales of energy efficient household appliances now have a 41% market share, and 40% of eggs sold are free range.
William Sankey, author of The Good Shoping Guide, said: "It is great that ethical purchases generally are growing.
"The effect of the boycotts - £2.6bn - might not seem a great deal at this stage... but we believe big companies listen to this sort of thing."
But while 80% oppose testing cosmetics on animals, sales of cosmetics that comply with the Humane Cosmetics Standard
have yet to achieve a 2% market share.