Asking schoolchildren to scoff chocolate bars in return for sports equipment is a marketing ploy Cadbury may wish to forget.

Its Get Active! campaign, asking customers to redeem wrappers in exchange for sports kit for local schools, was panned, as it emerged that a school's pupils would need to eat 5,440 chocolate bars to receive volleyball posts and a net.

Yet the number of brands using cause-related marketing - which links purchases of a product with fundraising for a worthwhile cause - is growing all the time. UK companies donated £813m in pre-tax profit through CRM initiatives in 2005 [according to Business in the Community]. Businesses believe the benefits of being seen as socially aware, accountable and responsible are a key metric to rival the bottom line. But does CRM work? And if so, when and how?

A new report shows UK consumers feel increasingly indifferent about partnerships between brands and ethical or charitable causes.

The exclusive research for The Grocer by marketing company Richmond Towers reveals, only one in five respondents could name a food or drink brand that supports a good cause or charity programme (fig 3). And more than 60% of the 1,228 surveyed said they had never decided to buy a food or drink brand because it supported a worthy cause (fig 5).

However, surely the most revealing conclusion for the food and drink industry to draw is the fact that CRM campaigns that failed tended to focus on health, nutrition and, in particular, obesity.

That's because, in a list of 10 issues, including animal welfare, British poverty, education, and the environment, only 3% of people said nutrition and obesity concerned them the most.

With widespread media coverage, and millions spent on the obesity epidemic, how can this cause be such a turn-off? Obesity is an extremely personal subject, says Barbara Harpham, director of Heart Research UK. "It's hard to get people to discuss issues such as obesity and heart disease. No one wants to say 'you're fat; you need to change'. It's dangerous territory."

CRM campaigns are nothing new. It's been a quarter of a century since American Express officially trademarked the term "cause-related marketing" on the heels of its extremely successful Statue of Liberty Restoration Fund campaign, which raised Amex card use 27% and new applications 45%.

And it was way back in 1993 that Tesco debuted its successful Computers for Schools campaign.

But CRM is a tactic now used by nearly all major companies. Asda, Avon, Blockbuster, Boots, BA, Cadbury, Ford, Gap, Innocent, McDonald's, Morgan Stanley, Sainsbury's, Tesco, even British American Tobacco have added CRM activity to their marketing.

That's because, if you pick the right cause, CRM can be highly effective. And it's ethical and environmental issues that appear to get the most positive reaction from consumers in this sector.

There are numerous examples of success. Volvic received a number of plaudits for the successful launch of its '1L = 10L For Africa' campaign across Europe and Japan three years ago. The campaign, supported by World Vision, arrives in the UK in February and is billed as the UK's first ethical initiative by a major water brand.

The founder of Belu Water might disagree. His bottled water company donates its entire profits to global clean water projects, and he won The Independent's Social Entrepreneur of the Year award this month.

In the meantime, Innocent Drinks has recorded year-on-year sales growth of 60.6% after it joined the Carbon Trust's eco-labelling scheme and promised to have all its bottles made from recycled plastics by the end of January this year.

These successes demonstrate that the ties between product and cause should be obvious. "The most successful campaigns are long-term, driven by relevance and real understanding between the brand and the charity or cause partner, which delivers great results for everyone involved," says Catherine Sermon, community impact director, Business in the Community.

Even McDonald's, a perennial target for nutrition and health organisations, has been able to use CRM effectively. When the 2002 movie Super Size Me grossed £15m worldwide, memorably and graphically linking McDonald's to the global obesity epidemic, it could have put health and nutrition at the top of its CRM agenda.

Instead, with its World Children's Day partnership with Unicef, it has donated one day's global sales every year to children's charities around the world, raising £35m. By doing so, the burger chain has buffered its reputation against lobby groups and countered some of the negative publicity effectively. (On the other hand, when it emerged that it was sponsoring school report cards in Florida, earlier this month, it was pilloried by the media, and forced to pull them.)

Of course, there's always a danger that the public becomes cynical of CRM. The study reveals the impasse for retailers and food and drink manufacturers. On the one hand they must contend with consumers' belief that, whatever the issue, they are more concerned about making money and less about resolving problems of society. Only 9% of the public believes the charity benefits the most from CRM compared with nearly 60% of people who believe the brand benefits the most (fig 2).

On the other hand, consumers have come to expect demonstrations of CSR from the private sector. Companies must focus on the manner in which they go about business, with their environmental impact, employee morale, advertising, and role of the brand in the community all under the spotlight.

Experts, more pragmatically, say CRM is necessary just to elevate a brand above rivals who don't engage in CRM. "CRM may end up only affecting the companies that don't do it. It won't necessarily be of benefit to those who do because it will just bring them up to par with everyone else," says Harpham.

Fortunately for the food and drink industry, it is strategically well-positioned to benefit from such accountability. And the survey found nearly one in four people perceived the industry to be the most responsible sector in the UK market.

Hugh Burkitt, chief executive of the Marketing Society, believes the intimate relationship between the food industry and consumers is hugely conducive to CRM. "Food and drink is more frequently purchased by consumers than anything else.

"The opportunity to run ­successful CRM campaigns is therefore especially available to grocery retailers and food and drink brands," he says.

The dichotomy for the industry is that while the majority of those surveyed said nutrition and obesity would be the most appropriate cause for food and drink companies to embrace, it is low down the list of causes that the public appears to value.

Even relatively healthy and wholesome brands can suffer a backlash. In 2000, Nestlé was fined £7,500 for unsubstantiated health claims it made during a CRM campaign with the British Heart Foundation. Magistrate Philip Browning ruled that the claims, supported by the BHF, created an "irresistible inference that eating Shredded Wheat will reduce the risk of coronary heart disease." Both the BHF and Nestlé were censured for the ads, which appeared on 10 million cereal boxes and breached advertising regulations, and Nestlé had to deal with additional criticism for implicating such a well-respected organisation.

Kath Dalmeny, deputy co-ordinator of Sustain, worked for The Food Commission at the time of the Nestlé/BHF case and headed up a subsequent investigation into the furore. Concern still exists that health charities should maintain their credibility and independence, she says. "A big part of their role is to give the public advice about healthy eating, yet the products they help to promote are sometimes less than healthy," she says. "Credibility and independence are precisely the qualities that for-profit organisations want to partner with. But by these partnerships, the charity's independence and integrity can be compromised, which can reduce confidence in their health advice, which is to everyone's detriment."

Some CRM campaigns involving health and obesity are working, however. Sainsbury's Active Kids campaign, which shares an identical voucher collection scheme to Cadbury Get Active!, has raised over £52m-worth of sports and cooking equipment for schools and youth groups, and an international jury of retailing experts voted it Marketing Campaign of the Year in the 2006 World Retail Awards.

But the supermarkets are unquestionably in a better position than food and drink brands because of the diversity of products they sell, says Steve Mellor, consultant at Catalyst marketing consultancy.

"Whereas unfortunately Cadbury only has a chocolate portfolio to its name, Sainsbury's CRM campaign has the benefit of a wider roster of healthier and more wholesome food and drink products for consumers to purchase."

Sometimes you have to question whether CRM is really worth it. Only 1.3% of respondents could independently name any Innocent CRM campaigns despite its award-winning Supergran campaign, which raised £115,000 for Age Concern in 2006. Fewer still, 0.09% of respondents, could name Tesco without prompting as an example of a brand with a cause attached.

But with 24 to 34-year-olds 60% more likely than other age groups to have actually bought a CRM product in the last month, it bodes well for the future, as a generation of more socially and ethically minded consumers comes of age.Dos and Dont's

DO plan your cause-related marketing (CRM) for an issue which is relevant to your company

DON'T bank on health and nutrition causes: ethical and green issues have more appeal

DO remember CRM requires an open and honest partnership with the charity

DON'T compromise on the product's quality, although you can up its price slightly

DO ensure your CRM is part of a wider company commitment to corporate social responsibility

DON'T make the CRM too complex: a simple campaign is easier to participate in

DO target your campaign to 16 to 34-year-olds: they respond well to CRM and are the future