[London] U.K. retailers, food marketers and a government watchdog are locked in a battle over two rival food-labeling schemes. They agree that voluntary food labeling displayed prominently on the front of the package is an important weapon in the fight against obesity-and is good for corporate reputations-but that's about all they agree on.

In one corner is the Food and Drink Federation, representing most of the big food marketers, including Unilever, Coca-Cola, Nestle, Kellogg, Masterfoods, Danone, Cadbury Schweppes, PepsiCo and the U.K.'s biggest retailer, Tesco. They support the Guideline Daily Amount system of food labeling. The revamped GDA system shows shoppers the amounts of sugars, fats, calories, saturates and salt in a food item and the percentages of an adult's recommended daily consumption they represent.

In the other corner is the "traffic light" system devised by the government's Food Standards Agency, which is supported by major retailers including Sainsbury's, Waitrose, Asda and Marks & Spencer. The simple system uses red, amber and green signs to show at a glance if a food contains high, medium or low amounts of salt, fat, saturates and sugar.

The battle stepped up last week with an $8 million print and TV campaign for the GDA system using the tagline "Know what's going inside you" to present the guidelines as accessible and informative.

Rival ads for traffic-light labeling from the FSA break later this month. An existing campaign warning against too much salt has already been modified to include traffic-light labeling and advises, "Always check the label. Be in the know. High. Medium. Low."

Critics of the GDA system say its supporters are backing a complex and confusing scheme because they fear scaring away shoppers by putting big red lights on their food products.

can't do the math

"The food industry will be aware that their new labels will be useless to almost half of adults and most children, who simply lack the complex mathematical skills to interpret them," said Richard Watts, coordinator of the Children's Food Campaign. "The industry's system was designed only to give the appearance of action but at the same time avoid using the red labels that might actually discourage people from eating junk food."

His group's research found that 47% of adults lack the numerical skills to understand the percentages used in the GDA system. The FSA agrees. According to its research, 62% of people misunderstood the GDA labels, while only 21% misunderstood the traffic-light labels.

The traffic-light system is accused of oversimplifying choices and misleading consumers. Olive oil, for example, gets a red light even though it is generally considered to be healthier to cook with than butter.

A Tesco spokesperson defended the supermarket's position in the GDA camp: "Our nutritional signposts are easy to understand, and by giving the actual data rather than just a color, customers are able to make informed decisions. ... Our sales data show that where our labels have been applied, customers are already using them to move toward products lower in salt and fat."

According to Tesco, in eight weeks, sales of its Healthy Living egg-and-cress sandwich rose 97%, while standard egg-and-cress sales fell 30%.

Both labeling systems seem to affect sales. A tracking study of the traffic-light system by retailer Co-Op showed a 10% increase in sales of products signposted as low in salt, while those flagged as high in salt saw sales fell by 5%.

McCain Foods has just announced its decision to use both the GDA system and the traffic-light symbols.