Starting today, customers at 90 area Giant Food stores will be greeted by a display of posters and pamphlets giving cautious counsel on foods that may - and may not - contribute to good health.

The year-long pilot program, called "Foods for Health," is a cooperative venture between Giant and the National Heart, Lung and Blood Institute. It marks the first time the federal government and private industry have collaborated to advise the public about nutrition.

The possible hazards of high salt and sugar consumption will be among many issues addressed by the program over the coming months, but the initial emphasis is on cholesterol and heart disease.

"Treat Yourself to LESS FAT," suggests a poster above the vegetable counter of a Rockville Giant outlet. "SEE HOW! Pick up an EATERS's ALMANAC."

"There is very, very clear evidence that the higher the level of cholesterol is, the greater the risk of heart attack," said Dr. Robert Levy, director of the Heart, Lung and Blood Institute would like consumers to make.

"We expect that we are going to get some changes," predicted Dr. Steven Zifferblatt, who helped develop the program. "It says 'you decide,' but it gives them a definite drift. We hope people will buy lower fat foods."

The program will feature colorful posters and shelf signs listing the fat, cholesterol and calorie content of about 50 different foods. A free "Eater's Almanac" will offer the "facts and fiction" about the realtionship between diet and disease.

The first issue of the Almanac exhorts the shopper to: "Look at what we know and don't know. Then you DECIDE whether to use some of these facts when you buy and prepare food for your family." iant's consumer adviser, Odonna Mathews, promises that future almanacs will provide recipes and other practical nutritional information.

The almanac will be changed every two weeks to feature 26 subjects, ranging from the merits of winter fruits and vegetables to the role of salt and sugar in heart disease.

The materials will be designed to be "competitive" with other advertising messages shoppers receive, Zifferblatt said. "We're doing advertising as professionally as anyone else. And we are at a place where people make their decisions."

Giant has no clear vision of the program's effect. Matthews conceded. "I feel quite strongly this is an experiment because I don't know the best way to communicate to the consumers'" she said. "There is so much conflicting information in the stores."

The program, which was announced at a press conference yesterday, will cost Giant $150,000, company officials said. It will be evaluated at the end of the year to see if people have changed their buying and eating habits. The Heart, Lung and blood Institute will compare data collected from Giant's Washington stores, where the program is in effect, with sales figures from the chain's Baltimore stores, where it is not in effect.

Zifferblatt said the institute "expects to see some changes," but Mathews was not quite so confident. "I don't know if it's enough time," he said.

If the program accomplishes its purpose, he indicated, the institute would like other supermarkets chains to follow suit.