In an item on mayonnaise (Health Plus, June 12), the American Heart Association's recommended daily intake of cholesterol for adults is 300 milligrams, not 500, as reported. (Published 6/26/90)

People used to think that a ham and cheese sandwich just didn't taste the same without a dollop of mayonnaise to jazz it up.

But now that Americans are more concerned with fitness and nutrition, mayonnaise -- a mainstay of many summer dishes -- has acquired a bad reputation. Not only do people think it is high in cholesterol, they worry that the dressing can cause food poisoning during warm weather. Neither is necessarily true, according to most nutrition experts. First, mayonnaise has only 5 or 10 milligrams of cholesterol per tablespoon. The American Heart Association recommends eating less than 500 mg of cholesterol a day, so the amount of cholesterol in mayonnaise is not that significant, said Karen Miller-Kovach, assistant director of nutrition at the Cleveland Clinic Foundation.

What gives mayonnaise a bad name is its high fat content -- and a diet high in fat has been linked to increased levels of cholesterol in the blood. Even cholesterol-free mayonnaise often has the same amount of fat -- 11 grams per tablespoon -- as regular mayonnaise. In fact, most of the calories in mayonnaise -- about 100 per tablespoon -- come from fat in the oil used to prepare the dressing.

For people searching for painless ways to cut calories, light mayonnaise, which has about 4 grams of fat and 40 calories per tablespoon, is a better choice, said Kovach. Manufacturers simply add more water to the commercial recipe of oil, food starch, eggs and vinegar to make light versions of mayonnaise.

In addition to the cholesterol myth, commercial mayonnaise is unfairly targeted as a source of food poisoning during warm months, according to the Food and Drug Administration. Because of the vinegar, mayonnaise alone often has a high enough acidity level to prevent bacteria from growing.

"The problem with mayonnaise comes when it is mixed with other foods like tuna or potatoes," said Charles Otto, assistant director of the Retail Food Protection Branch at the FDA. The acid level changes, creating an environment for bacteria to grow.

To prevent exposure to harmful bacteria, food safety experts recommend keeping mayonnaise refrigerated, particularly after the jar has been opened. When picnicking, salads prepared with mayonnaise should not be left out for more than two hours.

Homemade mayonnaise can be more hazardous than commercial brands because it is prepared with raw eggs. In recent years, uncooked eggs have been implicated as a cause of salmonella poisoning, an intestinal infection that is sometimes fatal. Symptoms include fever, diarrhea and vomiting.

Salmonella poisoning can be very dangerous to the elderly and people with suppressed immune systems. "When eating anything prepared with raw eggs, we are taking more of a risk than we use to," said the FDA's Otto.