Some nutritionists and dietitians have for years complained about white bread, from government- mandated enriching processes to concern about white bread's low fiber content -- low dietary fiber is believed to increase the risk of colon cancer.

Yet the enriched white flour found in Wonder Bread "is not as much a disaster as it is sometimes portrayed," says Michael Jacobson, director of the Center for Science in the Public Interest. "It has about as much protein, starch and several vitamins and minerals as whole wheat flour, but it contains much lower levels of dietary fiber and perhaps a dozen minerals. It's okay in thiamin, iron."

What Wonder Bread lacks is "zinc, chromium, Vitamin B6 and several other B vitamins such as pantothenic acid and folacin," Jacobson says, as well as manganese and Vitamin E. Whole wheat bread, he says, has "twice as much more of those nutrients than white flour." Jacobson believes most people should eat whole-grain breads.

Paul Khan, Continental Baking vice-president for quality and food protection, says Wonder contains "traces of Vitamins A, B12, B6, biotin, folic acid, pantothenic acid and very small amounts of ascorbic acid." He says Jacobson's claim of a nutritional difference with whole wheat bread was true but not significant. "That's like one bite less of something," he says.

The Diet, Nutrition and Cancer Report, published in 1982 by the National Research Council and the National Academy of Sciences, emphasizes including fruits, vegetables and whole-grain cereal products in daily diets. Nevertheless, says Sushma Palmer, executive director of their food and nutrition board, the report "didn't say that you shouldn't eat white bread . . . That would be an unwise recommendation. You don't have to exclude white bread in order to get fiber in your daily iet."