Dieters who ease their hunger by chewing all day on sugarless gum or candy can develop severe, sometimes dangerous diarrhea, according to a new medical report.

The hazard of "dietic food diarrhea" occurs in heavy users of gum and foods containing the sugar sorbitol or related sugars, according to Dr. Mario J. R. Ravry, a gastroenterologist who warned of the risk in this weeks Journal of the American Medical Association.

Sorbitol and its relatives, the hexitols, are naturally occurring sugars that are not absorbed during digestion. They have been used as dietetic sweeteners since 1929. While they are considered safe in moderate amounts, Ravry said, diarrhea from their overuse could lead to dehydration -- a serious risk for anyone with heart disease, diabetes or other medical problems.

Sales of sugarless gums and candies amount to $425 million a year, according to one industry estimate. A survey done this year by Life Savers Inc., one manufacturer of the products, found that half of those questioned (who were all between 13 and 49 years old) had used sugarless gum or candy in the preceding month.

The risk of diarrhea appears limited to those who consume more than about two ounces of sorbitol a day -- about as much as contained in 25 sticks of gum.

The patient described in Ravry's article was a 29-year-old man who each day chewed two packs of sugarless gum and ate two rolls of sugarless mints, two dietetic candy bars and two dietetic wafers.

Ravry said the man began using the products in order to stay on his diet, and within a few days developed watery diarrhea and cramps, with five or six bowel movements a day. He underwent extensive X-rays and tests, but no cause was found. Ravry said that what he questioned the man about his food intake, he immediately suspected the dietetic sweetner.

"It was almost an instantaneous diagnosis," he recalled. Sure enough, the diarrhea disappeared when the man stopped using the products, and reappeared when he tried using them again in large quantities.

Sorbitol and related sugars are used to sweeten "sugarless" gums, candy, jams and jellies, cookies, baking mixes and frozen dairy products. They are not an ingredient of diet soft drinks, which contain saccharin as a sweetener.

The sugars are dietetic because the calories they contain are not absorbed during digestion -- and this is also the reason they can cause diarrhea. Sorbitol and other hexitols pass through the intestines and draw extra fluid into the stool by a process called osmosis. Doctors have known for many years that diarrhea is a possible side effect, and sometimes even use the sugars to produce it deliberately, in order to clear the bowels before certain X-ray tests, or to treat liver and kidney failure.

Ravry said that what happened to his patient could happen to anyone who ingested similar amounts of dietetic foods. He added that the fluid loss caused by such severe diarrhea could produce angina or even a heart attack in someone with heart disease, and could contribute to a stoke or blood clot in someone with circulartory problems.

He said that diabetics, who sometimes rely on sorbitol-containing foods as sugar substitues, already risk getting diarrhea as a complication of diabetes. And for them, dehydration produced by diarrhea would be particularly dangerous.

Ravry said dietetic foods were fairly safe as long as they were not consumed in very large quantities. "Many diebetics and dieters do not go that route," he said. "They prefer to diet."

Sorbitol and its relatives have been considered the least controversial of the sugar substitutes. For the last six years the Food and Drug Administration has included them in its list of substances "generally regarded as safe," according to Dr. Corbin I. Miles of the agency's Bureau of foods.

Miles said the agency does require a warning of the substances' laxative effect to appear on foods that might be ingested in amounts exceeding about 2 ounces a day. But gums and candies do not fall in the category.

Spokesmen for several manufacturers of the dietetic products said they were aware of the risk of diarrhea, but, that it only occurred in people who abused dietetic food and gum.

"Twenty-six sticks of gum is an abnormal amount of gum for one person to chew in a day," said a spokesman for ht manufacturer of Trident gum, the Warner-Lambert Co.