Ulcers, hemmorhoids, upset stomachs and jumpy intestinal tracts are all digestive diseases, and all are often the subject of humor or ridicule.

But a federal commission said yesterday that these and other digestive tract illnesses are often grimly serious, and that refusal to discuss them adds to neglect of their causes and cures.

Such illnesses -- along with cancer of the colon, cirrhosis of the liver, hepatitis and gallstones -- are "tragically" underresearched, undertreated, and, to a large extent, ignored by the federal government, said the 26-member National Commission on Digestive Diseases created by Congress in 1976.

Yet these diseases, when looked at as a group, are "the leading cause of hospitalization," said Dr. Eugene Jacobson, the commission's chairman.

All digestive diseases cause 200,000 deaths a year, the commission report said.

Digestive illnesses account for 15 percent of all hospital stays. They cost the country $17 billion yearly in medical care, and another $35 billion in lost work and wages, the commission estimated.

However, federal funding for research into causes of and better treatment for digestive diseases totals less than $100 million, said Dr. Jacobson, associate dean of the University of Cincinnati College of Medicine.

"The number of people doing research is actually declining," said Dr. Paul Sherlock of Memorial Sloan Kettering Cancer Center of New York. "We're not attracting young people, and people already in the field are moving to other areas where funding is better."

At the same time, there are "vast areas of ignorance" about digestive diseases, the commission concluded.

The commission urged Congress to appropriate an additional $56 million in the coming fiscal year for study of digestive diseases. It asked Congress or involved agencies to establish a National Digestive Diseases Advisory Board and a new digestive diseases division at the National Institutes of Health.

Rep. Tim Lee Carter (R-Ky.), a physician and coauthor of the 1976 law creating the commission, introduced a bill yesterday to provide nearly $2 million to fund more training for health professionals, and establish the advisory board the commission sought.

"Given the current problems in the Congress," Dr. Jacobson conceded, "it may be a problem" to get a new $56 million."

"These are very common illnesses," said one commission member. "Maybe they're so common that people forget they can be serious.

"But President Eisenhower had regional ileitis, inflammation of the small intestine, and President Johnson had diverticulitis, an infection and inflammation of pouches in the large intestine. Both men had to have surgery. Fortunately, their operations were successful. But a good many people die of conditions like these."