The increasingly common "food allergies" or "food sensitivities" diagnosed by practitioners of a new and controversial medical speciality called clinical ecology appear overwhelmingly to be the result of the power of suggestion rather than true allergies, according to a report published today.

In recent years, "environmental illness," purportedly caused by multiple allergies to foods or synthetic chemicals, has become a popular explanation for a host of vague and difficult-to-treat problems, including headache, insomnia, palpitations, stuffy nose, depression, fatigue, intestinal gas, anger, learning disability, hyperactivity, bed wetting and memory loss.

Doctors calling themselves clinical ecologists or environmental medicine specialists frequently test for such allergies by injecting a small amount of a solution containing the suspected allergen under a patient's skin and waiting to see if the injection brings on the patient's symptoms. If it does, many clinical ecologists then prescribe a treatment involving regular injections of a somewhat larger dose of the allergen, to "neutralize" the allergy.

The procedure differs from conventional allergy skin-testing, in which a doctor makes small scratches on the skin, applies potential allergens and looks for a characteristic reaction that signals sensitivity.

The study did not address certain genuine food allergies or other forms of food intolerance that have long been recognized by medicine. These are considered relatively uncommon and usually cause a narrow range of symptoms such as indigestion or the sudden swelling of mucosal tissues. They are not diagnosed by the tests of "clinical ecologists."

Don L. Jewett, an orthopedic surgeon at the University of California at San Francisco and the study's principal author, said he undertook the research because he had been successfully treated, for a time, by a clinical ecologist and believed that the testing procedure had merit. The study was paid for by the Academy of Otolaryngic Allergy and the American Academy of Environmental Medicine, two organizations for clinical ecologists that together have about 2,500 members.

Jewett said that, when clinical ecologists test patients, the patients generally are told in advance what each injection contains. In the study, by contrast, the patients were not told. To eliminate the possible role of suggestion in provoking symptoms, each patient was given 12 injections in random order. Three injections contained the substance to which the patient was supposedly allergic and nine were "control" injections containing only an innocuous salt solution. After each injection, the patient was asked to report any symptoms that developed over a 10-minute period and then to guess whether the injection contained the allergen.

Neither the patients nor the technicians administering injections knew what was in the coded syringes. The patients were tested in their own doctors' offices, and solutions were prepared and administered by the same technicians who had tested them previously.

Patients were about as likely to guess that injections containing salt solution were "active" as they were to identify the allergen-containing injections. They correctly identified 27 percent of the "active" injections, and they mistakenly called 24 percent of the "control" injections "active." Patients were equally likely to report symptoms after "active" injections or after salt-solution injections.

Among seven patients who were given a "neutralizing" injection to relieve their symptoms, the symptoms were equally likely to disappear whether they had been provoked by an "active" injection or by one that contained salt solution.

Jewett said he was surprised by the study's negative findings. "I believed it was going to be positive," he said. "I looked at it every way I could think of. It's just completely consistent with randomness. And that's the only thing it's consistent with."

He said that when he reported the results to the American Academy of Environmental Medicine, one of the groups that funded the study, "they were mad at me. The first thing they said was, 'Who authorized this study?' "

Sherry Rogers, a New York environmental medicine specialist on the organization's board, said the study proved nothing because provocation-neutralization testing did not work in all patients. "It does work, but it's not in everybody," she said. "When it does, it's dynamite."

She said she had successfully treated patients with ulcerative colitis, rheumatoid arthritis and other serious disorders, and that "neutralizing" injections had cleared her own facial eczema.

Jewett said that clinical ecologists are usually enthusiastic, sympathetic doctors drawn from a range of specialties, and that most are not trained as allergists. "They honestly believe they are right. They are not charlatans," he said.

Both the American College of Physicians and the American Academy of Allergy and Immunology have issued position papers calling the practices of clinical ecologists unproven and controversial. Jewett said he believed that patients who consult clinical ecologists suffer from real, frequent symptoms, and that when such symptoms occur during a testing session, they tend to associate them with the injections.

He said one specialist in the Sacramento area treats many of his patients with injections of the "north wind" (the air is bubbled through water that is then injected as the neutralizer) because they complain that they feel worse when the wind blows from that direction.

"My basic underlying theory is that these patients are very stressed," he said. "Almost all have very unsatisfactory lives. Many feel helpless. Ultimately, they get trained, Pavlovian style, into reacting to the needle."