An institute here has become the center of a controversy between the orthodox medical establishment and a man practicing a revolutionary method for treating cardiovascular disease and related illnesses such as diabetes.

It is housed in an innocuous looking white stucco motel facing the pacific Ocean, but the motel's residents are not ordinary guests. They are patients at Nathan Pritikin's Longevity Research Institute (LRI), people who have hypertension, angina (chest pains), atherosclerosis (clogged arteries), diabetes and all of their debilitating symptoms to various degrees shortness of breath, inability to walk more than a few feet, etc.

Through exercise and a highly restrictive diet, says Pritikin, who is not a physician but has five doctors on his staff, the patients are able to return to near-normal functions. When the program began in January of last year, Pritikin was also claiming a reversal of certain diseases and it is this claim more than improved functioning of the patients that has created the controversy.

In fact, the director of the National Institutes of Health Heart and Lung Institute, Dr. Robert Levy, agrees that the diet and exercise program would have beneficial results. But he said: "There is no evidence that in 30 days you can reverse atherosclerosis." Last fall Levy sent a team of investigators to Santa Barbara to study the institute's methods and results. He said, "We could find no evidence that they could substantiate their claims.

"You prove something by controlled scientific studies. We would hope we could do that some day. I consider it inappropriate to put those anecdotal claims in the press and the lay press at that, not the scientific press."

The most spectacular of what Levy calls anecdotal material concerns an 87-year-old woman, who according to a recent magazine article, "couldn't walk 100 feet without suffering crippling pains in her legs, and her circulation was so poor that she almost always wore gloves. Congestive heart failure, high blood pressure, angina, arthritis and heart disease seemed to have taken their toll."

That was in 1969. But in 1975 Eula Weaver was competing in the Senior Olympics in Irvine, Calif. In addition she had given up all her medication.

Miracle? "It's no miracle when you go on this diet and exercise," Pritikin said during a recent interview at his Santa Barbara office.

The diet is 10 per cent fat, 10 per cent protein and 80 per cent complex carbohydrates (whole grains, fruits and vegetables) along with a slow but increasingly, strenuous exercise program of walking. That was Eula Weaver's "miracle." And it has become a cure for several hundred patients over the last 15 months.

Candidates for the 26 day program, which costs $2,750 plus about $1080 in medical tests, often bring their spouses to LRI and always bring their medications. The daily routine is quite simple. There are eight low-fat, low-protein, low-cholesterol meals that are totally free of sugar except for that which occurs naturally in fruits, and other simple carbohydrates. No salt is added and foods naturally high in salt are not permitted. Coffee, tea and all alcoholic beverages are forbidden.

Between the eight mini-meals the patients must walk. For those who cannot walk more than a few hundred feet without shortness of breath, the distances are small in the beginning. By the end of the month the patients are walking at least six miles a day. Jogging and tennis are not ruled out for the more physically fit.

The day is also taken up with various tests to check the blook levels for cholesterol, triglycerides, blood pressure, heart stress. There are lectures about the relationship between diet and degenerative disease and how to carry on the program once the patient has gone home.

The regimen is based on the theory that the degenerative diseases of the Western world are the result of the rich diet high in fat, especially animal fat, refined foods filled with sugar, smoking excessive drinking and a sedentary life. The theory is not at all revolutionary. The treatment and prevention recommended by both Pritikin and the orthodox cardiovasuclar specialists are really a matter of degree not kind.

The current normal American diet is 42 per cent fat, 12 per cent protein and 46 per cent carbohydrate, of which only 22 per cent is complex carbohydrated; the other 24 per cent is sugar in various forms.

Physicians such as Levy believe that Americans' eating and living habits must be changed to prevent heart attacks but the changes they recommend are far more moderate. For one thing Levy does not believe that many would be willing to stick with Pritikin's highly restrictive diet. Levy said, "To follow the diet for an extended period would require great motivation and drastic restrictions in use of usual food products that most Americans currently enjoy. It is unlikely that many persons would be willing and able to continue such dietary restrictions very long after leaving the supervised environment provided by Mr. Pritikin's staff." Pritikin claims "80 to 90 per cent conformity" by former patients.

One of the LRI advisory board members, British physician, Hugh Trowell, agrees that the diet may seem hard to take for an outsider. He and Dr. Denis Burkitt, a British authority on the relationship between dietary fiber and degenerative diseases, spent several days at LRI, mainly, according to Trowell, to satisfy themselves that LRI is legitimate. Burkitt, who is also an advisory board member, and Trowell "snooped around" because they decided "if there is some hanky panky, we'd go away." While they were there they had trouble adjusting to the diet. "You do run into the palatability question," Trowell said. "Denis had to go out and buy cookies." But he said, "I couldn't find anyone there who said he was hungry. That was a miracle and I was taught not to believe in miracles."

Pritikin, who is 61, doesn't think the diet is difficult to follow and said he and his family had been eating that way for years. He is an inventor with several patents that bring him as "independent living." He has been interested in the cause of heart attacks for 30 years.

"Diet," Pritikin said, "is a cultural habit. Everyone loves his own diet, but you can unlearn it. You need education and you need conviction."

Pritikin believes that conviction to follow the rigorous diet comes from a "guarantee you will have a pain-free existence. The pain makes it worth chaing your diet."

In addition to pain some of the patients who go to LRI are facing coronary bypass surgery. A few face amputation of a leg, because of a condition known as claudication in which the blood supply to the leg decreases because the arteries are clogged: gangrene often results.

According to Pritikin two of the three patients facing amputation have been saved from surgery because the LRI diet and exercise program has, if not unclogged the arteries, at least permitted a better flow of blood.He also claimed a number of the candidates for bypass surgery have been saved from it. When people are faced with that kind of surgery, Pritikin said, they are motivated to change their life styles.

Other less dramatic cases involve improvement in cholesterol and triglyceride levels, reduction in blood pressure, reduction in the blood sugar level of diabetics. Such improvement has meant a reduction, even complete elimination, in medication the patients were taking when they arrived.

Pritikin said he is "willing to guarantee that 90 per cent of drug-controlled hypertensives are drug-free after 30 days.

"Hypertensive drugs are not innocuous," he said, and "people should know alternatives."

Dr. Levy does not dispute these results because he said the LRI diet is a weight-reducing diet. "If people lose weight, and the diet is a weight-reducing diet, it's no surprise to see the blood levels go down. All of the things Pritikin is seeing have been seen before on a calorie-restricted diet.

"If Pritikin wants to claim people feel better and can walk further and lose weight in the 30 days I have no objection, but if he wants to claim he has reversed atherosclerosis or has a cure-all that can help of America, that's not true."

Pritikin does think he has a kind of cure-all for what ails Americans.

"Young Americans," he said, "have plenty to worry about. In our country everyone over 20 years old has somewhat closed arteries because of our diet. After a good American meal the blood looks like a can of tomato soup. It's a greasy mess."

Pritikin has nothing good to say about the Heart and Lung Institute at NIH or the American Diabetic Association. He contends their dietary recommendations do more tharm than good.

But he has backed off his claims for reversal of atherosclerosis: "We do not talk reversal, we talk about return to normal function. We have too few cases of (anatomical) reversal but tremendous functional reversal."

Not that anatomical reversal is out of the question, according to a study published in the Sept. 18, 1976, issue of The Lanoet, a respected British medical journal. According to the authors, there is still little evidence of reversal in man but there are "antherosclerotic conditions in animals, similar to the human condition, which do regress satisfactorily after dietary manipulation." The paper concludes: "Dietary change and weight-loss are unlikely to harm, and may well lead to regression of established antherosclerosis."