VATICAN CITY -- Patients who are in a persistent vegetative state, even for years, must be given nutrition and hydration as long as their bodies can absorb the nourishment, Pope John Paul II said.

"The administration of water and food, even when delivered using artificial means, always represents a natural method of preserving life and not a medical act," the pope told an international group of physicians and ethicists.

The pope met the group March 20 at the end of a four-day meeting on the ethical decisions surrounding life-sustaining treatments for patients in a persistent vegetative state.

The conference, sponsored by the Pontifical Academy for Life and the World Federation of Catholic Medical Associations, brought together dozens of speakers with differing points of view, especially regarding the moment when providing artificial nutrition and hydration goes beyond an act of protecting human life and becomes a burdensome fight against death and the hope for eternal life.

Pope John Paul told the group that, while "vegetative state" has been accepted as a medical description of the clinical condition of patients who give no sign of consciousness or awareness of their environment, too many people think "vegetative" also describes the patients themselves, as if they were no longer human.

"I feel an obligation to reaffirm vigorously that the intrinsic value and the personal dignity of every human being does not change no matter what the concrete situation of his life," the pope said.

A human being "never becomes a 'vegetable' or an 'animal,'" he said.

"Even our brothers and sisters who are in the clinical condition of the 'vegetative state' maintain their human dignity in its entirety," he said. "The loving gaze of God the Father continues to watch over them, recognizing them as his children who are particularly in need of assistance."

Pope John Paul said that as long as the patient is not dying artificial nutrition and hydration must be considered "ordinary and proportionate and, as such, morally obligatory to the degree that -- and as long as -- they reach their aim, which consists in providing nourishment to the patient and easing suffering."

The pope said an evaluation of the monetary costs of continuing care cannot outweigh the value of protecting human life.

Pope John Paul also urged doctors and parishes to do more to help the families of patients in a persistent vegetative state.

"They cannot be left alone with their heavy human, psychological and economic burden," he said.

Dr. Salvino Leone, a moral theology professor who works with the Hospitaller Order of St. John of God in Rome, said there is "a profound ethical and conceptual" distinction between causing death and letting someone die.

One must never hasten a patient's death, he told the conference March 20, and one always must provide pain relief, nutrition and hydration and take precautions so that bedsores and infections do not develop.

But a Christian, Leone said, also must recognize that "letting die is a service to the gift of God, the humble consciousness of being a creature in the face of divine will and the acknowledgment of his absolute lordship over human destiny. In a single word: It is a true act of faith."

Determining the exact moment when it becomes ethical to let someone die is difficult to determine, speakers at the conference said, and some argued that there even are instances when the artificial provision of nutrition and hydration is so burdensome to the patient and his or her family that it is not obligatory.

Dr. Gianluigi Gigli, president of the federation of medical associations, said the different positions presented at the conference reflected the complexity of the issues involved and the continuing search by Catholic ethicists and physicians to make decisions informed by the best medical opinions and the highest moral standards.

Ann Verlinde, president of the International Committee of Catholic Nurses, said that because nurses spend so much time with patients and their families their opinions should be given greater weight on hospital ethics boards and in discussions with individual families about continuing or withdrawing certain types of care.

In many situations, she said, "nurses find it easier than doctors to say, 'It is finished; let them go. We will be with them, caring for them as they die.'"

Msgr. Kevin T. McMahon of St. Charles Borromeo Seminary in Philadelphia said that with patients in a persistent vegetative state artificially delivered nutrition and hydration are simply "the medically assisted supply of food and drink."

He said people should keep in mind that, while a return to consciousness is "highly improbable" after one year in a vegetative state, withholding nutrition and hydration always results in death.

Dr. Eugene F. Diamond, director of The Linacre Institute of the Catholic Medical Association, based in Boston, said that while polls show most people would not want "life-sustaining" treatment if they had no chance of recovering consciousness he thought the responses would be different "if people were asked if they wanted to starve to death."

"No one is arguing to use all means, at all costs, for all persons in all circumstances, particularly those who are imminently dying and unable to benefit from the treatment," he said.

But with patients who are not dying, Diamond said, "our choice is really between caring for such persons or abandoning them."

In a presentation written with Ronald P. Hamel of the Catholic Health Association of the United States, Dr. John Collins Harvey of the Georgetown University Center for Clinical Bioethics in Washington offered concrete examples of cases in which artificial nutrition and hydration were necessary and useful and when they became overly burdensome.

He told of a woman in a persistent vegetative state for four years whose Catholic husband and six children struggled with decisions regarding her care, particularly because of aspiration pneumonia and lung damage caused by regurgitation.

"They questioned whether continued biological life was the highest good for the human person and whether maintaining biological life was always morally obligatory," he said.

Human life is sacred, he said, but the duty to prolong life "is not absolutely binding under all circumstances, because we know that our ultimate end lies in eternal life with God."

Msgr. Marco Frisina, director of the Diocese of Rome's liturgy office, told the doctors March 17 that when medical treatment is useless the focus must turn toward helping the patient die a "good death" -- not in the way proponents of euthanasia mean, but in the sense of dying with the sure hope of eternal life.