Breast milk isn't just for babies at the Mothers' Milk Bank in San Jose, which quietly offers it to adults with cancer and other serious illnesses to ease their symptoms.

The milk bank is one of just six in the United States. It distributes donated breast milk primarily to premature and low-birth-weight babies. However, it also will provide breast milk to adults with a doctor's prescription.

Adult use of breast milk is rare, according to Pauline Sakamoto of the milk bank in San Jose, which has served 28 adult patients in the past four years. Adults with cancer, digestive disorders and immune disorders may drink several ounces of milk daily or weekly to ease the ravages of chemotherapy, bolster their immune systems and improve their digestion, she said.

No national figures exist for adult use of breast milk, but an informal survey of the nation's milk banks suggest that they currently serve dozens of adult patients.

Breast milk's benefits for babies have been well documented, with research showing that it helps fight infection, improves immune system function, increases intelligence and combats obesity in later life.

But can it help sick grown-ups? No one knows because so little research has been done.

In 1995 Swedish researchers isolated a protein in mothers' milk that seemed to kill cancer cells in a test tube. And they are still working on developing a drug that takes advantage of that protein. In 2004 the same research team found another compound that destroys many kinds of skin warts, raising expectations that the compound could help treat cervical cancer and other diseases caused by the human papilloma virus.

Still, most doctors are skeptical about the value of breast milk for adults, and mainstream medicine seems to consider it to be on the fringe.

Although Dr. Michelle Melisko, an oncologist at the University of California-San Francisco, acknowledges that mothers' milk probably won't hurt her patients, she worries about quality control -- some viral particles can be passed through breast milk -- and said she would advise them against using it.

A potential risk

``I'd say the same thing I say to all my patients who want to do alternative things: I don't know how it's tested,'' Melisko said. ``Patients are potentially exposing themselves to as many risks by taking milk from an unknown source than by taking herbs that come in a bag.''

Yet Margit Hamosh, professor emeritus at Georgetown University and an expert in the biochemistry of human milk, says breast milk contains compounds ``that might definitely help in people who have compromised immune systems in the same way they might help the newborn.''

Howard Cohen, a Palo Alto software consultant with a doctorate in theoretical physics, says he can live with the lack of medical evidence. Indeed, he's his own research study. Cohen believes that the twice-weekly smoothies he makes with breast milk and fruit have helped put his prostate cancer into remission and allowed him to avoid more invasive treatment, such as surgery.

``You give this stuff to newborn babies,'' Cohen said. ``It can't be toxic.''

After Cohen was diagnosed in 1999, his wife found an article about the Swedish research on breast milk and cancer cells. A friend who was lactating donated some milk, and Cohen soon found that his levels of prostate-specific antigen, a warning sign of cancerous cells, dropped back to normal. His doctor, a UC-San Francisco urologist, was skeptical but open to Cohen's self-treatment as long as his blood work looked fine. Cohen undergoes blood tests and other screenings religiously, and in the past 2 1/2 years, there have been no signs of cancer, he said. It's possible, of course, that without the breast milk, Cohen's prostate cancer might have grown so slowly that his health would not be compromised; that happens in many cases.

`It works'

Still, Cohen believes. After all, when he temporarily stopped the breast milk, his PSA levels went up. ``It works,'' he says simply.

Patty, an East Bay health educator who asked that her last name not be used, said breast milk seems to be helping her 15-year-old son, who this spring was diagnosed with Crohn's disease, a serious bowel disorder that can stunt growth and destroy the liver. Daily doses of breast milk mixed with chocolate syrup kept her son's symptoms under control, allowing him to gain weight and tolerate a regular diet, she said.

Although her son experienced a flare-up of symptoms that landed him in the hospital after five months on breast milk, Patty still gives him eight ounces a day, until their supplies are used up. Her son is now on anti-inflammatory drugs that control his disease. He can no longer tolerate chocolate syrup and must hold his nose to get the milk down, Patty said, but he's in remission. Because of the stigma surrounding adults drinking breast milk, her son wants to keep it a secret from his high school friends, she said.

``This is like liquid gold. We have this incredible untapped resource that we've only looked at for what it can give babies,'' Patty said. ``I'd love for more studies to be done on this. There's got to be something helpful going on.''