Once a day, Matthew Hudson takes a square of chocolate mixed with green-tea extract and lets it dissolve in his mouth. Hudson, who has leukemia, is skeptical of natural therapies. But he has been taking the concoction for more than three years, ever since his doctor at the Mayo Clinic suggested it. “My disease has not progressed since I’ve been taking it,” said Hudson, a retired lawyer and investor from northern Virginia. “What does that mean? I don’t know. It means I’m not going to stop taking it.”A study by Mayo Clinic researchers last week provided more reason for hope. They found that high doses of green-tea extract can have a positive effect on Hudson’s type of cancer, chronic lymphocytic leukemia (CLL). The saga of Daniel Hauser, the 13-year-old Minnesota boy with Hodgkin’s lymphoma, has sparked public debate over the value of natural medicine, especially in cancer treatment. In labs at Mayo and elsewhere, scientists are putting those same questions to the test, training their microscopes on everything from shark cartilage to mistletoe and finding some surprising answers.

At last count, the National Institutes of Health’s center for complementary medicine had sponsored 47 cancer-related studies — on macrobiotic diets, soy, Reiki-energy healing, yoga, flaxseed, self-hypnosis, fish oil, massage, acupuncture and more. So far, most have focused on how alternative therapies can help ease the pain or side effects of cancer treatment, says Mary Jo Kreitzer, director of the University of Minnesota’s Center for Spirituality and Healing. Studies that have looked for cancer-fighting properties have been disappointing, she said. “There have just not been good vigorous studies that have found these natural remedies to cure cancer,” said Kreitzer, who is both a scientist and a supporter of complementary medicine. The green-tea study shows the promise, she said, as well as the difficulties in trying to tap nature’s curing powers.