Cancer-fighting bacteria

The role of intestinal bacteria in health is not really new. Russian scientist and Nobel Prize winner Elie Metchnikoff believed that the aging process is controlled mainly by the presence of harmful substances in the intestines which interfere with the body's immune system.

Metchnikoff said that longevity can be achieved by taking lactobacilli, a bacteria found in yogurt which is regularly consumed by long-lived people in a certain Bulgarian region. His theory, however, was criticized by other scientists who said that the lactobacillus in yogurt, L. bulgaricus and Streptococcus thermophilus, are killed in the intestines and could not colonize there nor exert beneficial effects.

"The idea that the bacteria in live yogurt can flourish in the human intestines and that they are beneficial is very questionable,'" said Arnold Bender, vice president of the International Union of Food Science and Technology, in Health or Hoax?

Metchnikoff died at the age of 71 and his theory was dismissed. But Japanese scientists at the Yakult Institute have since come up with a special strain of lactobacillus which they claim can survive in the human intestine and check the growth of harmful substances there.
Lactobacilli casei-Shirota strain was originally isolated and cultivated by Dr. Minoru Shirota of Kyoto University Medical School in 1929. Shirota believed that by incorporating this helpful strain of intestinal bacteria in fermented milk products, he could improve the drink's nutritional value and, at the same time, prevent intestinal infections due to the effects of the beneficial bacteria. This idea led to the development of Yakult, a fermented milk drink popular in Japan and in other countries.

Shiroia's theory was recently confirmed by other Japanese researchers. Animal experiments carried out by the National Cancer Institute and the Yakult Institute in Japan showed that L. casei could enhance the body's immunity and fight cancer.
They arrived at this conclusion after studying the effects of L. casei on two groups of mice. Both groups were injected with a cancer-causing agent but those who received oral doses of L. casei had a lower incidence of cancer compared to those who didn't.
How does L. casei work against cancer? Scientists don't know for sure but they think that these beneficial bacteria stimulate the disease-fighting abilities of macrophages, white blood cells that devour bacteria and other foreign matter in the body.

Immediately after the macrophages recognize the cancer cell, they approach to mount an attack and at the same lime signal for help from the helper T-cells, killer T-cells, natural killer cells and B cells. Thus, the whole immune mechanism is mobilized to act on the cancer cell," said Dr. Yomotari Mitsuoka in "Microbes in the Intestine: Our Lifelong Partners."

Administration of bifidobacteria to children and infants has also been shown to control diarrhea caused mainly by the use of antibiotics. Children are given antibiotics to fight infections but this often results in diarrhea which can be fatal. Fortunately, this can be corrected with the administration of bifidobacteria.

Although Japanese researchers think that these and other diseases can be prevented by regularly taking fermented milk products containing lactobacilli and bifidobacteria which supposedly increase the amount of good bacteria in the intestine, other scientists remain skeptical of this simplistic approach pending the results of more extensive clinical trials.
"There is little agreement about what then becomes of the bacteria after they are eaten though it is clear that they live long enough to help digest the lactose they accompany into your mouth. Some promoters of yogurt-related products claim that they colonize the gut, crowd out undesirable bacteria and thereby digestion and alleviate intestinal disorders. Other promoters say no, only their special strain of X-ophilus survives and improves intestinal ecology and health. No one knows for sure; no one has ever proven that the expensive yogurt products people take to treat chronic digestive disorders, skin problems and allergies are not a complete waste of money," said Kurt Butler and Dr. Lynn Rayner of the John A. Bums School of Medicine, University of Hawaii, in "The Best Medicine."