NEWS: Putting Good Bacteria to Work

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September 14, 2004

Putting Good Bacteria to Work

By JANE E. BRODY

From a cellular perspective, you might think the human body was mostly

human. But you'd be wrong. It is actually mostly bacterial.

The typical adult body harbors about 100 trillion bacterial cells from at

least 500 species - 10 times the number of human cells. And that's not

counting viruses and fungi.

Most of these bacterial organisms are what medicine calls " friendly, " or at

least harmless. Friendly bacteria, or probiotics, serve a host of biological

functions important to the survival of the animal they populate. Some aid in

digestion, some compete with harmful bacteria and keep them in check, some

stimulate the immune system. And they may have other roles not yet known.

Researchers here and abroad are looking at probiotics as a promising answer

to the growing problem of antibiotic resistance and abuse. To date, studies

have indicated that ingested probiotics can play an important role in

preventing or controlling food and skin allergies in children, bacterial

vaginosis and premature labor in pregnant women, inflammatory bowel disease,

recurrent ear and bladder infections, dental caries, chronic diarrhea and

traveler's diarrhea. They may even help lower cholesterol in the blood and,

by degrading carcinogens, thwart the development of certain cancers.

Bacteria for Life

The health potential of probiotics has been known for about 100 years, but

their value has largely gone unrecognized by Western health professionals.

But interest in probiotics has exploded in the last several years in the

face of surging bacterial resistance to many potent drugs, consumers' demand

for natural remedies and accumulating evidence that some probiotic organisms

prevent or treat certain challenging medical conditions.

Probiotics, derived from the Greek phrase " for life, " are defined by the

World Health Organization as " live microorganisms which, when administered

in adequate amounts, confer a health benefit on the host. " There are three

crucial concepts in this definition - " live, " " microorganisms " and " health

benefits. " Contrary to advertisements for some products, foods themselves

are not probiotics, although some, like fermented milk, can be prepared to

contain enough beneficial bacteria to promote health.

Unfortunately, according to one prominent scientist in the field, Dr. Gregor

Reid of the University of Western Ontario, many foods and supplements now

being sold as probiotics are worthless. All too often, he said, the

organisms in them are present in too small a quantity to be beneficial. Or

the products contain species not yet shown in rigorous studies to benefit

health.

" Many so-called probiotic products have not been properly identified,

documented, manufactured under good manufacturing practices or proven

clinically, yet various companies make claims that lead consumers and care

givers to believe that they are using reliable products, " Dr. Reid and

colleagues wrote in Clinical Microbiology Reviews last October.

What Can They Do?

It has become increasingly apparent that the absence of bacteria in the

intestines is unhealthy. For example, laboratory animals raised to be

germ-free are often sickly, with seriously underdeveloped immune systems and

vulnerable intestinal tracts. Such a circumstance would render an infant

susceptible to allergies and life-threatening infections. One of the

best-documented benefits of probiotics has been preventing eczema in babies

with an inherited tendency to develop allergies.

For example, in a carefully designed study, researchers in Finland

administered the probiotic Lactobacillus GG to pregnant women and to their

babies who were considered at high risk for developing allergies for six

months after birth. By the time the children were 2, the probiotic cut the

incidence of eczema in half.

This organism " has proved safe at an early age and effective in treatment of

allergic inflammation and food allergy, " the researchers reported in the

journal Lancet. The mode of action is believed to involve the ability of

probiotics both to reduce the absorption of dietary allergens by enhancing

intestinal development and to degrade allergens in the babies' digestive

tracts.

The human digestive tract is sterile at birth but rapidly acquires

organisms. The first ones to become established dominate the system.

Nowadays, many infants are first colonized by organisms acquired in the

hospital, rather than the beneficial Lactobacilli and Bifidobacteria that

predominated when babies were born at home. Breast-feeding introduces

beneficial bacteria, which may account for the lower incidence of allergies

in breast-fed babies.

In another benefit to babies, Dr. Reid, a microbiologist, and his

obstetrical colleague Dr. Alan Bocking have reviewed the ability of

probiotics to prevent premature labor and delivery arising from bacterial

vaginosis. These infections, which often cause no symptoms or are

misdiagnosed as yeast infections, can invade the membranes around the fetus

and stimulate premature labor.

The Canadian researchers' studies of two strains of probiotic Lactobacilli

showed that when the organisms were taken by mouth, they tended to impede

the growth and establishment of various harmful bacteria known to cause

intestinal, urinary tract and genital infections that could invade the womb.

In an interview, Dr. Reid described other benefits to children of probiotic

bacteria that have been found in early studies by various researchers,

including fewer respiratory infections and dental caries, as well as fewer

episodes of and quicker recovery from diarrheal diseases.

For adults as well as children, some studies have suggested that regular

consumption of probiotics can reduce the chance of contracting travelers'

diarrhea and limit the formation of cholesterol, though not to the level of

statin drugs.

In Japan, many people regularly consume a probiotic drink called Yakult,

which has been shown to reduce the recurrence of bladder infections. Another

product, VSL-3, which contains eight different probiotic organisms and is

sold in Italy, may help keep Crohn's disease, a serious inflammatory bowel

disorder, in remission.

At the moment, however, the hype about probiotics and the explosion of

untested products in the United States have outstripped the science.

Products must resist stomach acid yet dissolve readily in the intestines.

They must also be protected from air and moisture to remain viable. If a

probiotic product is formed into chewable tablets, the application of heat

will destroy some organisms, so the manufacturer has to put enough in to

have enough left.

Many consumers rely on yogurt with active cultures as their source of

probiotics, but the organism most often used in these fermented milk

products, Lactobacillus acidophilus, is not the primary bacterium naturally

found in the gut, Dr. Reid said.

Lactobacillus reuteri is a natural inhabitant of the gastrointestinal tract

and is an excellent probiotic. The organism was originally derived from

breast milk and is available in capsule form at pharmacies and health food

stores and on the Internet. Early studies indicate that this organism can

speed a child's recovery from diarrheal disease and is safe for use in

patients with H.I.V., Dr. Reid said.

Dr. Reid holds a patent on one probiotic product not yet available in North

America but licensed to Chr. Hansen, a Danish company. That company sells

another product, ProbioTek, that is encapsulated to survive oral ingestion

and reach the intestinal tract, where its potential protective action can be

released. It contains four microencapsulated probiotic organisms and is

currently sold in American pharmacies as Flora-Q by Bradley Pharmaceuticals.

Currently, in Dr. Reid's opinion, " you get what you pay for, and in most

cases you're not getting very much. " Once again, caveat emptor.

Copyright 2004

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