When bacteria is good for your body
When Bob Parmelee was bitten by a dog last year, his physician prescribed a hefty dose of broad-spectrum antibiotics to counter any potential bacterial infections. Unfortunately for Parmelee, what should have been merely routine treatment turned out to be overkill. “The antibiotics were so strong they virtually wiped out my intestinal flora,” said Parmelee, a staff research associate at UC Davis.
He began suffering from severe anemia, intense bouts of abdominal pain, and a host of other unpleasant gastrointestinal signs. Then, on the advice of Dr. Robert Backus, a nutrition professor in the UCD School of Veterinary Medicine, he decided to try a bottle of Lactobacillus acidophilus.
“I was taking two capsules a day, equivalent to four or five billion live bacteria, and within a week most of the symptoms went away and I felt a lot better,” Parmelee said. Several weeks after taking the acidophilus, he saw a gastroenterologist at Kaiser who told him to continue taking the pills. Within a few months, the normal microbial makeup in his gut had been largely restored.
What Parmelee had found was “probiotics”—a health craze that has taken Europe and Japan by storm since the 1990s. Hailed by many as the new living drug, probiotics are healthy bacteria that we normally have in our gut to perform essential functions like digestion, immune stimulation and protection from harmful germs.
The human digestive tract contains trillions of bacteria—a population so huge it outnumbers all the cells in our entire body. But this friendly intestinal flora can sometimes be thrown off balance, leading to pretty unappetizing consequences. In that case, probiotics proponents believe supplements of good bacteria can help colonize the gut and elbow out the bad organisms trying to take over, thus restoring balance and preventing disease.
“There is a wealth of basic science that supports the protective effects of some organisms,” said Dr. Thomas Prindiville, a gastroenterologist at UCD Medical Center. “Therefore there are good and bad bugs. The probiotic organisms are those that promote protective or anti-inflammatory responses.”
In contrast to antibiotics, literally “anti-life,” probiotics means “for life.” Derived from living organisms like mold, antibiotics seek to eradicate pathogenic bacteria while probiotics promote the growth of beneficial ones. While the two may seem diametrical opposites, they are actually flip sides of the same coin: Both work by competitively displacing or inhibiting their enemies and wane in effect with removal or adaptation by other microbes.
The first antibiotic, penicillin, was stumbled upon in 1928 by Scottish scientist Alexander Fleming, heralding an era of discovery and development that caused deaths from bacterial infections to plummet. Experts were so sure they had found the miracle cure that in 1969, then-U.S. Surgeon General William Stewart boldly declared to Congress that it was time to “close the books on infectious diseases.”
Little did he know how wrong he was.
By the 1950s, when antibiotics were still new, there was already ample evidence that resistant strains of bacteria were emerging, but it seemed to matter very little then. There was always a new drug in the works to combat them. But by 2000, new classes of antibiotics were no longer being developed and resistance to commonly used antibiotics continues to evolve at an alarming pace.
Making the situation worse is our age of managed health care, where doctors are often pushed to overprescribe antibiotics rather than doing more labor-intensive workups on their patients. Another worrisome trend is the rising number of people who self-medicate with antibiotics as a panacea to all ills. The panic generated by the recent anthrax scare prompted even more people to take antibiotics prophylactically against a disease they will likely never contract.
Yet few are aware that each time antibiotics are used, a microscopic battle for survival of the fittest ensues. The strongest bacteria learn to resist the drug, breeding a host of resistant organisms that then pass their genes on to future generations.
In light of this, the development of probiotics is important not only because of their potential clinical applications, but also because one day they could actually help replace the use of some antibiotics in combating infectious disease.
Although the term probiotics is newly coined, the idea is not: for centuries people have eaten fermented foods like yogurt, and historical records show that some doctors have long advocated the beneficial effects of bacteria in yogurt to treat disease and build up a healthy gut flora.
At the turn of the 1900s, Russian immunologist and Nobel Prize-winner Elie Metchnikoff attributed the unusual longevity of peasants in a Bulgarian village to their habitual consumption of yogurt. Today, scientists are investigating a wide range of problems that probiotics could potentially target. These include lactose intolerance, all kinds of diarrhea-related illnesses, food allergies, liver disease, even cancer.
In the meantime, the bacteriological status of your gut has already become a serious part of the global food business. Probiotics fall under the category of “functional foods”: products that supposedly confer health benefits beyond their normal nutritional value. Manufacturers of probiotics make all kinds of claims—some bordering on the miraculous—on the basis of their live bacteria.
Although probiotics have been largely confined to yogurt and dietary supplements in this country, Europeans and Japanese routinely consume them in cheese, drinks, candy and other foods. Yakult, one of the world’s largest probiotics manufacturers, likes to boast that over 23 million people drink a bottle of its product each day.
There’s definitely evidence that probiotics do work in some cases. It’s been shown that most people with moderate lactose intolerance can eat Lactobacillus-containing yogurt without experiencing digestive upset. To date, the best-established use of probiotics has been in treating acute diarrhea in kids.
There is also some evidence that, when taken regularly, probiotics may exert a prophylactic effect in high-risk populations—children in daycare, for instance—by lowering the incidence of disease. Prindiville, who has done Lactobacillus studies on patients with irritable bowel syndrome, believes probiotics may be effective in managing intestinal problems like traveler’s diarrhea and the diarrhea associated with antibiotic use.
Still, it’s important to keep in mind that most probiotics studies in the scientific literature are far from clear-cut. Much of the research has been inconclusive or had conflicting results, and the general scientific community remains wary of—or simply unaware of—the hype.
“My personal feeling is that, as with other ‘natural’ products, there is some good and lots either unsubstantiated with real research or purely bad,” said Dr. Anthony Philipps, chair of the pediatrics department at UCDMC.
Certainly, much more research on probiotics needs to be—and undoubtedly will be—done. Moreover, since “functional foods” are not regulated by the Food and Drug Administration, it’s important to establish the safety of long-term probiotic use by the public.
“I think the future is quite promising,” said Prindiville. “It’s a bug world—you have 100 trillion bacteria in your colon. The complex nature and diversity of their makeup protect you from all of the enteric pathogens so that when you do get a bad bug, it’s only transient.”