Are probiotic products really effective?

Although certain bacteria help treat some intestinal problems, they are not known to be of any benefit to healthy people.

By Faris Jaber, the article is published with the approval of Scientific American Israel and the Ort Israel network 05.09.2017

Go into any grocery store and you will most likely find quite a number of products"Probiotics” full and brimming with beneficial bacteria that are supposed to treat everything from constipation to obesity and depression. In addition to foods traditionally prepared using cultures of live bacteria (such as yogurt and other fermentation products), consumers can now buy capsules and pills, fruit juices, breakfast cereals, hot dogs, biscuits, sweets, granola bars and dog food, all of which are probiotic. In fact, the popularity of probiotic products has grown in recent years to such an extent that manufacturers have begun adding microorganisms to cosmetics and mattresses as well.

However, a closer look at the scientific research behind the bacteria-based treatments shows that most claims about the health value of probiotics are nothing more than fads. Most of the studies done to date have not been able to find any benefit to the north in healthy people. The bacteria apparently help people who suffer from specific intestinal problems. "There is no evidence to suggest that people whose digestive system is functioning properly may derive any benefit from consuming probiotics," says Matthew Chorba, a gastroenterologist at Washington University in St. Louis. "I wouldn't recommend them to someone who isn't suffering from some sort of distress." Emma Allen-Workow, a microbiologist from the University of Guelph in Ontario, Canada, agrees with his words. Essentially, she says "the claims being made about probiotics are overblown."

The numbers game

This scenario is well known from the past, especially in the context of vitamin supplements that decades of research have shown to be completely useless for most adults, and in some cases, even dangerous and linked to increased rates of lung cancer, breast cancer andprostate cancer. But this information did not stop marketers from promoting a new nutritional craze. According to a survey by the National Institutes of Health, the proportion of adults in the US taking probiotic supplements or similar products (mostly non-digestible fibers that encourage the growth of gut bacteria) quadrupled between 2007 and 2012, from 865,000 to approximately four million. . San Francisco-based business consulting firm Grand View Research estimated the global probiotics market at more than $2015 billion in 35, and predicts it will reach $66 billion in 2024.

The mass craze surrounding probiotics is fueled in large part by the growing interest both science and the public are discovering in the human microbiome: the overlapping ecosystems of bacteria and other microorganisms that reside all over our bodies. The human digestive system contains about 39 trillion bacteria, according to the latest estimate, and most of them reside in the large intestine. In the last fifteen years, researchers have recognized that the majority of The commensal bacteria These are essential for health. As a whole population, they push harmful invaders out of the system, break down fiber found in food into more digestible components and produce vitamins such as vitamin K and B12.

The idea according to which the consumption of probiotic products can increase the ability of bacteria that live inside us and are already functioning well to improve our general health, is questionable for several reasons. Manufacturers of probiotics usually choose specific strains of bacteria for their products because they know how to grow them in large quantities, not because they are adapted to life in the human gut or known to contribute to health. The particular varieties of Bifidobacterium או Lactobacillus that are usually found in yogurt of all kinds and also in pills are not necessarily of the same species that can survive in the very acidic environment that prevails in the stomach, pass it safely and settle in the intestines.

Even if some of the bacteria in a probiotic product manage to survive their passage through the stomach and reproduce in the intestines, the chances are that their number will be too small to significantly change the overall composition of the human intestinal population. The human intestine contains tens of trillions of bacteria, while a typical serving of yogurt or a probiotic pill contains between one hundred million and several hundred billion bacteria, a fraction of a percent compared to the population of bacteria present in the intestine. Last year, a team of researchers from the University of Copenhagen published an article reviewing seven randomized, placebo-controlled trials (the most stringent studies that scientists know how to conduct), and tested whether probiotic supplements - including biscuits, milk-based drinks and capsules - change the diversity of bacteria in stool samples. Only one study - in which 34 healthy volunteers participated - found a statistically significant change, and no evidence was found that it resulted in an improvement in the subjects' health. "A probiotic product is ultimately a drop in the ocean," she says Shira Doron, an infectious disease specialist at Taft Medical Center. "The intestines always contain bacteria in larger numbers by several orders of magnitude."

A real benefit

Despite the growing feeling that probiotic products offer nothing real to people who are already healthy, researchers have found that they can benefit people with certain medical conditions.

Thus, for example, in the last five years, an analysis of several dozen studies led to the conclusion that probiotics can prevent some common side effects associated with antibiotic treatment. When doctors prescribe an antibiotic, they know that the drug may wipe out entire populations of beneficial gut bacteria, along with the harmful bacteria they are trying to destroy. In most cases, it is enough for the body to absorb some bacteria from the environment and they will regenerate Microbiome healthy. But sometimes it happens that the niches that have been emptied are filled with harmful bacteria that secrete toxins, cause intestinal infections and cause diarrhea. The addition of yogurt or other probiotic food - especially those containing Lactobacillus type bacteria - during and after antibiotic treatment, apparently reduces the chances of developing such occasional infections.

In 2014, the Cochrane Research Partnership – an independent network of experts who act as strict judges of medical research – published a review article showing that probiotic products may be particularly beneficial in hospital neonatal intensive care units. Adding beneficial bacteria to their feeding program greatly reduces the risk for necrotizing enteritis - necrotizing enterocolitis, a severe and sometimes fatal intestinal disease, the cause of which is still unclear, which primarily affects premature babies, and especially the smallest and least mature of them. Researchers believe that many cases of the disease begin with the infection of random bacteria in the intestine of the newborn, which has not yet fully developed. As the disease progresses, the intestinal wall tissue becomes inflamed and in many cases begins to die, leading to perforation of the intestine and flooding of the abdominal cavity with pathogenic bacteria that multiply in dangerous quantities. The researchers estimate that 12% of premature babies who weigh less than 1.7 kg may suffer from necrotizing enteritis and that 30% of these do not survive. The standard treatment includes a combination of antibiotics, intravenous feeding and surgery to remove the dead tissue. It is possible that probiotic food prevents the disease by increasing the number of the beneficial bacteria, and pushing out the harmful ones.

It also appears that probiotic products provide relief to sufferers from irritable bowel syndrome, a chronic disease characterized by abdominal pain, bloating, and frequent diarrhea or constipation (or a combination of both). A 2014 review summarizing more than 30 studies, published in the American Journal of Gastroenterology by an international team of researchers, found that in some cases, probiotics relieve symptoms of irritable bowel syndrome for reasons that are unclear, although they may inhibit The culture of harmful bacteria. However, the researchers noted that they did not have enough data to recommend specific strains of beneficial bacteria. The microbiologists caution that one promising study testing a single strain of a particular species of bacteria should not be taken as proof that all probiotic products work equally well. "Strains of bacteria are very different from each other in their genetic traits, and each person has a different population of gut bacteria," says Allen-Verko. "There will probably never be one probiotic product that suits everyone."

But what if researchers could design probiotic products tailored to the treatment of individuals? Many researchers think that personalized probiotics are the most promising route for patients whose microbiome is damaged. Last year, Jens Walter and his colleagues at the University of Alberta in Canada published a study that provides a glimpse of this possible future. The researchers decided to examine what was required to cause bacteria from a certain probiotic product to successfully colonize the intestines of 23 volunteers. They chose a certain strain of the bacterium Bifidobacterium longum that early studies showed was capable of surviving in the human intestine. In their study, the volunteers drank every day for two weeks a drink that contained 10 billion live bacteria of this strain, or a placebo drink that contained a glucose-based food additive (maltodextrin). Stool samples taken from them at regular intervals showed a much higher level of B. longum than is typical in the participants who did not drink the placebo.

Amazingly, in seven people, these levels of the bacteria remained the same for more than five months after treatment ended. "We didn't expect the bacteria to survive more than a few weeks at all," says Walter. A subsequent analysis revealed that these people started the experiment when the levels of bacteria in their intestines were lower than normal. In other words, there was an empty space in their intestines that the bacteria in the drink filled. This is exactly the finding that doctors need to create more effective probiotic products, and recommend them. If a doctor knows that in a person suffering from severe diarrhea, the population of beneficial bacteria is too small, for example, he can prescribe a product that contains the missing strain and thereby increase the chances of success of the treatment.

"The key is in adopting an ecological point of view," says Walter. "We need to find out which bacteria are able to survive in the ecosystem that prevails in a given intestine." Put another way, treatments for microbial-related diseases may succeed if they work in concert with, not just against, the many microscopic citizens that live in our bodies.