Dr. Cary Nelson
I’m a board certified family practitioner
Founder, Probiotic America
From yogurt to youth-enhancing creams, probiotics seem to be the latest cure-all ingredient. But what is it? And how can they really help you?
In the most basic of terms, probiotics are microorganisms, such as yeasts and bacteria, that can be consumed to achieve positive effects on your digestive and overall health. In May of 2002, the World Health Organization (WHO) conferred with expert groups of academic scientists and representatives from the probiotic industry to create their “Guidelines for the Evaluation of Probiotics in Food”.
According to the WHO, the definition of a probiotic is as follows: "Live microorganisms which, when administered in adequate amounts, confer a health beneﬁt on the host."1
Beyond that, to be considered a true probiotic, the organism must be a defined microbe that has been identified and classified by genus, species, and strain level. This classification is critical. Regulation and control are critical for identifying the potential benefits of any particular type of probiotic. Lastly, but perhaps most importantly, probiotics must be deemed safe and tolerable for ingestion by the intended consumer.2
It’s understandable if the idea of eating bacteria doesn’t sound healthy or appealing. However, humans and animals are largely made up of bacteria. In fact, it’s believed we have the same amount of bacteria as human cells! It’s no wonder our bacteria in our body weighs more than our brain (3 lbs!).3
Because the body is full of both good and bad bacteria.
The good guy bacteria play a large part in many of the body’s functions and processes—including immune responses and digestion.4 Oftentimes, that desired effect is related to digestion. Probiotics have certainly made a name for themselves in recent years for their ability to regulate and assist with all things related to the belly’s business. Digestive health is a major contributor to overall good health. Naturally, probiotics have become a popular addition to many people’s personal health routines.5
To say that probiotics are used to aid consumers with their digestion is a generalized statement. In reality, there are numerous benefits from consuming probiotics. Many pluses associated with taking probiotics have to do with the digestive process, such as:
In addition to these digestive benefits, probiotics have been found to be useful in managing and preventing eczema, preventing and treating urinary tract and bladder infections and more.8
The effects of probiotics have been studied and documented for generations, but it was not until recently that probiotics reached the public consciousness. Now, they’re highlighted in mainstream media and product advertisements marketed for their gut-boosting benefits.
At this time, probiotics are available to consumers in a number of forms. Most commonly, they’re associated with dairy products, such as yogurt and kefir. Good natural sources of probiotics are also found in many fermented foods like kimchi, kombucha, miso soup, and sourdough bread. Commercially, probiotics show up in dark chocolate, pickles, snack bars, and certain kinds of teas.9, 10
Once you ingest a product that contains probiotics, the bacteria go through the digestive process. Ideally, the probiotics ultimately find their way to the lower gut, where they can contribute to the health of the host. Unfortunately, the digestive system is rigorous and often indiscriminate, so much of the “good” bacteria ingested are lost to the process. For the bacteria that survive the process and establish a presence in the lower gut, they can be distributed to the intestines, the kidneys, the liver, and anywhere else they can be utilized appropriately based on the particular strain.11
The body generally seeks to rid the body of both the good and the bad guys when it comes to bacteria. The digestive process is accomplished with stomach acid—which is incredibly strong and quite effective at breaking down compounds and expelling unwanted matter from the body. The stomach acid breaks down everything that finds its way into the stomach, including good bacteria.12, 13
According to some studies, there are actions that can be taken, such as ingesting the probiotic on an empty stomach or with a meal.14 Researchers continue to study this theory to determine whether this helps. Another approach is to eat a diet rich in fiber. The fiber, which your body can’t digest, feeds the bacteria in the large intestine. A lack of fiber can result in the good bugs starving, thereby minimizing their full potential.15
While most recognize that the popularity of probiotics came to be in the 21st century, the establishment of probiotics as an actual scientific concept was in 1907. The idea that that microbes and bacteria affected the internal workings of humans and animals was first proposed by Russian zoologist Élie Metchnikoff. He went on to become known for his research and studies in the field of immunology. In fact, he was awarded the 1908 Nobel Prize in Physiology or Medicine. After observing Bulgarian peasants living longer, healthier lives than other peoples from the region, Metchnikoff proposed the theory that the peasants’ custom of eating large amounts of yogurt may be linked.16
"The dependence of the intestinal microbes on the food makes it possible to adopt measures to modify the flora in our bodies and to replace the harmful microbes by useful microbes.” - Élie Metchnikoff, Nobel Prize winner.17
Technically, the history of probiotics can be traced to the beginning of mankind’s understanding of the fermentation process, but the first time the applications or medicinal properties of the bacteria were considered is certainly a more relevant occurrence. Unfortunately, it is also just as difficult to pinpoint. There are mentions of using fermented milk to treat intestinal issues in the Bible and in other sacred books of comparable era. Many Middle-Eastern and Asian societies of the time have also been found to use fermented or “soured” milk for intestinal health.
There is also documentation from thousands of years ago in ancient Rome of widespread use of fermented dairy products for medicinal purposes. Pliny the Elder, a renowned naturalist during the Roman Empire era, allegedly recommended drinking fermented milk products to treat intestinal issues.18, 19
The therapeutic benefits of these products were recognized and accepted by many cultures worldwide—even though it was well before science could define and explain the benefits of good bacteria.20
A correlation between digestive tract bacteria and gastrointestinal health was found in 1899 by Henry Tissier, a French scientist. Tissier discovered a bacteria called bifidobacteria in the intestines of a number of infants in the study. Whenever he found an abundant supply of bifidobacteria in an infant, he found they had significantly fewer gastrointestinal problems and far fewer instances of diarrheal illnesses.21
Not long after Henry Tissier made his mark, Elie Metchnikoff’s work in the field of immunology started to get recognized. Metchnikoff, like Tissier, was a research scientist at the Pasteur Institute in Paris, France. He was allegedly seeking a biological “fountain of youth,” or compound that would grant eternal youth. This was a popular pursuit of scientists of the time. And despite the seemingly ridiculous theory, the scientific discoveries it led to made it worthwhile in the end.
At the time Metchnikoff was at work, it was already understood that certain “bad” bacteria existed in the digestive tract. Metchnikoff was studying lactic acid bacteria and came to believe that it actually produced a form of protection or reversal of a certain strain of bad bacteria. Metchnikoff soon began studying rural Bulgarian peasants and their propensity to live to very old ages—regardless of poverty and living in a terribly harsh climate.
He concluded that the fermented milk products they drank contributed greatly to their increased life expectancies.22
Metchnikoff published his findings in the book, “The Prolongation of Life: Optimistic Studies”. In the book, he makes the proclamation that ingesting microorganisms could have substantial health benefits in humans.23
For his studies on immunity, including how good bacteria can help, he was awarded the 1908 Nobel Prize. He was commended for essentially demonstrating that intestinal illness and the ill effects of harmful microbes can be neutralized by the introduction of beneficial microbes.24, 25 Today, Metchnikoff is considered the grandfather of modern probiotics.
Almost a decade after Metchnikoff’s work gained acclaim, German scientist Alfred Nissle began exploring the possible applications and benefits of probiotics. During his research, Nissle was able to isolate and identify a new bacterial strain, now known as Escherichia coli Nissle 1917 (EcN). Nissle subsequently went on to use the bacteria in successfully treating intestinal diseases, including diarrhea, and it is still being used in similar capacities today.26, 27
Indeed, the term “probiotics” is general. It refers to countless probiotic strains found in nature.
The human body alone houses more than 500 different known probiotic strains. 28
While it would be very difficult to become personally familiar with all of the strains that exist, it is important to be aware of as many as you can. Having a diversity of probiotic strains in your body has been linked to good digestive health and the prevention of obesity and other health issues.29, 30
Here are some of the most well-known strains of probiotics:
Obviously, it is not enough to just know the names of different strains. Each strain has very specific effects and applications for the human body and its functioning.
For example, Lactobacillus Rhamnosus gg is a “good” bacteria and has been proven to provide more than 44 health benefits.31 It is considered particularly effective at intestinal wall adhesion, which helps the body clear itself and cultivate other “good” bacterial strains. The end result of this cultivation is a stimulation and invigoration of the immune system.32
Similarly, another “good” bacterial strain, Bifidobacterium Lactis also has been proven to enhance immunity and improve digestion, and it has also been known to fight tumor growth and lower cholesterol.33, 34, 35, 36, 37, 38
It is typically located in the intestines and colon and is tasked with processing and breaking down body waste and assisting with the body’s absorption of vitamins and minerals.
Bifido Infantis is, no surprise, an important bacterial strain for human beings during their infancy. In fact, it is one of the first probiotics a mother passes to her baby. Many physicians even recommend that pregnant women supplement their daily intake. As you get older, it continues to play a role in your body, as it helps improve digestion and contributes to the prevention of infection and illness. It also has been shown to increase production of certain acids in the digestive tract and vagina which protect against foreign bacteria and parasites. This actually helps prevent kidney stones and allergies.39
Lactobacillus helveticus is used throughout the world, but particularly in Switzerland, to reduce blood pressure, increase serum calcium levels in the blood, improve sleep patterns, and fight bone loss.40, 41, 42, 43
Perhaps the most well-known and thoroughly researched probiotic strain is Lactobacillus Acidophilus. This strain was first isolated by Metchnikoff, the Nobel Prize-winning scientist in the 1890s. Subsequent studies have found that Lactobacillus Acidophilus could be a critical element to human health and survival. This one probiotic strain alone has been shown to help not only with digestive functioning, but also to fight infections, reduce allergy symptoms, improve blood pressure and cholesterol, and assist in infant development.44, 45
As is the case with most natural remedies, probiotics have been met with a fair share of cynicism. However, among the scientific community, including the National Institute of Health, probiotics are confirmed to help with digestion issues. Probiotics linked to treating other issues are still being researched but initial results are promising.46
Much of the controversy surrounding probiotics comes from questions about the regulation of probiotic products on the market. The general feeling is that the products and claims associated with the products have been developed too quickly for the existing regulatory processes to keep up and meet the minimum required regulatory needs of the consumer population.47, 48, 49
Finally, some cynicism has been generated by a few manufacturers of probiotic products. A small number of isolated high-profile incidents have occurred wherein companies have marketed their products using claims and descriptions that have not been fully substantiated by the medical and scientific community. These high-profile cases have, unfortunately, left an indelible mark in many consumers’ minds when it comes to probiotics.50, 51, 52
The fact is, many claims about probiotics have been verified and proven scientifically, but many others have not yet been. It would be a terrible misconception to believe that probiotic bacteria have no proven benefits, but it would also be irresponsible to believe every claim made by product manufacturers. Consumers should be vigilant in their research and attention to detail when considering any health or wellness product.
As established, probiotic intake is critical to maintaining good gut health. The knowledge of this fact leads many concerned people to seek out supplements and products that boast the ability to provide extra probiotic strains to the body.
Interested in maximizing the probiotic potential in the foods you eat? There are a number of probiotic-rich foods you can add to your diet, such as:
Most of these foods contain different probiotic strains. It’s important to diversify one’s intake. Therefore, a diet complete with a variety of probiotic-rich foods is most effective. That being said, there are also benefits to considering adding more probiotics to such a diet with the use of safe, effective supplemental products.
Perhaps the food most commonly associated with probiotics is yogurt. Some of the first and most prominent supplemental products were yogurts and yogurt-based, and they got the discussion started about the benefits of probiotics. Beyond those products, which typically have additional probiotics added, yogurt, in general, contains naturally occurring "good" bacteria.54
Yogurt has been shown to assist in the maintenance of gut health and can treat diarrhea, gas, and other digestive problems.55, 56
When many people hear that yogurt is packed with probiotics, they immediately think that perhaps cheese has similar properties. In reality, this is only somewhat true. While not every cheese is considered a significant contributor to one’s probiotic intake, there are a number of softer, fermented cheeses, such as swiss, gouda, Parmesan, and cheddar, which do have significant concentrations of the “good” bacteria. Not only that, but research finds that, while much of the probiotics consumed by a person are lost during the digestion process. However, some withstand and interact and potentially boost the immune system.57
Another food commonly eaten in the western world that has a significant probiotic content is sourdough bread. Again, not every type of bread has probiotic qualities. Sourdough bread, in particular, is made with sourdough starter, a compound that functions much like yeast, which contains plenty of “good” bacteria.58
Pickles are another commonly consumed fermented product—particularly sour pickles. The fermenting process provides them with their beneficial qualities, but only natural processes, which utilize sea salt and water in lieu of vinegar, create the desired bacteria.
Similarly, pickled cabbage products, including sauerkraut and the Korean staple, kimchi, also have ample probiotic contents, which help with immunity and can fight infection.59, 60
In addition to kimchi, Southeast Asian cuisine has numerous products and foods that are rich in probiotic bacteria. For example, miso soup—a popular breakfast food in Japan—has become commonly consumed in the Western world, particularly in Japanese and sushi restaurants. This soup, made from fermented soybean paste, has been known to promote good digestion.61
Kefir is another probiotic-filled product that has become popular at U.S. supermarkets in recent years. Kefir is a fermented dairy drink from a grain that originates from Russia. It is a bubbly, thick, creamy, tangy beverage that is much like yogurt, but contains its own unique probiotic strains.62, 63
Another product that has also made progress in gaining public awareness in the west is tempeh. With high probiotic content and large amounts of non-animal protein, it is an excellent meat replacement. Tempeh is made from a base of fermented soybeans.
It is Indonesian in origin and has a nutty flavor. The probiotics in tempeh are a natural antibiotic and actually fight certain “bad” bacteria.
Probiotics and bacteria in general are typically considered safe, but certain varieties and concentrations may cause unwanted bacteria-host interactions and side effects. Because of this, the WHO (World Health Organization) stresses that serious consideration be given to the testing and assessment of the microorganisms for their potential benefits, applications, and dangers. The factors most important to monitor include: detecting antibiotic-resistant patterns in the organism; recognizing side-effects in animals and humans; detecting the presence or stimulation of metabolic activity in the test subject; and making note of any adverse or negative reactions in the subjects.64
Lastly, testing is being conducted to determine how the reaction varies with increased concentrations of the probiotic. Additionally, it is possible for one strain to provide a variety of reactions or benefits to a host at differing concentrations.65
Research on the effects of probiotic use are staggeringly positive, so they should be included in your diet. But what type of probiotic supplements are best? Fortunately, the probiotic marketplace is rich and diverse, so there are many wonderful products out there. There are some ineffective products out there as well. It is important to know the basics of what you should look for when considering a probiotic product. Here are some tips:
The product should incorporate multiple types of strains, such as Lactobaccilus plantarum, Lactobaccilus acidophilus, Lactobaccilus brevis, Bifidobacterium lactis and Bifidobacterium longum.66
Most high-quality probiotic supplements either should be refrigerated or the bottle’s label should clearly indicate the bacteria will survive on your shelf without refrigeration. Unfortunately, if it’s been sitting on the shelf and the label says nothing about ‘no refrigeration needed’, it’s quite possible much of the bacteria has already perished. If you’re curious to see if a probiotic actually has live bacteria, you can do this simple milk test:
Look for CFU (Colony Forming Units) count on their labeling, which indicates how much of the probiotic bacteria will divide and create colonies of additional ‘good’ bacteria. A good range for daily supplementation is 10-30 billion CFUs.
Make sure your probiotics are encased in a capsule or enteric coated because stomach acid can zap the amount of CFU’s available.
With the many factors for comparison in mind, an educated consumer might start with a probiotic digestive health capsule. Probiotic products are also available in the form of fermented drinks, such as kombucha, which can substitute for unhealthy soda and other sugary drinks. Kefir is a popular drink in many parts of the world and can boast up to 40 strains of bacteria!
Another drink, Dong Quai, has been gaining a lot of notice for its use as a treatment to increase fertility and prostate health.
Perhaps the most popular probiotic product is yogurt. Since plain yogurt is healthy in its natural state, probiotic-enriched yogurt is an effective, tasty way of getting your daily dose of probiotics.
Since the success of a handful of early entries, the number of probiotic-enriched products available in the market has exploded in the past decade. The marketability of these products led to an increased interest in the field, which in turn led to a number of studies into the effectiveness of various bacterial strains.
In addition to the WHO’s studies and discussions, there has been a flurry of research on the effects probiotics have on the health of consumers. Studies on the effects and benefits of gut bacteria in particular have exploded in recent years, with scientists around the world racing to be the first to discover a heretofore unknown beneficial reaction between a strain of bacteria and its host.
In 2015, for example, a group of researchers at the University of Maryland School of Medicine were looking into a well-known microbe, a bacteria known as lactobacillus rhamnosus GG (LGG). While it was known that LGG had many useful properties — specifically with weight loss, and the treatment of skin disorders, intestinal issues, and respiratory problems — scientists were still unsure of how it produced those beneficial results.
The researchers discovered that the LGG bacteria were actually acting as a facilitator and, in doing so, were effectively modifying or changing the actions of the other bacteria in the gut. This recent study could lead scientists to newer, more effective strategies for achieving gut health.67, 68
Why are more people using probiotic supplements now?
Due to increased stress, changes in lifestyle, and problems with modern diets, including excessive sodium, sugar and trans-fat consumption, the average person deals with significant gastrointestinal and digestive distress during their lifetime. Coupled with the increased consumer awareness of the benefits of probiotics and the huge amounts of money spent by companies advertising their specific probiotic-enriched products, there is a growing interest and adoption of the philosophies associated with the probiotic movement. In fact, the probiotics market is expected to grow greatly over the coming years. It’s projected to be generating over $64 billion in sales by 2023.69
Probiotics are usually associated with the treatment of digestive and gastrointestinal issues, but they have been linked to positive outcomes when used to treat a number of other symptoms as well. For example, probiotics are often given to breastfeeding mothers to help prevent eczema in the child.70, 71
Here are a few more things probiotics seem to help as well, with a link to a study:Slowing Growth of HIV
Prebiotics are compounds found in food, like probiotics, that act in conjunction with probiotics to assist with digestive and overall health. Think of them like fertilizers for your ‘internal garden’ aka good bacteria.
They act as promoters or cultivators of the "good" bacteria.72, 73
Prebiotics include fructooligosaccharides and galactooligosaccharides.74 They can be found in significant concentrations in foods like onions, leeks, garlic, bananas, asparagus, soybeans, and artichokes.75
Every day, it seems that new uses and applications for prebiotics and probiotics are being discovered, theorized, and tested. Their existence and function is not in doubt, but the understanding the extent of how they help other ailments and exactly what they do is still a work in progress. However, with all the news about how important good bacteria in your gut is for health, it does confirm what Hippocrates believed thousands of years ago: “Disease begins in the gut.”