A MICROSCOPIC VIEW OF THIS CHAPTER
• A probiotic is identified by genus, species and strain.
• Probiotic strains can be found in a variety of microbial genuses.
• Lactobacilli love the small intestine; Bifidobacteria love the colon.
• The origin of a probiotic can tell you some of what it does.
• Transient probiotics have health benefits, but do not colonize in the body.
• Different ages require different probiotics.
• Each species of probiotic has its own set of health benefits.
• Multispecies are most effective.
• Different strains of probiotics have different characterisitics.
SORTING AND CLASSIFYING MICROBES AND PROBIOTICS
Considering there are over a quadrillion (1014) microbial species in your intestines, it’s appropriate that we identify the different species and what they do. When discussing types of microbes, we use taxonomical classifications to help identify them. First, the genus, or family name, tells us that the microbe shares a common set of characteristics. For example, Bifidobacteria is the name of the genus and this genus has the characteristic of being able to produce lactic acid, and it has a Y-shape. Second, the species tells us more specifics about the microbe. For example, describing a bacterium as Lactobacillus acidophilus tells you it is of the genus Lactobacilli and the species acidophilus. All acidophilus species share a subset of characteristics that makes them different from other species of Lactobacilli. Third, we can describe a specific bacterium even further by describing the strain, which is commonly noted by a series of letters and/or numbers. For example, E. coli 0157:H7 is a specific strain of bacteria. Each strain of bacteria has its own characteristics that are unique to it alone.
genus > species > strain
Probiotics are not a genus, species or strain. The term probiotic is used to describe a group of microbes that offer benefits to you, the host. Microbes that behave as probiotics can be found in different genuses: Bifidobacterium, Lactobacillus, Streptococci, Enterococcus, Saccharomyces and Lactococci. Of note, not every species in these genera act as probiotics. In other words, not every Enterococcus species is a probiotic. In Appendix 4-1, you will find a list of common probiotic species found in commercial products that are commonly the subject of scientific research. Let’s take a closer look at the probiotics found in these four genera of bacteria.
Probiotics can be found in the Bifidobacteria genus. Bifidobacteria are normal inhabitants of the human colon and are also found in many animal species. In fact, it only takes a few days after birth for the colon to be colonized with Bifidobacteria, particularly breast-fed infants. Bifidobacteria were first isolated in the feces of breast-fed infants. This family of bacteria appears to colonize and remain at stable population levels in humans until advanced age (elderly) when its population numbers seem to decline. Bifidobacteria can produce lactic and acetic acids, and as such are also classified as lactic acid bacteria. Bifidobacteria are also found in the human vagina. Probiotic species in the Bidifobacteria family include B. lactis, B. bifidum and B. longum.
Lactobacilli are another family of bacteria that normally live in the human intestine, mouth and vagina. Capable of producing lactic acid, Lactobacilli are classified as lactic acid bacteria. This ability to produce lactic acid has been put to use in the production of yogurt as Lactobacilli acidophilus is a primary bacteria in yogurt products. Probiotic species in the Lactobacilli family found in the human body include L. reuteri, L. casei and L. rhamnosus.
Streptococci are also found in dairy products. Streptococci thermophilus is commonly used to make yogurt. Some Streptococci species are probiotics. Streptococcus salivarus subspecies, thermophilus, is a probiotic found in the human mouth, throat and nasopharynx and is thought to offer healthy benefits to humans.
Enterococcus is another family of bacteria that occupies both animal and human intestinal tracts. Enterococcus is a lactic acid-producing bacteria. Two species are commonly found in the intestines of humans: E. faecalis (90-95%) and E. faecium (5-10%). These two species of Enterococcus have probiotic effects in humans.
Saccharomyces belongs to the yeast family or genus. Saccharomyces is from the Latin meaning “sugar fungi.” Many members of this genus are considered very important in food production. One example is Saccharomyces cerevisiae, which is used in making wine, bread and beer. Saccharomyces cerevisiae is more commonly known as baker’s yeast. I will leave it up to you to decide which name you’ll use from now on; however, referring to this vital baking ingredient as S. cervisiae may make you sound smart at parties. Saccharomyces boulardii is the principle probiotic yeast noted in the media and in commercial products. S. boulardii is normally beneficial to the body and has been used to treat diarrhea associated with antibiotic use and C. difficile.
Lactococci is another genus that includes some probiotic species. Lactococci are classified as lactic acid bacteria as they can introduce lactic acid to their environment. Lactococcus lactis (formerly known as Streptococcus lactis) is found in dairy products and is commonly responsible for the souring of milk.
You can find a wide variety of these probiotics in foods and supplements around the world. Appendix 4-1 lists probiotic species commonly found in commercial products.
Probiotic Origins
Commercially used probiotic strains have been isolated from vegetable, animal or human origins. The origins of each strain will vary. The origin can help tell you a bit more about the product. A probiotic from animals and vegetables is more likely to be transient. Transient probiotics travel through the intestinal tract, eliciting some health benefits, but they do not attach and colonize in the body. Human strains are typically great colonizers. The more likely a probiotic is to colonize, the greater the resulting duration and potency of its health benefit. NOTE: Some products on the market use soil-based probiotics, which are not usually the same strains as those used in clinical trials and are not of human origin; thus, they may not offer you the same health benefits.
THE TWO MOST POPULAR GENUSES
The two most popular probiotic genuses are Lactobacilli and Bifidobacteria. These are the most common genuses in probiotic foods and supplements around the world. Let’s take a closer look at these two probiotic families.
There are twice as many Bifidobacteria in the human intestinal tract than Lactobacilli. Bifidobacteria reside predominantly in the lower intestine where they elicit most of their health benefits. As the colon or large intestine is the final stage of food digestion it is full of Bifidobacteria’s favorite food: incompletely digested carbohydrates, e.g., inulin, fructoolgiosaccharides, which are also called prebiotics. Bifidobacteria are capable of readily fermenting these carbohydrates. In the large intestine, Bifidobacteria can inhibit the growth of bad microbes via multiple mechanisms including the ability to lower the pH of the environment by excreting lactic acid and acetic acid. Bifidobacteria are also important for the production of thiamine (B1), riboflavine (B2), pyridoxine (B6), folic acid, cyanocobalamine (B12) and nicotinic acid. The B vitamins are required for energy production. If you are feeling sluggish, it is often due to a deficiency in B vitamins. They also play a role in your mood. Bifidobacteria are vital for the proper health of the lower intestine and your feelings of overall wellness.
Both Lactobacilli and Bifidobacteria may be lactic acid-producing bacteria; however, they differ in shape, and they prefer to live in different locations in the human intestinal tract. Lactobacilli are rod-shaped and Bifidobacteria are Y-shaped. Bifidobacteria like to live in the colon, while Lactobacilli like to live in the small intestine.
Both families of bacteria are capable of inhibiting bad microbes in their favored environment; however, their mechanisms can vary slightly. Lactobacilli produce lactic acid but do not produce acetic acid like their Bifidobacterium cousins. Lactobacilli bacteria are also different in that some species can excrete chemicals that act as antimicrobials. Through a number of mechanisms, Lactobacilli can promote the healthy colonization of probiotic species in the intestinal tract. Lactobacilli are also effective at promoting the health of the cells that line the intestines and keep the immune system in line and working correctly. It is the latter of these health benefits of the Lactobacilli genus that are unique to this genus.
Known Species of Lactobacilli and Bifidobacteria
Lactobacillus (Family: Lactobacilli)
Lactobacillus acidophilus
Lactobacillus amylovorus
Lactobacillus brevis
Lactobacillus bulgaricus
Lactobacillus casei
Lactobacillus casei sp. rhamnosus
Lactobacillus crispatus
Lactobacillus delbrueckii
Lactobacillus fermentum
Lactobacillus gallinarum
Lactobacillus jensenii
Lactobacillus johnsonii
Lactobacillus plantarum
Lactobacillus reuteri
Lactobacillus rhamnosus
Lactobacillus salivarius
Lactobacillus sporogenes
Lactobacillus vaginalis
Bifidobacteria (Family: Actinomycetaceae)
Bifidobacterium adolescentis
Bifidobacterium animalis
Bifidobacterium bifidum
Bifidobacterium breve
Bifidobacterium infantis
Bifidobacterium lactis
Bifidobacterium longum
Bifidobacterium regularis (trademarked
name for B. animalis DN173 010)
WHICH PROBIOTIC SPECIES ARE BEST FOR YOU?
In the young, evolving science of probiotics, there are always more questions than answers. Knowing exactly which species are right for you will likely be a question we cannot accurately answer for many years to come. However, there are a few generalizations we can make that can help you find the right probiotic species for you.
GENERA VARY
As these two genera are the most popular on the market, understanding their differences can help determine which one may offer you the best health benefits. Remember where these probiotics like to live. Lactobacilli live in the small intestine and are helpful in treating diarrhea, some inflammation-based conditions, promoting a healthy immune system and improving digestion. Vaginal problems can be targeted with Lactobacilli as this genus likes to live in the vagina and is known to promote health in this area of the body.
You can choose a probiotic based on its preferred location to live in the intestinal tract.
Bifidobacteria live in the colon and thus are very helpful in improving health of the colon, including relieving constipation. We know that as we age the levels of Bifidobacteria in our colon tend to drop resulting in health problems. The result of low Bifidobacteria colonies in the colon of the elderly is an increase in constipation episodes, presence of bad microbes and the production of toxins by these microbes which can be carcinogenic.
As such, ensuring your diet contains the Bifidobacteria genus of bacteria may be beneficial to health in the elderly.
Appendix 4-2 illustrates the presence of Bifidobacteria species in infants and adults.
It is wise to choose a probiotic based on your age requirements.
Notice the change in the makeup of the species present with age. In the elderly, a change in cell receptors or environmental factors may be the cause of the decreased presence of Bifidobacteria in their colon. Children’s probiotic supplements focus on the species known to inhabit a healthy infant’s intestines, such as L. rhamnosus and B. infantis . Supplementing with probiotic species based on age is another way to choose a probiotic.
EACH SPECIES OF PROBIOTIC HAS ITS OWN HEALTH BENEFITS
Different species of probiotics offer different health benefits. For example, despite being from the same genus, L. acidophilus and L. reuteri do not have the same health benefits in the human body. Yes, both have antimicrobial effects, which reduce the presence of bad microbes in the intestines; however, L. acidophilus has additional health benefits including the ability to produce vitamin K and lactase. As such, L. acidophilus has a different set of health benefits than L. reuteri. Does this mean that L. acidophilus is superior to L. reuteri? That is difficult to measure as each species has a different set of health benefits; it is like comparing apples to oranges. L. reuteri can inhibit bad microbes in the intestines, as L. acidophilus can; however, L. reuteri can excrete reuterin, a potent antimicrobial shown in clinical studies to effectively treat cases of Rotavirus diarrhea and H. pylori infections. Thus, both species of Lactobacilli are very beneficial. Each has its own set of health benefits—each set is equally important to overall human health. As you can see, it is not easy to decide which probiotic is better than another.
There probably is no one ultimate probiotic species for health; there is no magic bullet. Each probiotic offers a different set of health benefits. As well, you can get a synergistic effect by having many different probiotic species in your intestinal tract.
In research trials, combinations of probiotics have been found to be more useful than a single species alone. For example, L. rhamnosus and L. reuteri are better at alleviating acute diarrhea than a single probiotic species. Probiotic species work better together than alone. If probiotics could sing to us, perhaps they would sing, “So, happy together.”
STRAINS ARE DIFFERENT
Have you ever wondered why sometimes a species of probiotic appears twice on a product label? When this happens, there is a series of letters and numbers after the species name. This indicates that there are different strains of that probiotic species present in the product. Each species of bacteria, e.g., L. acidophilus, has strains, e.g., L. acidophilus HA-122 and L. acidophilus M92. In other words, when we refer to a species of probiotics, it is actually a group of bacteria strains. Each strain can exhibit different characteristics or health benefits. For example, Lactobacillus acidophilus HA-122 is a particular strain of this species that is particularly resistant to acid. As such, this strain is used in some probiotic supplements that are taken orally and its acid resistance allows it to successfully pass through stomach acid on the way to its preferred destination—the small intestine.
When looking at the ingredient label of a probiotic food or supplements, you can identify the strain by the series of letters and numbers that follow the species name. Particular strains may offer better health benefits than others. Clinical research papers will specify which strain was used.
If you want to use probiotics to target a particular illness, be sure to get the exact strain indicated in the research studies. A similar strain may not produce the same health effects.
As the science of probiotics is still in its infancy it can be difficult to find a clinically researched probiotic strain on the supermarket shelves for every disease condition. Only some conditions have been sufficiently studied to know which strains or even species are most effective.
Researchers have investigated whether particular probiotic species are effective against a specific disease conditions. For example, L. plantarum has been clinically studied for its effects against irritable bowel syndrome. L. salivarius has been studied to see if it inhibits the growth of Helicobacter pylori, a bacterium found in the stomach and associated with some ulcer formation. In both cases, researchers found these specific probiotic species to be effective against the targeted disease condition. There are many examples of studies where probiotic species have been used to target a disease condition; however, not every species has been tested against every disease. The result is some areas of diseases are well studied and others less. In Part II, we will dive into the research in this area. We’ll investigate what scientists have found when they have researched the effect probiotics may have on a wide variety of disease conditions. A short summary of this information is captured in Appendix 6-2.
Most of us are looking for a particular strain to make our shopping experience a little easier. What shall we do then? Remember that a healthy, balanced intestinal microflora can offer you many healthy benefits. Experts are recommending the use of a variety of probiotic species (and strains) to promote optimal health.
MULTI-SPECIES PROBIOTICS ARE BEST
A multi-species probiotic is highly recommended based on current knowledge about probiotics and their health effects. Why is this? Combinations of probiotic species have been found to have a synergistic effect. In other words, species of probiotics work together to give a greater health benefit than a single species can alone. Let’s look at an example. A combination of L. casei, L. plantarum, L. acidophilus, L. bulgaricus, B. longum, B. breve, B. infantis, S. thermophilus, known as VSL#3, has been used in a number of clinical trials along with single probiotics. In most cases, the combination of a number of probiotics offered an increased health benefit (synergisitic effect). Multi-species supplements are better for your health.
Most multi-species probiotic products on the market contain Lactobacilli and Bifidobacteria species, but new species and genera are being assessed for future use. The future will likely unveil many more probiotic species that may offer even greater health benefits. Watch for new technology in the future that increases the viability of probiotic species to enable more convenient ways for ingestion including more shelf-stable techniques to be used in both supplements and foods.
Consuming a combination of probiotic species can offer a wide range of health benefits.
SUMMARY
A probiotic species is identified by its genus, species and strain. The genus is a family name like Bifidobacteria. A species such as acidophilus identifies that the probiotic has a set of characterisitics. Each strain of probiotic has its own unique characteristics. Which probiotic species is right for you? You can choose a probiotic based on its preferred location to inhabit in the body or by your age requirements. For example, Lactobacilli love to live in the small intestine and Bifidobacteria love to live in the colon. In some disease conditions, researchers know which specific species offers health benefits. However, there is much research left to be completed. If choosing a probiotic strain based on its effects in clinical research, be sure to purchase the exact strain—different strains have different effects. Experts agree that having a healthy mixture of a variety of probiotic species in the intestinal tract can provide the best health benefits. In other words, multi-species probiotics may be the right choice for you. In Chapter 18, we’ll discuss in more detail how to find the right probiotic food or supplement for you. In Part II, we’ll discover what health benefits probiotics can offer and which offer the best health benefits for which disease conditions.
