The most common types of probiotics are mainly from the genera Bifidobacteria and Lactobacilli. Many well-known probiotics share health effects like boosting immunity and fighting off infections. Some benefits may be specific to certain probiotic species or strains.
Probiotics are live microorganisms that have demonstrated health benefits when taken in sufficient amounts. With so many probiotics available in today’s marketplace, selecting the best probiotic for your individual needs can be overwhelming. It may help to understand the most common probiotics and how they act in the body.
Understanding Probiotic Species and Strain Names
Probiotics are divided into categories, including genus, species, and strain. Genus is the broader category of classification, while species are groups within a genus that share common features.
If we imagine a genus encompassing all domestic cats and one with all domestic dogs, then the species within the dog genus would be groups of dog breeds sharing common traits, like Retrievers or Spaniels. Strains would be equivalent to individual dog breeds, with their own specific characteristics, like Labrador Retrievers and Golden Retrievers within the Retriever group.
Just like Retrievers are known for certain attributes, the various species of probiotics within each genus can have different effects in the body and are generally grouped by traits with significant health effects, like the ability to fight certain pathogens or produce vitamins.
Every organism, including probiotics, has a scientific name that includes its genus (the first, capitalized, part of its name) and species (the second, lowercase, part of its name), and subspecies (abbreviated subsp.), if applicable. Microorganisms like probiotics can be further classified into strains, expressed alphanumerically, which may have unique properties.
Example: Lactobacillus acidophilus W55 belongs to the genus Lactobacillus, the species acidophilus, and the strain W55.
Common Categories of Probiotics
The most common genera of probiotics are Lactobacillus, Bifidobacterium, Saccharomyces, Streptococcus, Enterococcus, Escherichia, and Bacillus, with species of Lactobacillus and Bifidobacterium being used most often.
Shared benefits of these good bacteria include beneficial effects on the immune system, vaginal and urinary tract infections, dental cavities, and eczema in children. Other studies have revealed further wide-ranging effects of probiotics, including reductions in the duration and severity of upper respiratory infections and positive impacts on blood glucose levels, lipid levels, and measures of body fat.
Probiotics are perhaps most widely known for their impact on gut health. In the gastrointestinal (GI) tract, their effects include enhanced digestion, increased absorption of some micronutrients, and reduced incidence and severity of diarrhea from various causes.
Health benefits can vary depending on the genera and species of a probiotic. Among species, different strains may also have varying effects. Certain probiotics are able to enhance the health of the microbiota, improving immunity, reducing inflammation, enhancing the intestinal barrier, and inhibiting bad bacteria and other pathogens. Additionally, some probiotic strains have been linked to positive effects on the brain, including improvements in mood, attention, and memory.
Bifidobacteria are widespread in the environment and in the intestines of many animals, including humans. They’re the first colonizers of the infant gut microbiota.
Some common species include:
- B. bifidum
- B. animalis
- B. breve
- B. longum
- B. adolescentis
Bifidobacteria have been associated with positive health impacts in the GI tract, including improved lactose digestion, prevention or reduction of diarrhea, and reduced symptoms of irritable bowel syndrome (IBS). They’ve also been linked with improved lipid levels.
B. breve, B. longum subsp. infantis, B. bifidum and B. longum subsp. longum are the most common Bifidobacteria in human infants. Newborns receiving breast milk have higher levels of these helpful bacteria in their gut. These probiotics have been associated with a stronger intestinal barrier and protection against infection and may affect metabolism.
Some species of Bifidobacteria, including B. bifidum, B. infantis, B. breve, and B. longum, are able to synthesize B vitamins and vitamins C and K. They’ve traditionally been used in food processing, particularly for culturing fermented dairy products. They may also aid the absorption of minerals by lowering acidity in the stomach.
Lactobacillus bacteria are known for producing lactic acid and have been used for centuries in food processing, particularly to culture dairy products. The production of lactic acid and other metabolites has been linked to Lactobacilli’s positive health effects.
Some common species include:
- L. acidophilus
- L. plantarum
- L. rhamnosus
- L. reuteri
- L. casei
- L. delbrueckii subsp. Bulgaricus
- L. gasseri
- L. fermentum
- L. johnsonii
- L. paracasei
- L. salivarius
Lactobacilli are important colonizers of the digestive tract, the mouth, and the vagina. Some species have been linked with improved digestion of lactose and micronutrients. They’ve also been associated with a reduced risk of antibiotic-associated diarrhea and vaginal infections.
Other potential health effects of Lactobacillus species include prevention or improvement of eczema in children, lower cholesterol levels, and improved weight loss in obesity.
The Saccharomyces genus encompasses several species of yeast. Some species are found in soil or plant material, while others have been hybridized for industrial uses such as brewing. They are also found in the human GI tract.
The yeast probiotic Saccharomyces boulardii is one of the most well-studied probiotics, mainly for its use in GI disorders. It is a hardy species with a better ability to survive high temperatures and the low pH encountered in the GI tract than other species.
The closely-related yeast Saccharomyces cerevisiae has a long history of use in baking and brewing but doesn’t seem to offer the same health benefits and can act as a pathogen in immunocompromised patients. Because of this, yeast-based probiotics should be avoided in critically ill or immunocompromised patients.
The primary microbiota in the environment, species of the Bacillus genus are typically found in soil, although they’re also found in air and water, some fermented foods, and animal and human GI tracts.
Lifestyle changes in developed areas, including increased hygiene and processed food consumption, have reduced exposure to these bacteria. Bacilli, also known as spore-forming probiotics, are known for their ability to survive harsh conditions.
Bacillus species can be found in the fermented foods kimchi, natto, and some fish sauces, as well as juices and raw fruits and vegetables.
Common species of Bacilli include B. subtilis, B. clausii, and B. coagulans. Commercially available strains are mainly from the well-researched subtilis species. There are also household chemicals available with Bacilli probiotics due to their antimicrobial effects.
Benefits of Bacilli include restoration of gut microflora, anti-pathogenic, anti-inflammatory effects, production of vitamins, including B vitamins, carotenoids, and vitamin K, and secretion of digestive enzymes. They’ve also been shown to fight infections in the GI and urinary tracts. One trial found that a strain of B. coagulans led to significant increases in another strain of beneficial bacteria and increased immune function in older adults.
Although Bacillus species have a long history of consumption, there are some potential concerns with using them. Some species produce toxins and act as pathogens or carry genes for antibiotic resistance. Some formulations have been found to be contaminated with pathogenic microbes, so it’s important to choose a product from a manufacturer with good quality control.
10 Common Probiotic Species
Among the common genera of probiotics, certain species have been researched more extensively than others for their potential health benefits. The following are among the most well-studied:
1. Bifidobacterium animalis
This species is commonly found in the environment and in the GI tracts of mammals, including humans. Some studies with B. animalis subspecies B. lactis, also known as B. lactis, (or mixtures including it) noted significant decreases in total and LDL (bad) cholesterol levels. B. lactis may also improve constipation.
The common strain B. animalis subsp. lactis HN019 was initially isolated from yogurt for supplement use and has mainly been studied for benefits to the digestive system. This strain has been found to support the intestinal barrier, reduce GI pathogens, and reduce the incidence of infectious diarrhea. It can also increase bowel movements in patients with constipation.
2. Bifidobacterium bifidum
The species most commonly used for culturing fermented milk products, this probiotic is found in the GI tract, where it provides benefits. Supplementing infant formula with B. bifidum, along with the species Streptococcus thermophilus, has been linked with lower rates of infectious diarrhea.
Some studies found that B. bifidum may have a role in preventing colon cancer, though more research is needed.
The strain B. bifidum MIMBb75 was found to significantly reduce symptoms of IBS in a clinical trial.
3. Bifidobacterium longum
One of the most common species of Bifidobacteria used for culturing fermented milk products, this species is found in the human gut. Along with B. breve, it produces vitamins, including vitamin C and vitamins B1, B6, and B12. It may also help strengthen the intestinal barrier and protect against infection.
B. longum subsp. infantis, also known as B. infantis, has been found in some studies to improve symptoms of IBS. It’s also an important colonizer of the newborn gut microbiome.
In one study, the B. infantis strain EVC001 was found to reduce pathogenic bacteria and intestinal inflammation in breastfed infants.
4. Lactobacillus acidophilus
This well-known probiotic has been researched for many decades for its health benefits and is commonly used in fermented milk products. It’s found in the human GI tract, mouth, and vagina.
L. acidophilus strains have shown effectiveness against bacterial infections in the vagina. L. acidophilus has also suppressed the growth of colon cancer in lab studies, but more research is needed. Some studies have shown that L. acidophilus or multi-strain products containing it reduced total and LDL cholesterol levels.
L. acidophilus NCFM is a common strain. It’s been linked with a reduction in bloating in individuals with IBS.
5. Lactobacillus casei
Found in the human mouth, vagina, and GI tract, this probiotic is also used for fermenting foods. Some research indicates that this species reduces the risk of antibiotic-associated diarrhea and acute infectious diarrhea. It has also suppressed the growth of colon cancer in some studies, but more research is needed.
The strain L. casei DN-11401 was found to significantly reduce the incidence of antibiotic-associated diarrhea.
6. Lactobacillus paracasei
The closely related L. paracasei species has also been used in fermented food production. Along with L. rhamnosus, this species was linked with a lower incidence of eczema in children.
The strain L. paracasei subspecies paracasei F19 lessened bloating in patients being treated for diverticular disease.
7. Lactobacillus plantarum
This probiotic colonizes the human mouth, GI tract, and vagina. It’s also found in a wide variety of fermented foods. L. plantarum has been found in some studies to reduce levels of total and LDL cholesterol.
The well-researched strain L. plantarum 299v has been shown to decrease IBS symptoms. It’s also been found to increase iron absorption and may prevent iron deficiency in those at risk.
8. Lactobacillus reuteri
L. reuteri has been found in the human GI tract and urinary system, skin, and breast milk and seems to have a variety of health benefits. It has known antibacterial effects, and some strains have been found to protect against vaginal candida infections.
L. reuteri has also been found to help with a variety of digestive health conditions, including acute diarrhea and improvement in symptoms of infant colic and IBS, and it may lower cholesterol.
The strain L. reuteri RC-14 has been found to block the candida species involved in vaginal yeast infections.
The strain L. reuteri DSM 17938 was found to reduce the duration of infectious diarrhea.
The strain L. reuteri NCIMB 30242 was found in one study to reduce levels of total and LDL cholesterol in adults with elevated levels. This strain was also shown to increase vitamin D levels. Researchers have suggested that gut microbiome changes may alter vitamin D status.
9. Lactobacillus rhamnosus
This probiotic species is closely related to both L. casei and L. paracasei and is also used to ferment dairy products. This well-studied probiotic is found in the GI tract and the vagina.
It seems to have a wide variety of actions. Its strains have demonstrated both antifungal and antibacterial action in the vagina and have been shown in some studies to reduce the risk of antibiotic-associated and acute infectious diarrhea.
This species has also been linked to a lower incidence of eczema in children. Supplementation of a strain of L. rhamnosus was found in one study to result in significant weight loss in women (but not men) with obesity.
L. rhamnosus GG, one of the most widely used probiotic strains, can fight GI pathogens and candida and has been shown to prevent diarrhea from various causes. The strain L. rhamnosus GR-1 has been found to block the candida species implicated in vaginal infections.
10. Saccharomyces boulardii
Saccharomyces boulardii has anti-pathogenic effects and has been found to reduce the risk of acute diarrhea, including antibiotic-associated diarrhea, in children and adults and to fight H. Pylori infections. It may also alleviate symptoms of IBS. It’s resistant to most antibiotics.
Specifically, the strain Saccharomyces boulardii CNCM I-745 has been shown to prevent gastroenteritis and antibiotic-associated diarrhea.
The Power of Multi-Strain Formulations
Different strains of bacteria perform different functions in the body. Even more interesting, studies have shown that probiotic strains work in teams to enhance each other’s functions. Sometimes, these teams can even perform functions together that each strain cannot accomplish alone.
Think about a sports team: For a winning team, you carefully balance your offense and defense and assign players to different positions and roles. You would not think to choose just offense or just defense players for your whole team because the team’s performance would suffer.
It’s the same with probiotics. Instead of taking a probiotic that contains a very high CFU count of one probiotic strain, in many cases, it is more beneficial to supply your gut flora with a variety of strains and species to help restore and maintain optimal balance.
This is why each Omni-Biotic formulation is a multi-strain, multispecies formulation. The probiotic strains are mindfully combined with specific health outcomes in mind. As such, Omni-Biotic Stress Release contains nine probiotic strains that help support the gut flora and the gut-brain axis during times of stress. Some strains in this formulation help manage inflammation in the intestines, whereas other strains support a strong gut barrier, while even other strains support cognitive function and mood.
Where to Get Probiotics
Probiotic foods include yogurt, kefir, kimchi, natto, miso, sauerkraut, and kombucha. Most of these contain Lactobacillus or Bifidobacterium, or possibly Bacillus species. However, some of these foods may not contain enough probiotic bacteria to survive passage through the GI tract. To provide probiotic benefits, foods should have 106 colony-forming units (CFU) per gram of viable live bacteria. However, food manufacturers often don’t provide this information.
It may be preferable to choose a targeted probiotic supplement with known levels of probiotics. You can choose probiotic species and strains based on demonstrated health benefits. Many probiotic products contain multiple strains.
In addition to the genus, species, and strain of probiotics, product labels should list the number of CFU, the recommended dose, and storage instructions. Probiotic supplements should have 107 to 1011 CFU/g of viable active microorganisms, and CFU should be listed for the end of the product’s shelf life.
Many studies demonstrating the various health benefits of probiotics have used multi-strain products. Studies on the prevention of antibiotic-associated diarrhea and diarrhea caused by C. difficile have mainly used multi-strain products, as have those with positive effects on symptoms of IBS and ulcerative colitis.
One review on lipid levels found significant decreases in total and LDL cholesterol levels only in the studies using probiotics with multiple strains.
Probiotics with multiple Lactobacillus and Bifidobacterium species given for twelve weeks significantly improved measures of insulin resistance and also lowered the waist-to-hip ratio in subjects with type 2 diabetes. Multi-strain probiotics have also shown benefits in the blood glucose and lipid levels of patients with gestational diabetes.
Be sure to check in with your healthcare provider about any chronic health conditions before starting new dietary supplements, including probiotics.
To find a multi-strain product that meets your needs, try out our quick product fit quiz.