Guide to the Best Probiotics for Gut Health: Strains that Are Backed by Science.

What Are the Best Types of Probiotics?

Taking probiotic supplements with the right types of probiotics (i.e. probiotic strains) in proper doses may provide numerous health benefits. However, many of the gut health supplements you find on the market miss the mark in terms of potency and probiotic strain selection.

So, what are "probiotic strains" exactly? Which probiotics are best to take according to research?

This article will provide overviews of some of the most rigorously studied types of probiotics and their associated health benefits. We'll also show you how to find probiotic supplements with these different strains of bacteria and fungi so you can restore and maintain a healthy balance of gut microflora.

How Do Probiotics Work?

When you take probiotics, live bacteria/microbes are delivered to your gut lumen so they can colonize the intestinal epithelium. As humans, we share a symbiotic relationship with the good microbes in our gut; they can benefit us by producing short-chain fatty acids, digesting nutrients, and neutralizing pathogens; we can help them by consuming prebiotics like Transparent Labs Prebiotic Greens.

The balance between good and bad bacteria/microbes in the gut influences many biological and metabolic processes, even energy balance, hormonal rhythms, mental performance, and immune function. Studies have shown that those with a greater proportion of "unfriendly" gut microbes may have a more challenging time losing weight, overcoming infections/illness, and controlling inflammation [1].

To understand why the different types of probiotics in a dietary supplement matter, it's necessary to have a rudimentary grasp of what constitutes the human gut microbiome.

Microbes in the gastrointestinal (GI) tract of humans, particularly the small intestine, are collectively referred to as the human gut microbiome. Microbiologists postulate there are ten times as many microbial cells living on and within the human body than human cells [2]. Gut bacteria account for a weighty proportion of these microbes.

Over 99% of the microbes living in the gastrointestinal tract are bacteria, and estimates suggest that these microbes comprise upwards of 1,000 different species. Some are beneficial bacteria, while others are harmful bacteria. 

The remaining <1% of microbes in the gut are fungal species, notably yeast from the Candida genus. Note that probiotic yeast, such as Saccharomyces boulardii, can benefit the gut just like certain types of bacteria [3]. However, yeast are types of fungus, not bacteria.

Research in recent years has found significant variations in gut microbiota composition from humans of different geographical regions, ethnic backgrounds, and age groups [4]. But the most impactful factors on the gut microbiome are lifestyle choices like nutrition habits, activity level, sleep, and taking probiotics [5]. 

So, what can we do to overcome the challenges of an imbalanced gut microbiome? Well, eating a proper diet and regular exercise are prudent. Using probiotics and prebiotics can also help by restoring and sustaining a healthy balance of gut microbiota.

The catch with probiotic supplements is that they often contain diverse bacteria strains, some of which may not be as beneficial as the claims suggest. But the more concerning issue is that consumers don't really understand which specific strains of good bacteria to look for in a probiotic supplement.

If you're confused about what probiotic strains are and why they make a big difference when taking probiotics, the following sections will get you up to speed.

What Are Different Strains of Probiotics (Probiotic Types)?

A probiotic strain, or probiotic type, is a subtype (think: viral variants) of a beneficial microbial species. Most species used as probiotics belong to the Lactobacillus and Bifidobacterium genera [6]. Bacillus and Streptococcus are also garnering interest as genera for identifying probiotics. And as noted earlier, some yeast species, like Saccharomyces boulardii and Issatchenkia occidentalis, are viable fungal probiotics [7].

Common types of probiotics from the Lactobacilli genus include:

• Lactobacillus acidophilus (the Latin term "acidophilus" means "acid-loving")
• Lactobacillus reuteri
• Lactobacillus casei
• Lactobacillus gasseri
• Lactobacillus fermentum
• Lactobacillus plantarum
• Lactobacillus rhamnosus

These bacterial species are often used as starter cultures for fermented foods, especially dairy products like Greek yogurt. Hence, consuming yogurt made from live bacterial cultures is one way to get the benefits of Lactobacilli probiotics.

Other bacterial strains used in probiotic supplements often belong to the genus Bifidobacterium, notably:

• Bifidobacterium infantis
• Bifidobacterium longum
• Bifidobacterium lactis
• Bifidobacterium breve

Certain Bifidobacterium strains from these species have been shown to bolster the immune system, reduce LDL ("bad") cholesterol, and alleviate symptoms of irritable bowel syndrome (IBS) [8].

But here's where things get a bit tricky with probiotic supplements. Many species of good bacteria/microbes have one or more subtypes with distinct health benefits, or lack thereof.

What's disconcerting is that most probiotic supplements don't list any specific strain next to the microbial species on the label. Taking probiotics that don't explicitly state any particular strains of microbes is like playing a guessing game. And odds are, it's not doing much good for your general health.

If you currently take probiotics that suffer from the same flaw, it's time to switch things up. Here are some of the best probiotics to look for in dietary supplements:

Lc-11™ (Lactobacillus casei strain ATCC SD5213)

• Identified as Lactobacillus casei strain ATCC SD5213 and was initially isolated from a dairy source
• Lc-11™ is a registered trademark of DuPont Danisco
• Used globally since the early 2000s as an ingredient in food and nutritional supplements, with no reported consumer illness or injury
• Tested in several clinical studies (as of 2021), primarily involving adults, and has a long history of safe use in humans

Lc-11™ is highly resistant to acidic environments and readily withstands bile found in the GI tract of humans. This particular strain of Lactobacillus casei is found naturally throughout the human intestinal tract and is also used for making many fermented foods. It is also found on the Qualified Presumption of Safety (QPS) list in Europe.

Clinical research has shown that Lc-11™ may protect against cancer in the lower gastrointestinal tract by adhering to Caco-2 cell lines [9]. Other findings suggest that Lc-11™ acts as a natural antibiotic and pathogen inhibitor by secreting inhibitory compounds, competing for adhesion sites, blocking the action of bacterial toxins, and stimulating immunoglobulin A [10]. Lc-11™ is also resistant to most antibiotic prescription drugs.

Bb-03™ (Bifidobacterium breve strain ATCC SD5206)

• Identified as Bifidobacterium breve strain ATCC SD5206 (unknown original origin)
• Bb-03™ is a registered trademark of DuPont Danisco
• Used as an ingredient in food and nutritional supplements, with no reported consumer illness or injury 
• Only a select few studies have been done on Bb-03™ as of 2018, but the Bifidobacterium species as a whole has been heavily researched and is safe for human consumption

Bb-03™ is tolerant to acidic (low pH) conditions and readily resists bile found in the GI tract of humans. It is also found on the Qualified Presumption of Safety (QPS) list in Europe, and there appears to be no acquired antibiotic resistance for it.  

Similar to Lc-11™, research suggests that Bb-03™ might be a potent pathogen inhibitor and anti-cancer probiotic [11]. Studies have also found that Bb-03™ is beneficial for immune system development in young children [12].

Bifidobacterium BB-12® (Bifidobacterium lactis strain DSM 15954)

• Identified as Bifidobacterium lactis strain DSM 15954 and derived from Chr. Hansen’s bacterial culture collection
• Bifidobacterium BB-12® is a registered patent of Chr. Hansen A/S
• Used worldwide since 1985 as an ingredient in food and nutritional supplements, with no reported consumer illness or injury
• Over 180 clinical studies as of 2016 with no reported serious side effects or adverse events (even in doses of more than 100 billion CFU per day)

Bifidobacterium lactis BB-12® has received Generally Recognized As Safe (GRAS) status by the United States Food and Drug Administration (FDA). It is a highly studied and clinically renowned probiotic strain, particularly for treating irritable bowel syndrome (IBS) and constipation.

A multi-national study encompassing over 1,200 European participants demonstrated that even a minimal BB-12® dose (1 billion CFU per day) increased weekly bowel movement frequency by nearly 200% in constipated individuals [13]. 

BB-12® has also been shown to have strong immunomodulating benefits; in a controlled 6-week clinical trial of 211 subjects, those taking BB-12® had a 65% greater increase of plasma immunoglobulins than the placebo group [14].  

Other potential evidence-based benefits of BB-12® may include:

• Reduce the risk of an upset stomach and antibiotic-associated diarrhea [15]
• Reduce the risk of H. pylori infection [16]
• Support healthy metabolism of carbohydrates and dietary fats [17]
• Attenuate symptoms of skin irritation [18]
• Help fight upper respiratory tract infections [19]

Bl-05™ (Bifidobacterium longum strain ATCC SD5206)

• Identified as Bifidobacterium longum strain ATCC SD5206 (unknown origin source)
• Bl-05™ is a registered trademark of DuPont Danisco
• Used primarily in food products as a culture starter and fermenting agent
• Limited human data exists on this strain, but preliminary evidence is promising, and it’s considered safe for consumption

Bl-05™ is still under investigation in terms of its potential benefits in humans. Nevertheless, Bl-05™ is tolerant of low pH conditions and survives in the presence of bile. It has several studies documenting its safety for use and is also on the Qualified Presumption of Safety (QPS) list in Europe [20].

Preliminary findings are encouraging for this strain of Bifidobacterium longum. Bl-05™ may inhibit pathogens and protect the GI tract by interacting with the intestinal mucosa and modulating the immune system [21].

A noteworthy two-week murine study found that daily feeding probiotic cheese fortified with Bl-05™ resulted in more than a 100% increase in HDL ("good") cholesterol and a 50% decrease in total blood triglycerides [22]. Therefore, Bl-05™ may favorably alter biomarkers associated with cardiovascular function. 

Bl-04™ (Bifidobacterium lactis strain ATCC SD5219)

• Identified as Bifidobacterium lactis strain ATCC SD5219 and is of human origin
• Bl-04™ is a registered trademark of Dupont Danisco
• Used worldwide since the mid-2000s as an ingredient in food and nutritional supplements, with no reported consumer illness or injury
• Over 20 clinical studies and peer-reviewed studies as of 2018 with no reported serious side effects or adverse events
• Often studied in conjunction with L. acidophilus probiotics

Bl-04™ is ostensibly one of the most beneficial probiotic strains reducing the risk of infection and increasing immunity. A sizeable and lengthy double-blind, placebo-controlled study investigated the effect of various probiotics on the risk of colds and respiratory infections in healthy, active adults [23]. The subjects were divided into three groups:

• Group 1 was given BI-04™ alone
• Group 2 was given a combination of Lactobacillus acidophilus NCFM® & Bifidobacterium lactis Bi-07
• Group 3 was given a placebo

After the 5-month trial period, the group receiving Bl-04™ had the highest reduction in infection risk (27%) compared to placebo, whereas group 2 had a 19% reduction.

Another health benefit of Bl-04™ is that it can help balance gut flora after antibiotic therapy [24].

La-14™ (Lactobacillus acidophilus strain ATCC SD5212)

• Identified as Lactobacillus acidophilus strain ATCC SD5212 and of human origin
• La-14™ is a registered trademark of DuPont Danisco
• Used worldwide since the 1990s as an ingredient in fermented foods (particularly kefir) and nutritional supplements, with no reported consumer illnesses or injury
• Over 25 clinical studies as of 2021; very well-tolerated even in substantial doses

La-14™ is highly resistant to acidic conditions and bile found in the GI tract of humans. This particular strain of Lactobacillus acidophilus naturally occurs throughout the intestinal tract and is also used for making fermented food products. It is also found on the Qualified Presumption of Safety (QPS) list in Europe. 

Clinical research thus far has shown that La-14™ may protect against pathogens by secreting compounds known as bacteriocins [25]. Other findings suggest that La-14 can reduce allergic rhinitis (again, by secreting certain bacteriocins) [26]. It's also a revered immune enhancer and may help treat lactose intolerance [27].

Lactobacillus GG® (Lactobacillus rhamnosus strain ATCC 53103)

• Identified as Lactobacillus rhamnosus strain ATCC 53103 and isolated from human gastrointestinal microbiota
• LGG® is a registered patent of Chr. Hansen A/S (named after the professors who discovered it)
• Used worldwide since 1990 as an ingredient in food and nutritional supplements, with no documented illnesses or adverse reactions
• Clinically studied in over 300 trials (as of 2021) in people of all ages; no reported serious side effects or adverse events (even in doses of more than 100 billion CFUs per day)

LGG® is undoubtedly the most-established probiotic strain; it has been featured in over 1000 scientific studies and 300 clinical publications as of 2021. Not surprisingly, this strain of Lactobacillus rhamnosus has received Generally Recognized As Safe (GRAS) status by the U.S. Food and Drug Administration (FDA).

Taking probiotics with LGG® may provide a multitude of health benefits. In particular, this strain has been shown to relieve diarrhea, skin irritation, irritable bowel syndrome (IBS), seasonal and food allergies, and ulcerative colitis [28, 29, 30, 31]. For example, in a trial of 81 hospitalized children, those given an LGG® probiotic supplement had a 13% reduction of rotavirus gastroenteritis and a 33% reduction of diarrheal incidence compared to the placebo group [32].

Lp-115™ (Lactobacillus plantarum strain ATCC SD5209)

• Identified as Lactobacillus plantarum strain ATCC SD5209 and was originally isolated from plant material
• Lp-115™ is a registered trademark of DuPont Danisco
• Used worldwide since the late 2000s as an ingredient in nutritional supplements, with no reported consumer illness or injury
• A select few human clinical studies as of 2018 with no reported serious side effects or adverse events 

Human clinical data suggests that Lp-115™ enhances the adaptive immune response by stimulating antigen-specific antibody production nearly twice as much as a placebo [33]. In vitro research has shown that this strain of Lactobacillus plantarum may also balance immune response by increasing interleukin-10 and interleukin-12 activity [34].

Ls-33™ (Lactobacillus salivarius strain ATCC SD5208)

• Identified as Lactobacillus salivarius strain ATCC SD5208 and derived from human gut microbiota and urogenital surfaces
• Ls-33™ is a registered trademark of DuPont Danisco
• Used worldwide since the early 2000s as an ingredient in nutritional supplements; no reported consumer illness or injury
• Limited studies on Ls-33™® have been performed as of 2021, with no reported serious side effects or adverse events

In vitro and animal studies suggest that Ls-33™ is a potent anti-inflammatory probiotic strain that works primarily by increasing interleukin-10 activity [35]. This strain of Lactobacillus salivarius may also protect against common foodborne pathogens, like Escherichia coli and Salmonella, by competing for binding sites and secreting inhibitory compounds called bacteriocins [36].

ME-3® (Lactobacillus fermentum strain DSM 14241)

• Identified as Lactobacillus fermentum strain DSM 14241 and originally isolated from a healthy one-year-old child in Estonia
• ME-3® is a registered patent of VF Bioscience
• Used since 1995 as an ingredient in dietary supplements; no documented illness or adverse reactions
• Clinically studied for over 25 years in adults and children; it has an exceptional safety and efficacy profile across age groups

ME-3® is a probiotic strain of Lactobacillus fermentum that displays excellent probiotic properties due to its resistance to bile acids and low pH environments and a lectin profile that enables adhesion to gut epithelial cells. It has maintained Qualified Presumption of Safety (QPS) status since 2007 through the European Food Safety Authority (EFSA) due to a robust body of promising clinical trials and lengthy history of supplemental use.

Interestingly, ME-3® is one of few bacterial strains that contain a complete enzymatic system enabling synthesis, uptake, and redox regeneration of reduced glutathione — one of the primary endogenous free radical scavengers and antioxidants. Glutathione also contributes to maintaining other antioxidants, like CoQ10 and vitamin E, in their active forms. Supplementing with ME-3® increases the ratio of reduced-to-oxidized glutathione in the body, thereby bolstering antioxidant status [37]. 

Other clinically significant findings suggest probiotics with ME-3® may help reduce the risk of microbial infection, enhance gastrointestinal function, and improve cardiovascular biomarkers [38, 39]

RC-14® and GR-1® (Lactobacillus reuteri and Lactobacillus rhamnosus strains ATCC 55845 and 55826, respectively)

• Identified as Lactobacillus reuteri strain ATCC 55845 and isolated from the urethra of healthy females
• RC-14® is a registered patent of Chr. Hansen A/S
• It has been used since 2004 as an ingredient in dietary supplements; no documented illnesses or adverse reactions
• Roughly 50 clinical trials in females have been conducted for these probiotics as of 2021; no reported serious side effects or adverse events

RC-14® and GR-1® are used in tandem for women’s health. These probiotics have received Generally Recognized As Safe (GRAS) status by the U.S. FDA and are backed by numerous clinical trials. Research demonstrates that combo therapy with 1 billion CFU each of RC-14® and GR-1® may benefit women by reducing the risk of urinary tract infections, bacterial vaginosis, and vaginal candidiasis [40, 41, 42, 43].

GanedenBC30® (Bacillus coagulans strain GBI-30, 6086)

• Identified as Bacillus coagulans strain GBI-30, 6086
• GanedenBC30® is a registered patent of Ganeden Biotech, Inc.
• Used around the world since 2012 as an additive ingredient in food and nutritional supplements, with no safety concerns reported
• Over 25 peer-reviewed studies as of 2021 with no adverse events or side effects (even at exceptionally high doses)
• It can be baked, boiled, frozen, etc. without any detriment to its biological viability
• It appears especially beneficial for immune health and digestive function; it may also enhance muscle recovery after intense exercise

GanedenBC30® is a highly stable, non-GMO patented strain of Bacillus coagulans (known as GBI-30, 6086) that has received Generally Recognized As Safe (GRAS) status from the United States Food and Drug Administration (FDA). This particular probiotic strain is exceptionally stable due to the cell’s protective spore-forming ability, which allows it to withstand harsh digestive and manufacturing environments. 

GanedenBC30® is one of the newest patented probiotics to hit the market, and the current research is quite promising. Findings suggest that this probiotic strain has strong immunomodulatory and anti-inflammatory properties, working to support adaptive immunity (primarily by increasing CD4 T-lymphocyte levels) [44].

Further evidence suggests GanedenBC30® can improve abdominal pain and bloating symptoms in patients with irritable bowel syndrome (IBS), but more extensive trials are needed to confirm this benefit [45].

One of the most compelling studies behind GanedenBC30® measured total recovery time and muscle soreness in healthy adults after max-effort intervals on an indoor cycle. The results showed that subjects who received a casein protein supplement in conjunction with GanedenBC30® experienced significantly less perceived soreness than those who received only casein protein [46]. Creatine kinase levels were also about 50% lower in subjects who received protein + GanedenBC30®.

LactoSpore® (Bacillus coagulans strain MTCC 5856)

• Identified as Bacillus coagulans strain MTCC 5856
• Lactospore® is a registered patent of Sabinsa Corporation
• Used worldwide since 1998 as an ingredient in food and food supplements, with no reported consumer illnesses or injury
• Tested in several clinical studies of adults; no documented significant side effects or adverse events

LactoSpore® is a patented strain of Bacillus coagulans (known as MTCC 5856) that has received Generally Recognized As Safe (GRAS) status from the United States Food and Drug Administration (FDA). This strain can withstand even the most acidic conditions within the human stomach. 

LactoSpore® is so-named because it forms spores. When activated by the stomach's acidic environment, spores can germinate and multiply in the intestines, producing the favorable L(+) form of lactic acid and effectively inhibiting the growth of pathogens. 

Research shows that Bacillus coagulans MTCC 5856 effectively establishes a healthy gut microbiome, especially in those who suffer from irritable bowel syndrome (IBS). A pilot clinical trial in subjects with highly debilitating IBS showed that LactoSpore® supplementation improved quality of life scores by 20% and reduced the frequency of bloating symptoms by an astounding 30-fold compared to placebo treatment [47].

A separate clinical trial of adults undergoing a 21-day weight loss program found that LactoSpore® significantly improved fat loss and blood lipid profiles compared to those taking a placebo [48] (albeit the subjects used many other supplements in this study).

Which Probiotics Are Best?

The best probiotic supplements aren't necessarily the ones formulated with 30+ strains of bacteria. While there are hundreds of probiotic types, the strains discussed above are among the most beneficial bacteria.

Remember that taking a specific strain of good bacteria won't confer the desirable health benefits if you don't take a sufficient dose (CFUs). The live bacteria in probiotic supplements need to survive the stomach's acidic environment to colonize the intestines. As such, adequate doses may be upwards of 20 billion CFUs for a single strain of probiotic bacteria.

Lastly, avoid probiotic supplements that contain proprietary blends of probiotics and prebiotics. There is an unceasing trend of these types of probiotics cropping up on Amazon, and their too-good-to-be-true price point reflects that.

The issue with taking probiotics that have proprietary blends is that they don't tell you the dose of the specific strains of beneficial bacteria. In other words, you're most likely not getting effective amounts of live bacteria or the right types.

To celebrate the launch of Transparent Labs Gut Health, a high-quality probiotic formula delivering 100 billion colony-forming units (CFUs) of 10 different types of probiotics that have been clinically studied, including:

• Lactobacillus acidophilus (LA-14)
• Lactobacillus rhamnosus (LR-32)
• Lactobacillus casei (LC-11)
• Lactobacillus plantarum (LLP-115)
• Lactobacillus paracasei (LPC-37)
• Bifidobacterium lactis (BL-04)
• Lactobacillus salivarius (LS-33)
• Streptococcus Thermophilus (ST-21)
• Bifidobacterium bifidum (BB-02)
• Bifidobacterium breve (BB-03)

These probiotic strains have been shown to provide a range of health benefits, including:

• Supporting a healthy immune system
• Alleviating symptoms of irritable bowel syndrome (IBS)
• Enhancing nutrient breakdown and digestion
• Promoting cognitive function
• Encouraging healthy body composition
• Restoring beneficial gut bacteria after the use of antibiotics

TL Gut Health has been in the works for quite some time, and the wait was well worth it. If you're searching for one of the best probiotic supplements on the market, trust your gut (no pun intended) and grab a bottle today by clicking here.