Probiotics are a dietary supplement growing in popularity and gaining shelf space in pharmacies and grocery stores. Yogurt companies call out the probiotic contents in their containers and big manufacturers get into the game. That’s because the growing body of research around the health benefits of probiotics and the importance of biodiversity in the gut microbiome is ever-mounting.
Biodiversity is the variety of life forms within an ecosystem. In virtually all ecosystems across the planet, biodiversity creates thriving communities of microorganisms, plants, animals, and fungi. The interplay between organisms allows for thriving rain forests, oceans, deserts, etc. And this is also true within your gastrointestinal system. Your gut health relies upon a diversity of species living therein, each offering symbiotic and beneficial effects for you, the host.
So, it would logically follow that taking a probiotic supplement that offers a diversity of microbes would support a healthy gut, right?
While more research needs to be done comparing the beneficial effects of single-strain probiotics to multi-strain probiotics, large-scale research endeavors on the topic seem to show that probiotic blends may be the way to go [1 Trusted SourcePubMedGo to source, 2 Trusted SourcePubMedGo to source].
Terms: Category, Species, and Strain
Some of the terminology used in the formulation of probiotic products can get a little confusing, making it hard to find what you’re looking for. Furthermore, some terms are used interchangeably despite having different meanings, which can lead to even more confusion. For example, multi-strain probiotics and multi-species probiotics are two different things, despite the terms being used interchangeably.
Let’s do a deep dive into definitions and types of probiotics to gain a better understanding of what the research says about a diverse approach to supplementing with probiotic products.
Before we take a closer look at the research on a biodiverse approach to supporting gut health, it’s important to understand the terminology. In some cases, words like “multi-strain probiotics,” “multi-species probiotics,” and “multi-category probiotics” are mistakenly used interchangeably (almost always called “multi-strain probiotics”). We’ll untangle these terms and then share some insights about each.
The vast majority of probiotics fall into three recognized categories:
Lactobacillus bacteria and Bifidobacterium
Saccharomyces boulardii (a type of beneficial fungus)
The first category contains thousands of species of beneficial bacteria within the two genera: Lactobacillus (Lacto for short) and Bifidobacterium (Bifido for short). This is the most widely available type of probiotic you’ll find on your health food or supplement store shelves. The second is a single species of fungus, from which many different strains have been developed and studied.
The third, soil-based probiotics, might be the most controversial of the three due to the spore-producing behavior of the bacteria in question (Bacillus bacteria). Some believe that these bacteria could be invasive. While there are some harmful soil-based bugs, many known species have proven safe in clinical trials [3 Trusted SourcePubMedGo to source].
Probiotic Species vs. Strains
You may have noticed that the labels on many probiotic supplements list ingredients in the billions CFU (colony-forming units). They also have long Latin names you’ve probably never seen before, sometimes followed by a series of numbers and letters. Those names are the names of the individual species of probiotics, and the numbers and letters that come after indicate specific strains.
As an example, Lactobacillus acidophilus is a bacterial species of probiotic. You might see just those two words on a probiotic label, but you might also see Lactobacillus acidophilus ATCC 832, Lactobacillus acidophilus LMG 11428, or some other set of letters and numbers. Those letters and numbers represent different bacterial strains of lactobacillus acidophilus. Strains are usually proprietary, developed by a company or private entity, and patented.
Think of species vs strain the way you might think about dog breeds. Dogs are all the same species, Canis familiaris. They can mate with each other and produce fertile offspring. But each breed of dog is quite different from the next. You’d never breed a dachshund with a cattle dog, and each of those breeds has specific traits that make them great at the jobs they were bred to do (ratting and herding, respectively).
While the scientific community doesn’t have enough information about the vast potential of breeding particular strains of microflora for particular purposes, it’s true that strain-specific clinical studies are done to examine their effects on human conditions like abdominal pain, yeast infections, depression, irritable bowel syndrome (IBS), constipation, diarrhea, bloating, and more. We’ll get into more detail on that in a minute. For now, it’s important to realize that the words multi-strain probiotics and multi-species probiotics don’t mean the same thing, but are used interchangeably by many.
Single-Strain Probiotics vs. Multi-Species/Multi-Strain Probiotics
As we mentioned earlier, the research is mixed regarding whether multi-species/multi-strain probiotic supplements are more effective than single-strain/species. A number of rigorous meta-analyses and systematic reviews of placebo-controlled studies seem to show both types of results: Multi-strain seems more effective at addressing conditions like gut imbalance, immune health, depression, high cholesterol, etc. And, single-strain probiotics can be just as effective as multi-strain probiotics for those conditions or diseases.
In one meta-analysis of 38 randomized controlled trials, researchers concluded that a mix of bacterial species were more effective than single-species probiotics for the treatment of inflammatory bowel disease (IBD) [4 Trusted SourcePubMedGo to source, 5 Trusted SourcePubMedGo to source].
On the other hand, a literature review of studies spanning from 1973 to 2019 looking at the efficacy of single-strain or multi-strain probiotics did not find a significant difference in efficacy between the two across eight different diseases [6 Trusted SourcePubMedGo to source].
That being said, when biodiversity in gut flora is the goal for optimal digestive health, it’s easy to lean toward supplementing a range of probiotic bacteria to achieve that goal. With multiple types of beneficial bacteria working together to outcompete the potentially harmful bugs, you have a better chance of overcoming a potential health threat and benefiting your overall wellness with diverse microbiota. However, more comparative work needs to be done to better understand the potential synergy that may exist when combining various species and strains of probiotics.
Understanding the Research on Different Probiotic Strains
Context is key when it comes to understanding research results. In the case of probiotics, many probiotic makers will test their own proprietary strains in the treatment of particular ailments in order to ascertain their effects.
Here’s what gets lost in translation if you don’t have context: the lack of evidence that any one strain of a probiotic species is more effective than another at treating anything. In other words, just because a single strain is studied for a particular use doesn’t mean that another strain (or species) of bacteria or fungus is less effective for that particular use. It’s just a matter of what’s been studied and the results of those studies [7 Trusted SourcePubMedGo to source].
Triple Therapy: Multi-Category Probiotics
The multi-category approach to using probiotics is a different approach that’s worth looking at, despite a lack of controlled trials on the topic. The three categories of probiotics (Lacto/Bifido, Saccharomyces, and soil-based) each contain many species and strains that offer their own unique benefits. A triple-therapy approach takes one or some from each of the three categories and combines them.
I’ve found that patients in my clinic have significantly benefited from this approach after they didn’t achieve their desired outcomes from a single-category probiotic product.
When tackling a health goal, whether it’s boosting your immune system or digestive system, improving metabolic function, rehabbing an injury, alleviating anxiety or depression, getting stronger at the gym, or addressing a problem like SIBO or IBS, the best course of action is to hit the problem from all angles. For the sake of simplicity, let’s look at rehabbing a knee injury.
If you’ve tweaked your knee and have been nursing your injury for a while, chances are you’ve been overcompensating on the other leg, allowing the injured leg to lose some strength and stability. The goal then would be to restore strength and stability for that knee and the surrounding muscles.
Potential strategies to do that are multi-faceted. You’ll want to reduce the inflammation, strengthen through exercises that use your knee from every direction, and stretch the muscles around your knee so that they’re all getting stronger and more flexible as you rehab.
Now imagine going to a personal trainer who tells you that all you need to do is one type of stretch for that injury. Do you think that would work to get your knee back in action? Or would you get a second opinion?
The triple-therapy approach to probiotic supplementation is a holistic approach to addressing your health concerns, just like stretching, strengthening, and reducing inflammation would be for a knee injury. With a product that contains beneficial flora from each of the three categories, you can address your gut health from all angles.
The Bottom Line
When it comes to choosing which probiotics are right for you, the terminology of different strains, species, and categories is less important than just turning the bottle over and looking at the ingredients.
The most commonly available probiotics on the market are multi-species and single-species probiotics from the first category (lacto- and bifido). But that doesn’t mean you can’t find the other two. They just might not all be in the same bottle. Mix up your probiotics in order to give your microbiota a chance to diversify using the triple therapy approach.
If you start with the first category, look for a probiotic that has multiple species of lacto- and bifido-bacteria listed on the label in the billions. For all probiotic supplements (and supplements in general, since they aren’t regulated by the Food and Drug Administration), make sure you’re purchasing from a reputable company and that the bottle has a valid manufacturing or expiration date. This will help you to avoid purchasing dead probiotics.
Zhang C, Jiang J, Tian F, Zhao J, Zhang H, Zhai Q, et al. Meta-analysis of randomized controlled trials of the effects of probiotics on functional constipation in adults. Clin Nutr. 2020 Oct;39(10):2960–9. DOI: 10.1016/j.clnu.2020.01.005. PMID: 32005532. Trusted SourcePubMedGo to source
Lefevre M, Racedo SM, Denayrolles M, Ripert G, Desfougères T, Lobach AR, et al. Safety assessment of Bacillus subtilis CU1 for use as a probiotic in humans. Regul Toxicol Pharmacol. 2017 Feb;83:54–65. DOI: 10.1016/j.yrtph.2016.11.010. PMID: 27825987. Trusted SourcePubMedGo to source
Zhang X-F, Guan X-X, Tang Y-J, Sun J-F, Wang X-K, Wang W-D, et al. Clinical effects and gut microbiota changes of using probiotics, prebiotics or synbiotics in inflammatory bowel disease: a systematic review and meta-analysis. Eur J Nutr. 2021 Aug;60(5):2855–75. DOI: 10.1007/s00394-021-02503-5. PMID: 33555375. Trusted SourcePubMedGo to source
Sun J, Buys N. Effects of probiotics consumption on lowering lipids and CVD risk factors: a systematic review and meta-analysis of randomized controlled trials. Ann Med. 2015 Sep 4;47(6):430–40. DOI: 10.3109/07853890.2015.1071872. PMID: 26340330. Trusted SourcePubMedGo to source
McFarland LV. Efficacy of Single-Strain Probiotics Versus Multi-Strain Mixtures: Systematic Review of Strain and Disease Specificity. Dig Dis Sci. 2021 Mar;66(3):694–704. DOI: 10.1007/s10620-020-06244-z. PMID: 32274669. Trusted SourcePubMedGo to source
Ouwehand AC, Invernici MM, Furlaneto FAC, Messora MR. Effectiveness of Multistrain Versus Single-strain Probiotics: Current Status and Recommendations for the Future. J Clin Gastroenterol. 2018;52 Suppl 1, Proceedings from the 9th Probiotics, Prebiotics and New Foods, Nutraceuticals and Botanicals for Nutrition&Human and Microbiota Health Meeting, held in Rome, Italy from September 10 to 12, 2017:S35–40. DOI: 10.1097/MCG.0000000000001052. PMID: 29734210. Trusted SourcePubMedGo to source
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