When you hear the word "probiotics" you probably think of gut health. And for good reason.
In addition to filling our fridges with probiotic foods like yogurt and kombucha, probiotics have quickly become one of the most popular supplements in the United States.
In fact, the 2012 National Health Interview Survey showed that about 4 million people take them to support everything from healthy digestion to bloat and immune function.* (And that number has likely spiked in the last month thanks to newfound issues like quarantine constipation and excess bean bloat.)
Despite their popularity, it's important to note that there's no one-size-fits-all approach to probiotics.
There are many different types of probiotics—called strains—and each one has its own special function.
Every person also has a unique gut microbiome—or balance of beneficial bacteria in the gut—so the best probiotic for you may be different from the ideal choice for someone else.
To get the most benefits of probiotics, you need to find the strain(s) targeted to your specific symptoms.
What are probiotics?
Probiotic supplements are living microorganisms (usually bacteria or yeast) that help maintain balance in your gut microbiome.*
Aside from supporting your gut health and alleviating uncomfortable digestive symptoms, like bloating and constipation, probiotics have also been linked to a healthier immune system, reduced cholesterol, improvements in allergy symptoms, and a lower rate of infections.*
Because probiotics are so popular, manufacturers have made the supplements readily available in all forms. You can find them as pills, capsules, and powders.
Probiotics are even frequently added to other supplements, like greens powders, to boost their nutritional value.*
How probiotic strains get their name.
All probiotics have three different qualifiers: genus, species, and strain (in that order).
For example, when looking at Bifidobacterium lactis BI-07, Bifidobacterium is the genus, lactis is the species, and BI-07 is the strain. But what does that all mean? Below, we've broken it down.
- Genus: Genus is the broadest identifier. It encompasses several different types of bacteria in the same general category but with lots of different characteristics and health benefits.
- Species: The term species gets a little more specific. All of the bacterial strains within a species have similar characteristics but with some subtle differences between them.
- Strain: A specific strain is one type of bacteria. All of the bacteria identified within a strain carry out the same function within your body.
Bifidobacteria vs. Lactobacillus: What's the difference?
Lactobacillus ferment refined sugars and create lactic acid, while bifidobacteria mainly produce short-chain fatty acids, or SCFAs, although they create lactic acid too.
Another difference is where they live and colonize (or grow). Lactobacillus naturally lives in the small intestine, while Bifidobacterium takes up residence in the large intestine (or colon).
That also means that when you take a probiotic supplement, the Lactobacillus strains travel to—and grow in—your small intestine, while the Bifidobacterium strains have a longer journey to get to your large intestine.
These different locations in your gut translate to different health benefits.
Bifidobacteria, which are gram-positive anaerobic bacteria, play a huge role in promoting normal inflammatory processes in the gut3 and helping you digest carbohydrates.
Lactobacillus—gram-positive, non-spore-forming bacteria—are arguably the most well-known probiotic even though they only account for about 0.01%10 of the total bacterial count in the gut. But while this seems like a low number, it doesn't diminish their importance.
There are about 170 different species of Lactobacillus, and the general health benefits include:
Common species and strains in probiotics.
Of course, there are many species within the Bifidobacteria and Lactobacillus genera and many different strains within those species.
Even though some bacterial strains may always remain a mystery, there are some have a long history of good research and clinical use. These include:
Lactobacillus casei BF1, BF2, and BF3: can inhibit the growth of Helicobacter pylori and Staphylococcus aureus22, two pathogenic bacteria well known for causing human infection and resulting health problems.*
Lactobacillus plantarum DSM 9843: can improve gas and flatulence in people with irritable bowel syndrome.*
Choosing a probiotic supplement.
According to Vincent M. Pedre, M.D., a board-certified internist, the bacterial strains that are actually in many commercially produced supplements don't match the claims on the bottle.
That's why it's important to get your supplements from a reputable, high-quality manufacturer.
He recommends choosing a probiotic that's targeted to what you're trying to treat, contains multiple strains, and 5 to 100 billion colony-forming units (CFUs).
It's also a good idea to make sure your probiotic is tested by a third-party lab to ensure that it contains what it says and that the bacterial strains are alive and doing their jobs.
Note that while many probiotic supplements are refrigerated to help with this, high-quality supplements can also be made shelf-stable and don't require refrigeration.
For more specific recommendations, check out one of our probiotics roundups.
The bottom line
While probiotic supplements have a long-list of health benefits, from gut support to immune function,* there are many different strains of bacteria in probiotics, each with its own special functions.
Understanding the different strains is key to finding a targeted supplement and reaping those benefits.*
Lindsay Boyers is a holistic nutritionist specializing in gut health, mood disorders, and functional nutrition. Lindsay earned a degree in food & nutrition from Framingham State University, and she holds a Certificate in Holistic Nutrition Consulting from the American College of Healthcare Sciences.
She has written twelve books and has had more than 2,000 articles published across various websites. Lindsay currently works full time as a freelance health writer. She truly believes that you can transform your life through food, proper mindset and shared experiences. That's why it's her goal to educate others, while also being open and vulnerable to create real connections with her clients and readers.