‘Gut mania’ is at an all-time high. Despite the ever-increasing number of ‘probiotic’ supplements, foods, and beverages out there, there’s still a lot of confusion about what probiotics are, how they work, and why we should take them. We’ve clarified the 7 most common myths.

1. Probiotics are only for digestion.

61% of Americans live with gastrointestinal issues. 63 million suffer from chronic constipation. So it’s unsurprising that most people exclusively associate probiotics with digestive health. But this is a common misconception.



Your body is complex and interconnected, and the gastrointestinal system sits at the core of it all. It’s connected to and influences everything from metabolic and gut immune function to cardiovascular, dermatological, and urogenital health. So, while improvements in gut health are often the most immediate, localized, and evident (with digestion often improved in as little as 24-48 hours), probiotics can actually have powerful effects across the entire body, far beyond your digestive tract.

2. Probiotics can be found in fermented foods and beverages like kombucha.

You drank a kombucha on your way to the gym, and this pack of nuts you’re munching on now says it’s probiotic. You’re good, right?



Well, scientifically speaking, many of the products out there that claim to be probiotic, don’t actually qualify as one. Just because something contains live microorganisms, doesn’t mean it satisfies the scientific definition of ‘probiotic’—”live microorganisms that, when administered in adequate amounts, confer a health benefit on the host”, a definition authored by the United Nations – World Health Organization Expert Panel chaired by our Chief Scientist, Dr. Gregor Reid, in 2001.



You might have ingested some bacteria, but do you know which strains? In what quantities? Have they survived the acidic journey through your digestive system and landed in your colon? Have those strains been studied, in those quantities, to actually do something in your body?



This is, of course, not to say that you shouldn’t eat or drink fermented foods and beverages. Many are extremely nutritious, not to mention very tasty, additions to your diet (though we do suggest keeping an eye out for excessive sugar content—as many commercial products like yogurts and beverages are sweetened with added sugars). The distinction is that they are not necessarily reliable sources of beneficial, effective bacteria.



The science of probiotics demands precision, accountability, and efficacy (you are putting live bacteria in your body, after all).

3. Probiotics don’t work unless they colonize your gut.

When it comes to taking probiotics, you may have heard that you need to ‘restore’ your gut or ‘put the good bacteria back’. This is based in a common misconception that probiotics must ‘colonize’ or alter the composition of your microbiome to “work”. It’s not true.



In fact, outside of specific cases like fecal transplants, there is little evidence that probiotics ‘colonize’, or that they need to. Compared to the tens of trillions of microbes already rooted in your gastrointestinal tract, most probiotics don’t contain enough new bacteria to make a significant difference in the composition of your microbiota.



Even if they did, we don’t know enough about the safety of introducing colonizing microbes (especially soil-based microorganisms, which are becoming popular). Large numbers of newcomers moving in and displacing your existing bacteria could alter the unique balance of your ecosystem within and trigger unintended consequences.



What scientists do know is that, as transient microbes, probiotics travel through your GI tract, interacting with your immune cells, dendritic cells, gut cells, dietary nutrients, and existing bacteria to, directly and indirectly, deliver benefits.



Some enhance the gene expressions involved in tight junction signaling, which help protect against intestinal permeability—this means a tight gut barrier. Others trigger neurotransmitters that stimulate muscle contractions for increased motility—think, better, more regular poops. Yet other bacteria produce byproducts like short-chain fatty acids, which have been extensively shown to be beneficial for metabolic and gut immune health.



This is why, if you choose to take a probiotic, continuous daily intake is important.

4. Probiotics need to be refrigerated to work.

Contrary to other perishable food products, refrigeration doesn’t mean ‘freshness’ or superiority. It’s true that bacteria are fragile—they’re sensitive to light, temperature, and moisture. While some probiotics do need to be refrigerated to preserve efficacy (especially in hotter summer months, or during transport), you shouldn’t discount a probiotic that doesn’t require refrigeration. Technological innovations like lyophilization (freeze-drying) can render probiotics ‘dormant’, meaning they remain in an inert, shelf-stable state until they reach the digestive tract and are reactivated.



The more important thing to look for is demonstrated survivability (through improved delivery technologies like our novel delayed-release capsule technology), regardless of the storage conditions.

5. Probiotics with higher CFUs are always better.

Not necessarily—especially if it contains billions and billions of bacteria never tested in humans.



You’ve probably seen the term CFU on a probiotic label. That refers to colony-forming units, which basically tells you how many bacteria in the sample are capable of dividing and forming colonies. First, a bigger number on the bottle does not always mean better results. The best dose, per strain, is one that has been shown to deliver clinically-validated, positive outcomes in humans.



Second, CFU has become a marketing tool. Many probiotics today proclaim outrageously enormous CFU counts, but are unable to survive the trip from manufacture to store shelf, much less the journey from your mouth, through your acidic digestive process, to your gut. Oftentimes, to get around this, the number on the box will refer to ‘time of manufacture’, when really, it should tell you what amount will still remain viable near the expiration date.



More interestingly, a new form of measurement has emerged—AFU. AFU stands for Active Fluorescent Units. It’s measured with flow cytometry, a process where probiotic cells are tagged with fluorescent ‘markers’ and counted by a laser as they pass through a tube. Through AFU, we are able to calculate a more precise measurement of all viable cells, including ones that are efficacious but not necessarily culturable (and therefore would not be counted in a traditional plated CFU measurement).

6. Probiotics are all the same.