The Kingdom in Your Gut
With one hand resting on your tummy imagine for a moment the trillions of microscopic organisms, or microbes, residing in your gut. Just as these microbes rely on us for a welcoming place to live, we rely on them for digestive support and immune system functioning. Their health supports our health and vice versa.
In 2012 the University of California San Diego launched the American Gut Project (AGP), which has collected thousands of microbe samples from volunteers in over 40 countries. Although AGP detected over 467 million different species in the fecal samples, scientists believe the actual number of gut microbes is higher as some strains cannot survive outside the human body long enough to be identified.
Your particular microbic community is as unique as your fingerprint yet constantly in flux depending on your diet, medications, environmental factors, age and emotions. A wide diversity of microbial species in our gut correlates with better health.
Analysis of the AGP data revealed that gut biodiversity varies by geography, diet and lifestyle factors such as stress management, exercise and time in nature. In general, people in the UK have a more diverse gut microbiome than people from the US. People diagnosed with depression have similar microbiota regardless of where they live while people who consume a wide variety of fruits and vegetables have the most robust and diverse gut microbiomes.
A wide diversity of microbial species in our gut correlates with better health.
Your mother provided your first colony of microbes when you were born. We also collect microbes from soil, pets, and other people.
Fermented foods such as yogurt, sauerkraut, kimchi, miso, kombucha, pickles and tempeh provide probiotics. It is important to check the labels to ensure that the product you are consuming contains live cultures.
Researchers have developed a process to transfer bacteria from a healthy donor to patients with a compromised gut. Earlier this year the American Gastroenterological Association issued a recommendation for fecal microbiota transplant (FMT) for patients with recurrent Clostridioides difficile (C. diff) infections that do not respond to standard treatment. More research is needed before FMT is recommended for other digestive ailments.
Do You Need a Probiotic Supplement?
Probiotics are one of three types of bacteria living in our digestive system (the other two are commensals and pathobionts). Growing awareness of gut health is feeding demand for over-the-counter (OTC) probiotic supplements. Estimates vary but the global probiotic market may be worth $71 billion in 2024 and is projected to grow 8% over the next five years.
While there is widespread perception that probiotic supplements support gut health, a 2019 meta-analysis in MicrobiologyOpen noted that there is no long-term clinical evidence to support this notion.
To be effective, probiotic bacteria must be alive when ingested. Of the plethora of probiotic species, only a subset can survive the heat and pressure inherent in the manufacturing process as well as the journey to store shelves in commercial trailers. The supplements industry is loosely regulated so some products may contain less live bacteria than advertised or include microorganisms not listed on the label.
While OTC probiotic supplements appear to be effective for preventing conditions such as antibiotic-related or traveler’s diarrhea, constipation, irritable bowel syndrome or vaginitis, success depends on ingesting the specific strain known to be susceptible to these conditions. The Alliance for Education on Probiotics (AEProbio) maintains a clinical guide to OTC brands for specific health concerns.
Probiotics are not benign. Some people experience gas and bloating from probiotics although manufactures advise that the symptoms will resolve over time. People with pancreatitis, recent surgery or suppressed immune systems are advised to avoid taking probiotic supplements. If taking an antibiotic, wait at least two hours before taking a probiotic supplement.
Probiotics Need Prebiotics to Survive
The continued survival of probiotic colonies relies on our ingestion of prebiotics; in other words, we have to eat when they eat or they will starve. Prebiotic foods contain a type of carbohydrate that we cannot digest, which enables it to withstand the acidic juices in the stomach and reach the probiotics living in our intestines.
Prebiotic foods are typically high in fiber. Examples include raw leafy green vegetables, asparagus, onions, garlic, leeks, raw fruits, oats, barley, nuts, seeds and legumes. Proceed slowly when introducing high-fiber foods into your diet so your digestive system can adjust.
Do You Need a Probiotics Supplement?
In certain situations such as an antibiotic regime or excessive stress, probiotic supplements may give our gut a boost. But considering that only a subset of probiotic species can be bottled, most of the time we can rely on fermented foods plus a wide variety of fruits and vegetables to provide the probiotics and prebiotics that our gut microbiome needs to thrive. Based on the AGP analysis, experts recommend consuming 30 or more types of fruits and vegetables each week.
If you take OTC probiotic supplements on a regular basis, I would love to hear about your experience. Drop me an email.
You Are Your Microbes
AGP scientist Rob Knight explains why “The three pounds of microbes that you carry around with you might be more important than every single gene you carry around in your genome.”
Join the Research
There is still so much to discover about the gut microbiome and its effect on our overall health. The AGP is now the Microsetta Initiative. You can contribute your microbes to the database.
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REFERENCES
Are probiotics actually beneficial?
Advanced Science News, Oct 2023
Clinical Guide to Probiotic Products Available in the US
Role of Probiotics in Human Health
Cureus Nov 2022
An examination of data from the American Gut Project reveals that the dominance of the genus Bifidobacterium is associated with the diversity and robustness of the gut microbiota
Microbiologyopen Sept 2019
Probiotics Market by Product Type
Markets and Markets, Mar 2024
AGA now recommends fecal microbiota transplant for the majority of recurrent C. diff patients
AGA website, Feb 2024
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