Understanding Your Gut-Brain Connection

We are all familiar with the phrases “go with your gut,” “gut-wrenching experience,” or “butterflies in your stomach.” Although these phrases and idioms might be used in very different situations, they all suggest a connection between our gut and our emotions. Scientists have studied this connection for a long time and have identified how our brain can influence our gut. For example, simply thinking of eating can release stomach juices even without the presence of food. However, recent studies have suggested that the gut-brain connection might go the other way around too.

The Gut-Brain Axis (GBA) refers to the bidirectional communication between the central nervous system and the enteric nervous system. The enteric nervous system (ENS) is made of two thin layers of millions of nerve cells that line your gastrointestinal tract from the esophagus to the rectum.  The main role of the ENS is to control digestion from the swallowing point to nutrient absorption. The ENS connects our cognitive and digestive behavior through communication with our brain.

This communication is linked to various emotional shifts related to the gut. For example, ENS may trigger drastic emotional shifts for people dealing with irritable bowel syndrome (IBS), diarrhea, upset stomach, and even bloating. Studies have also found that a high percentage of people with IBS and functional bowel problems develop depression and anxiety. There are even recent studies that have linked microbiome diversity in the gut to mental health.

This understanding of our gut’s influence over our emotions has led to new treatment opportunities. For example, gastroenterologists have begun to prescribe antidepressants for IBS because some of these medications can give calming effects by acting on nerve cells in the gut. Mind-body therapies are also emphasized with the gut-brain connection. Gut-directed hypnotherapies, yoga, and meditation are proven to improve gastrointestinal issues, improve emotions, and decrease anxiety.

Research surrounding the gut-brain connection presents a holistic view of health where the different systems of the body are recognized as interconnected. Learning about this connection can help you assess your gastrointestinal issues, and to evaluate them alongside the emotions and stressors in your life. For all you know, “butterflies in your stomach” can be more than a simple idiom.

Johns Hopkins: https://www.hopkinsmedicine.org/health/wellness-and-prevention/the-brain-gut-connection
Harvard: https://www.health.harvard.edu/diseases-and-conditions/the-gut-brain-connection
Duke: https://dukeintegrativemedicine.org/DHWBlog/understanding-the-basics-of-the-gut-brain-connection/

Fun Facts About the Anatomy and Physiology of the Stomach

  1. The stomach can hold a lot of food.

When empty, the stomach is pretty small – it is only about the size of your fist. However, it is also capable of stretching to hold up to 4 liters of food – equal to about 8 tubs of Ben & Jerry’s ice cream! This capacity to store food is important: we can eat much faster than we can digest food. It takes anywhere between 6 to 8 hours for food to pass through the stomach and into the intestine, and it can take up to 3 days for food to travel through the entire gastrointestinal tract.

  1. The stomach has many different parts.

Although diagrams of the stomach might make it seem as though it is just a sack, it actually has different parts that perform various functions. The main part of the stomach, the body, is where food is churned and broken down. It is mixed with a cocktail of acidic gastric juices to form a semi-fluid gloopy mass called chyme. The fundus, which forms the upper portion of stomach, is where the air that enters the stomach when we swallow is stored and undigested food is retained before it is mixed in with chyme in the body of the stomach. The lowest part of the stomach is called the pylorus, and it connects the stomach to the small intestine. It prevents the contents of the intestine from rising back up into the stomach when the small intestine contracts.

  1. The acid in our stomach is strong enough to digest most of the organs in the body. It is even strong enough to dissolve some metals!

The cells lining the wall of the upper regions of the stomach secrete hydrochloric acid, which has a pH between 1 and 2. For comparison, that is approximately the pH of the acid in car batteries, and is so acidic that it can dissolve steel. In the body, the hydrochloric acid starts to digest food and kills any microorganisms that might have entered the body along with the food. You might wonder how gastric acid doesn’t digest the stomach itself along with digesting the food it contains. After all, if the acid is strong enough to dissolve steel and cause severe chemical burns if skin were to touch it, the stomach could very well be harmed. The stomach is protected by mucosal cells that secrete a layer of mucus that protect the walls of the stomach. The mucus is 95% water and 5% polymers which give mucus its thick consistency. The mucus contains bicarbonate ions which neutralize some of the hydrochloric acid.

  1. The stomach is the only organ in the digestive system that has three layers of muscles.

Unlike the walls of the rest of the organs in the digestive system, the wall of the stomach is comprised of three layers of muscles. The outer layer is made up of longitudinal muscles, the middle layer is made up of circular muscles, while the inner-most layer – called the oblique layer – has muscles that run diagonally. The outer two layers help in the movement of food down the stomach and into the small intestine, while the inner layer – the layer unique to the stomach –allows the stomach to churn the food and helps in physical digestion. These muscles are why we can digest food even if we are standing on our heads: it is the muscles that move food along the digestive tract, and not gravity!

  1. The stomach is like a small chemical factory.

The stomach secretes a lot of chemicals. As mentioned above, it secretes hydrochloric acid that helps with digestion. It also secretes chemicals that stimulate the secretion of gastric acid. Additionally, it secretes a hormone called ghrelin. Ghrelin is often called the “hunger hormone” because ghrelin levels rise after fasting and make us want to eat!


Scanning for Differences…

If you’ve ever watched dramas such as Grey’s Anatomy, The Good Doctor, or House, you’ll definitely have heard these terms at least once: PET, CT, or MRI. Among the vast array of medical terminology, positron emission tomography (PET), computerized tomography (CT), and magnetic resonance imaging (MRI) scans are perhaps three of the most well-known. Whilst mentioned almost interchangeably, each member of this trio of imaging technology actually differs significantly from each other, but can also work in conjunction with each other. But what are the key differences?

To begin with, CT scans are composed of various X-ray images taken from different angles, generating a more holistic image of the patient’s bones, tumors and even cancers. CT scans are more precise and detailed than normal X-rays, but come with an added cost and radiation intensity. MRI scans, on the other hand, do not involve any form of radiation, instead relying upon a combination of magnetic force and radio waves to observe soft tissues and the nervous system. MRIs also generate images of bones, tumors, and cancers, but are superior to CT scans in terms of image quality and depth. However, this burdens the former with a heftier price tag and slower imaging process than the latter. If you need a more detailed image of your soft tissue, ligaments, or organs, your doctor will commonly suggest an MRI. If you need a general image of an area like your internal organs, or due to a fracture or head trauma, a CT scan is often recommended.

The third and newest form of imaging, the PET scan, differs from the other two imaging techniques due to its focus on imaging organs rather than bones. PET scans are often performed on CT/PET or MRI/PET combination machines, meaning they are used in conjunction with CT and MRI scans. During the procedure, patients are injected with a liquid containing small radioactive particles and sent through a PET scanner that picks up the particles in the organs. Compared to CT and MRI scans, PET scans take almost 10 times as long, require intense preparation and are considered an invasive procedure. They are significantly more expensive and leave trace amounts of radiation in the patient’s system, but are extremely useful in monitoring bodily functions and are more successful at detecting early-stage cancers. PETs yield images that are not as clear as CTs and MRIs, thus using them in conjunction with the latter two allows for an in-depth yet dynamic imaging treatment.

While the three different types of imaging technology have a number of similarities, their primary differences are in the areas of administration, procedure, and risk. While CT and MRI scans are commonly used on structures such as bones, their differences in cost and risk lead to gaps in imaging quality and efficiency. On the other hand, PET scans are used to monitor body functions and prove significantly more efficient at identifying cancers, despite their added risk. So, despite their similarities, none of these technologies can completely compensate for another and, like a lot of things in life, can be used together to strengthen their individual qualities, providing more comprehensive results and saving lives, one scan at a time.


Behind the Scenes of Hunger

What makes us want to eat? We typically base our eating on the physical sensations of hunger and fullness – we eat in response to a grumbling stomach, and we stop when we feel full. Behind the scenes, however, the process is regulated by several hormones.


One of the hormones controlling our appetite is the hormone ghrelin, or, as it is often called ‘the hunger hormone.’ Ghrelin is secreted by the stomach, and the levels of ghrelin circulating in the blood correlate with hunger. Ghrelin levels peak before meals, and dip after we eat in proportion to the size of the meal. Ghrelin levels also depend on the macronutrient composition of the meal. A carbohydrate-dense meal suppresses ghrelin levels to a greater extent than meals dense in fats and proteins. Scientists have found that artificially injecting ghrelin in rodents and humans increases energy intake.


Cholecystokinin is a hormone secreted by the cells of the duodenum. The duodenum is the first part of the intestine, located immediately beyond the stomach. The secretion of CCK has a number of effects: it stimulates the secretion of gastric acid, stimulates pancreatic secretion, and suppresses energy intake. CCK is secreted in response to the intake of food and decreases hunger, with concentrations rising within 15 minutes of eating. CCK levels subsequently fall in 3-5 hours. However, while the role of CCK is known to increase the sensation of fullness during a meal, it’s role in appetite regulation between meals is not as well studied.

Appetite Diagram


Leptin is a hormone secreted by adipose (fat) tissue. Leptin indicates the amount of energy the body has stored in the form of fat, and when it binds to receptors in the hypothalamus, it tells the body to reduce food intake.


Insulin is a hormone secreted by the pancreas. Like leptin, the amount of insulin released is proportional to the amount of fat stored in the body. Insulin decreases appetite, and studies have shown that injecting insulin in rodents reduces both their food intake and their weight. Insulin also stimulates the production of leptin and binds to some of the same targets as leptin in the hypothalamus.

Peptide YY and Oxyntomodulin

Both Peptide YY (PYY) and oxyntomodulin are hormones that are secreted by a special type of cells in the intestine called L-cells. Like CCK, PYY is secreted in response to the intake of food. Studies have showed that a protein and fat heavy diet can lead to greater and longer lasting increases in PYY, leading to reduced hunger for longer durations of time.

Oxyntomodulin is also released in response to the ingestion of food. Studies have showed that oxyntomodulin inhibits the secretion of ghrelin after meals are consumed, contributing to the feeling of fullness. In addition, oxyntomodulin also lowers the rate at which at which the stomach is emptied, further reducing hunger.

These hormones are only part of the story. The brain plays a vital role in the process. Aside from integrating the signals from the hormones, reward signals – such as dopamine when one takes a bite into a favorite dessert – are also integrated in the brain and can also influence appetite and food consumption patterns. The gut microbiome also plays an important but still not entirely understood role in appetite regulation. With increasing rates of obesity, metabolic disorders such as diabetes, and increasing research on the role of such disorders in diseases like Alzheimers or cancer, scientists have begun to study processes like appetite regulation a lot more, and it has shown that the process is much more complex than initially suspected.





What are the Different Types of Stem Cells?

Adult stem cells exist in several parts of the adult body. These cells have the ability to become specialized cells only for the type of tissue in which they exist. For example, liver stem cells can regenerate liver tissue, and muscle stem cells can regenerate muscle fibers, but not the other way around. Adult stem cells are important for replacing dead cells in the tissue and assist in the healing process after tissue injury.

Embryonic stem cells, also called pluripotent, are responsible for the creation of thousands of different cell types that make up our bodies. Pluripotent stem cells are able to create all cell types in the human body, unlike tissue stem cells. However, embryonic stem cells are usually limited during the development period, and are eventually replaced by adult stem cells.

Induced pluripotent stem (iPS) cells are pluripotent cells that are derived from adult tissue using new scientific developments. Scientists have found that when adult stem cells are cultured in the right circumstances, they can revert their differentiation process and go back to the pluripotent state. This means that they can then be used to create any cell type in the body, when placed in the appropriate environment for specialized differentiation. iPS cells are studied extensively in the context of organ generation for transplants, as well as for various types of injuries and diseases.


Stem Cells: What they are and what they do https://www.mayoclinic.org/tests-procedures/bone-marrow-transplant/in-depth/stem-cells/art-20048117

Stem Cells: https://www.closerlookatstemcells.org/learn-about-stem-cells/types-of-stem-cells/


The Brain-Blood Barrier and the Future of Medical Treatments

The blood-brain barrier is a biological structure that acts to maintain a homeostatic environment within the Central Nervous System(CNS). You can think of it as your brain’s wall of defense. The blood-brain barrier is known as a diffusion barrier because it is semipermeable. This means that it only allows some substances to enter the brain while preventing other harmful substances from circulating in the bloodstream and the brain. This can be thought of as a filtration or vetting system.

This semipermeable barrier is achieved through endothelial cells. Endothelial cells line the inside of every blood vessel in the body and form a one-cell-thick later called the endothelium.  The blood-brain barrier is a layer of endothelial cells that selectively allow entry of molecules needed for brain function. Unlike these other blood vessels in the body, the endothelial cells in the brain are tightly wedged together which creates the semipermeable boundary between the brain and bloodstream. The molecules that are permitted entry through this boundary are amino acids, oxygen, glucose, and water. This ensures that the right balance of hormones, nutrients, and water is flowing throughout the brain.

Research surrounding the blood-brain barrier and medical treatments has many challenges. Most drug treatments are unable to pass through the barrier, which is why drug development for brain diseases have poor success rates compared to the development of drugs in other areas of the body. In cancer, for example, the blood–brain barrier is largely responsible for the failure of brain of cancer treatments. The blood-brain barrier actively pumps selected molecules into or out of the brain and can prevent the drugs from entering the brain. In many instances where the cancer drugs do manage to cross the blood-brain barrier, they are promptly kicked back out by active efflux pumps<. Another issue with the blood-brain barrier and cancer treatments lies in the fact that the molecules that can easily slip across the barrier tend to be small and highly lipid-soluble. This presents a challenge since many lipid-insoluble biological drugs have improved outcomes for many other types of cancer.

Despite the challenges of the blood-brain barrier and cancer treatments, studies have proven that your brain’s wall of defense can also act as a potential noninvasive treatment tool for many neurological diseases. Through extensive studies, scientists have found that very small compounds or compounds that are lipid-soluble can pass through the endothelial cells of the blood-brain barrier with almost no effort. These compounds include antidepressants, anti-anxiety medications, alcohol, cocaine, and many other hormones. The passing of larger molecules such as glucose or insulin is also possible with the help of transporter proteins.

Blood-brain barrier research does not stop there. There are currently several ways that researchers are attempting to combat the challenges of the blood-brain barrier and medical treatments. One example of this is the development of cyclic peptides that can enhance the penetration of the blood-brain barrier. This is achieved by attaching the cyclic peptides to the surface of nanoparticles. This creates a drug nanocarrier for drug delivery through the blood-brain barrier, which is promising for the future effectiveness of drug delivery to the brain.

The future of medical treatments through the use of the blood-brain barrier continues to move forward. As scientists continue to explore this biological barrier, new and noninvasive treatments will arise to address cancer and other neurological diseases.

NCBI: https://www.ncbi.nlm.nih.gov/books/NBK519556/
Science Daily: https://www.sciencedaily.com/releases/2019/10/191011095933.htm
Cure Alzheimer’s Fund: https://curealz.org/the-research/topics-of-interest/blood-brain-barrier/
Nature: https://www.nature.com/articles/d41586-018-06707-4
Pharma Tech: https://pharma.nridigital.com/pharma_jul20/breaking_blood-brain_barrier_neurology

OTTer Fun Facts


Otters LOVE Rocks: Otters often have a favorite rock to open their shellfish! Each otter stores a favorite rock in its chest pouch that is unique to them and their preference. The otter loves to keep this tool close when gathering food. Every otter has a pouch for storing food, that is not super noticeable, but an important part of the otter’s body. Source: The Little Book of Otter Philosophy.

Otters Have a Unique Smelly Poop: Weird fact of the day is Otters have a particular stink to their feces. So much so, that this poop is coined, “Spraints.”

Otter Pregnancy: Otter gestation can last up to two months, but otters do not begin to breed until they are at least five years old. In fact, otter pregnancy is unique to this animal. The otter can have a delayed implantation of a fertilized egg into the uterus. Therefore, a baby otter can be born up to a year after fertilization has occurred. A female otter can have one up to six babies per litter. Baby otter births typically will occur from the months of November to May.

Otter Fur:  Did you know otters have the thickest fur of any mammal? Otters have up to 850,000 to one million hairs per square inch. Source: The little Book of Otter Philosophy, Home and Environment.

Otters are Nocturnal Animals! Typically, otters will hunt at night. Source: The Little Book of Otter Philosophy, Work and School.

Otters are Team Players: Did you know otters love to relax in a group setting? In fact, researchers from Alaska have observed otters in groups of over one thousand floating in the water. These friendly creatures can be seen relaxing in groups from ten to hundreds. Source: The Little Book of Otter Philosophy.

One Big Breath! Otters have massive lung capacity. Depending on the type of otter they can hold their breath for up to eight minutes. [Source: The Little Book of Otter Philosophy]

It’s All About Looking Good: The sea otter will spend much of its time grooming itself. In fact, looking this good can take up to six hours! However, the reason that otters will spend time cleaning themselves is so that their fur will remain buoyant (keeping them afloat) and dry.  Source: The Little Book of Otter Philosophy.

CIA Agent or Otter?  Recently, declassified records from the 1960’s, found that the CIA studied otters in the 1960’s. Known as the, “MK Ultra Project.” This project designed an otter harness. The reasons are still unknown, but believed to be so that otters could deliver explosives or microphones to sensitive areas to create an otter dossier. Source: The Little Book of Otter Philosophy.

Otters Love to Chase Their Own Tails: Check out this link!

Otter Cafes: In Japan or areas of Asia, “Otter Cafes” have become a popular commodity. Clients pay to pet and play with otters. This idea venture, while cute, is questionable due to the endangered subset of populations.


Bet You Didn’t Know this about the Gut Microbiome!

When the word “symbiosis” comes up, people typically think of lichens – composite organisms established from fungi and algae. Or they think about clownfish and sea anemones – a relationship seared in our memories thanks to Finding Nemo. Humans, however, don’t come to mind. It turns out, however, that we are helped by millions of bacteria that live inside us. These bacteria are not only more numerous than we might guess, but also play roles extending beyond digestion. Here are some interesting facts about the gut microbiome:

  1. The gut microbiome is enormous – there are upwards of 30 trillion bacterial and fungal cells in the gastrointestinal tract, most of which reside in the colon. This makes the number of microorganisms housed in the gastrointestinal tract equal to, if not slightly higher than, the number of cells that compose the human body itself!
  2. While the number of human cells might just equal the number of cells constituting the gut microbiome, the number of genes encoded by the human genome is no match for the number of genes encoded by the gut microbiome. The gut microbiome encodes approximately 150 times the number of genes encoded by the human genome.
  3. These extra genes come in handy to humans. These genes allow the bacteria to produce an array of enzymes that help humans digest complex carbohydrates in the large intestine and extract nutrients from them. In the absence of these enzymes, the human body would not have been able to get nutrients from a lot of the food we consume.
  4. The gut microbiome also helps synthesize vitamins B and K in the body. Vitamin B plays an important role in metabolism, while vitamin K is required for blood clotting. The gut microbiome also helps the body absorb chemicals such as phytochemicals and polyphenols that function as antioxidants.
  5. Our diet influences the composition of our microbiome. Those who consume a plant-based diet and those who consume a diet rich in animal-based-products have gut microbiomes that are enriched in different bacterial species. Consumption of foods rich in probiotics can also help alter the composition of the gut microbiome.
  6. The gut microbiome plays an important role in modulating inflammation. Inflammation is a process by which the body stimulates the immune system by secreting chemical signals called cytokines. While this system is beneficial If the body is being invaded by pathogens, continuous inflammation leads to tissue damage. While some bacteria can protect against chronic inflammation by producing anti-inflammatory cytokines, some species can cause inflammation as well.
  7. A disrupted microbiome – particularly a disruption in which there is an over-enrichment of microbes that cause inflammation – has been associated with numerous diseases including irritable bowel syndrome (IBS), inflammatory bowel disease (IBD), colorectal cancer, and type II diabetes. While it may seem difficult to believe that the microbes in the gut can play a role in notoriously complicated diseases like IBD, fecal transplants from healthy individuals that aim to rebalance the microbiome of a patient suffering from IBS or IBD have led to an alleviation of symptoms.
  8. The gut microbiome can even regulate mood and memory – aspects of the functioning of the human body that don’t seem connected with the gut and digestion at all. In fact, the gut microbiome produces numerous neurotransmitters that regulate mood, including serotonin, the hormone that causes the feeling of well-being and happiness.

New research has only begun to elucidate the complex connection between the food we consume, the bacteria in the gut that help digest it, and the resultant effect on our long-term health. The interconnectedness between the bacteria in the gut and the chemical responses they stimulate in the body is evidence of the complex ways in which organisms depend on one another, and how the tiniest of organisms can have massive impacts on our health.














15 Good Minutes: Hee Cheol Cho

Issues surrounding cardiovascular health and disease are personal for Dr. Hee Cheol Cho. Dr. Cho lost his father to a heart attack, and his father lost his siblings to heart attacks. “The topic of cardiovascular disease is embedded in my family and blood,” Dr. Cho said.

Hee Cheol Cho, Ph.D. is a stem cell and cardiology researcher, Urowsky-Sahr Scholar in Pediatric Bioengineering, and Associate Professor at the Departments of Biomedical Engineering and Pediatrics at Emory and Georgia Tech. Dr. Cho’s research focuses on cardiac pacemaker cells and developing a gene-and cell-based treatment for cardiac arrhythmia. His “biological pacemaker” is a minimally invasive alternative treatment for cardiac arrhythmia.

Hee Cheol Cho, Ph.D.

Hee Cheol Cho, Ph.D.

Cardiac arrhythmia refers to irregular heartbeats that can cause fatigue and, in more severe cases, unconsciousness. To correct the heartbeats, an electrical pacemaker is often implanted. This implanting of electric pacemakers is not considered suitable for pediatric patients, and it is an invasive procedure. There are also several drawbacks of the device, including battery replacement, dislodging of the lead wire, and risk of infection. Dr. Cho and his research team have developed a device-free pacemaker, using a small molecule to convert heart muscle cells to pacemaker cells to restore natural heart rhythm.

Dr. Cho’s research also addresses myocardial infarction. Myocardial infarction, commonly known as a heart attack, is an abrupt blockage of the heart vessel that supplies the blood to the heart.  When the circulation is cut off, then the heart vessel will begin to die within hours. The heart cannot regenerate itself, and once the muscle begins to die it will be replaced with fibrotic tissue that leaves a big scar.

In the lab, Dr. Cho and his team pursue knowledge and understanding of how stem cells arrive at heart muscle cells and what kind of growth factors we can add or subtract so that we get the heart muscle cells that we want to replace the damaged muscles.

“We are at the point where we can reasonably specify which road the stem cells will take to become either atrial or ventricular heart muscle cells. In our latest discovery, we found a way to make these stem cells become left or right ventricular cells and that’s important because when the myocardial infraction happens and the damage is in the left ventricle, then we want to implant in the left ventricle. We have arrived at a point where we can specify this.”

Beyond his personal connection, Dr. Cho has many other inspirations and influences for entering this line of work. “My parents and my family have been the initial influencer of my career, but the proverb ‘it takes a village to raise a child’ applies to me as well,” Dr. Cho said.  “In the early years of my training, my Ph.D. supervisor and post-doctoral mentor all have given me such excellent training and mentorship to form me as a scientist. Now that we have this research team, my young and talented, and seasoned scientists all influence me. Their dedication, work, and their exciting discoveries are all humbling to me and give me such great satisfaction as they grow. These past few years I have also developed relationships with patients and their families. When I speak and communicate with young people with cardiac pacemakers and want to play sports again and see how our research gives them hope, it is a motivation to me and my career.

As Dr. Cho described his work, he had a few words of advice for aspiring scientists and his past self: “If I could rewind 20 years from today, then I think I would tell myself to ‘be the best version of yourself.'”

The Pros of Probiotics

You might have heard the word “probiotics” before. You might have seen it written across yogurt containers, or heard advertisers pitch that their new health drink is full of probiotics. But you might not know exactly why – and how – they are good for you. Here is a breakdown.

What are probiotics?

The Food and Agriculture Organization of the World Health Organization (WHO) defines probiotics as “live microorganisms which when administered in adequate amounts confer a health benefit to the host.” In short, they are microorganisms – typically bacteria – that are good for us. Probiotics are able to survive the acidic environments of the stomach and intestines. They are capable of adhering to the walls of the gastrointestinal tract and show antimicrobial activity against pathogens.

Which organisms are considered probiotics and where are they found?

There are numerous microorganisms that are considered probiotics, but species under the genus Lactobacillus or the genus Bifidobacterium are the ones that are most commonly referred to.

Probiotics are found in most fermented food. Yogurt is a good, easily available source of probiotics. Other sources include pickles, kimchi, tempeh, sauerkraut, kombucha, and certain types of cheese.

How are probiotics good for you?

The first scientist in the Western world to publish work on the benefits of probiotics was Russian zoologist and 1908 Nobel Prize winner, Ilya Metchnikoff. He wrote that people living in Eastern Europe had greater life expectancy and noted that they lived largely on milk that was fermented by lactic acid bacteria. He proposed that the microorganisms in the colon produced toxic chemicals that led to aging, but consuming the fermented milk helped populated the intestine with lactic acid bacteria that reversed the aging process.

Today, studies have shown that probiotics can improve certain gastrointestinal disorders.

  1. Antibiotic-associated Diarrhea (AAD)

Antibiotic-associated diarrhea is caused because of an imbalance in the gut microbiome due to the consumption of antibiotics. Antibiotics, in addition to killing pathogenic bacteria, kill some of the good bacteria that are important for digestion. Estimates show that anywhere between 5-39% of patients suffer from AAD. Probiotics can help restore and normalize the gut microbiome when antibiotics are prescribed.

  1. Clostridium difficile Infection

A mild Clostridium difficile infection typically leads to diarrhea and mild abdominal cramping. Severe infections, however, can even be life threatening and can lead to extreme diarrhea, severe abdominal cramping, weight loss, and dehydration, and can even lead to kidney failure. The infection takes place because C. difficile colonizes the intestine and releases toxins which cause diarrhea. Treatments are not usually fully effective, and patients relapse because some C. difficile spores evade treatment and survive. Studies have shown that probiotics can help prevent and improve symptoms of C. difficile infections.

  1. Colorectal Cancer

Colorectal cancer refers to any cancer that affects the colon or the rectum. There is evidence that indicates that diet – and probiotics – can reduce the risk of cancers, particularly colorectal cancer. As elaborated in more detail below, probiotics help protect against colon cancer by modifying the composition of the gut microbiome, and lowering the number of bacteria that produce harmful, carcinogenic biproducts. Probiotics produce chemicals that inhibit cell proliferation and act as detoxifying agents. Probiotics can also help in the elimination of carcinogenic compounds from the body.

How do probiotics work?

While there isn’t a single definite answer for how probiotics work, scientists have a few models explaining how they benefit the body.

  1. They reduce the degree of colonization of the gastrointestinal tract by pathogenic bacteria through competition. Probiotic microorganisms compete for binding sites on the walls of the intestines and compete for nutrients. This is one of the methods that scientists believe could be at play with respect to probiotics being able to reduce the risk for cancer. Studies have shown that patients with colorectal cancer have lower numbers of Lactobacillus (probiotic bacteria) and higher levels of Salmonella and Clostridium, which are involved in the pathogenesis of colorectal cancer. Probiotic bacteria can grow at the expense of bacteria like Salmonella and Clostridium, reducing the risk of cancer.
  2. There is research that suggests that probiotics could help degrade receptors in the walls of the gastrointestinal tract that bind toxins. boulardii, a yeast, helps protect against C. difficile infection symptoms by degrading the toxin receptor on the intestinal mucosa.
  3. Probiotic bacteria produce a variety of chemicals including organic acids, hydrogen peroxides, and bacteriocins that inhibit the activity of harmful bacteria. Enzymes produced by bacteria in the intestines – while helping with digestion – can produce carcinogenic biproducts. Organic acids and hydrogen peroxides produced by probiotics acidify the intestinal environment and can inhibit the biochemical activities of these enzymes, reducing the number of carcinogens produced.
  4. Probiotics help in the elimination of carcinogens. Carcinogenic compounds bind to the cell walls of probiotic bacteria and are eliminated through feces.
  5. Probiotics produce compounds that have anticarcinogenic activity. Probiotics produce short chain fatty acids which serve as a source of energy for colonocytes and promote the death of cancer cells.

Recent research has shown that the microbes in the gut play a vital role in our overall wellbeing. A lot of questions about how probiotics influence the gut microbiome remain unanswered, in no small part because accessing the gut microbiome to study isn’t easy – it requires invasive surgery. What is clear, however, is that probiotics don’t just give yogurt and kombucha the unique taste that most of us enjoy, but also provide us several surprising health benefits.