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Unwilding Our Body
Rehab for the Microbiome Dirty Children Grow into Clean Adults Disease Begins in our Microbiome Know your Microbiome Renewal of Microbiomes Microbiomes: The Worker Bees Predominant Bacteria in Humans What do Bacteria do? You're only as Healthy as your Gut Bacteria Relevance of vegan gut microbiota on human and diseases |
OBJECTIVES:
REFERENCES:
- Describe the Role of Microbiome in Human survival
- Discuss factors influencing the composition of Microbiome
- Identify ideal diet that may improve the microbiota
- Discuss the relevance of microbiome in human diseases
REFERENCES:
- Robynne Chutkan, The Microbiome Solution
- Brenda Davis, The Diet and Lifestyle Guide
- Jessica M. Finlay; B. Brett Finlay, The Whole-Body Microbiome
- Michael Greger, Nutrition Facts
Unwilding our Body
Our ancestors had a symbiotic relationship with their microbes that evolved over millions of years and served them well. They were benevolent hosts to a dense jungle of microscopic creatures, including worms and other parasites that actually contributed to their health. Large predators and the absence of food were their main threats, not the hundreds of diseases that afflict us today. The irony is that as we've "unwilded" our bodies and our environment in an effort to become healthier, we've actually become a lot sicker in some important ways. Urbanization and modern medicine have undoubtedly improved our lives, but they've also introduced practices - overuse of antibiotics, chlorination of the water supply, processed foods full of chemicals and hormones, microbe-depleting pesticides, increasing rates of cesarean sections - that have ravaged our microbiome, diminishing the total number of organisms as well as the diversity of species. The result is an increase in a wide range of modern plagues, including asthma, allergies, autoimmune diseases, diabetes, obesity, cancer, irritable bowel syndrome, anxiety, and heart disease. The rise of these diseases is inextricably intertwined with the full-on assault on our microbiome resulting from our super-sanitized lifestyle.
A decade ago, who knew that every antibiotic dispensed during cold and flu season was potentially bringing us one step closer to a diagnosis of Crohn's disease, or making us fatter? None of us doing the prescribing realized that we might be paving the way to real illness in our well-meaning attempts to cure the sniffles. The prevailing wisdom was - and to some extent still is - that germs are bad and we should get rid of them, and antibiotics are good and we should use them. Despite tremendous amount or research in the last few years connecting the dots, many physicians and their patients remain in the dark, blaming each manifestation of microbial discord on bad luck or bad genes, never questioning or understanding the root cause.
Rehab for the Microbiome
Gastroenterologist may everyday observe in their practice, seeing patients with the telltale signs or a disordered microbiome: bloating, leaky gut, Irritable bowel, gluten intolerance, Crohn's disease, ulcerative colitis, eczema, thyroid disorders, weight problems, fatigue, and brain fog. It's a veritable epidemic of "missing microbes," as infectious disease specialist Martin Blaser, MD, describes it. The symptoms vary, but the history doesn't: overzealous use of antibiotics, often accompanied by a highly processed Western diet low in indigestible plant fiber - the preferred food of gut bacteria.
Repopulating the microbiome can be a challenging process, but the good news is that most people do get better. Your microbes are constantly changing and evolving, and even if they've been severely damaged by med1cations, infection, or diet, paying attention to what you put in and on your body can yield huge improvements. The microbiome you have today isn't the one you were born with, nor is it the one you'll have next year or even next week. Its highly dynamic, constantly changing and adjusting in response to your internal and external environment.
Dirty Children Grow into Clean Adults
People spent their early childhood eating food from farm, grown in rich soil fertilized by a herd of goats instead of chemicals. Living in the hilly suburbs and roaming around outside with the dog after school, exploring gullies, picking mangoes or other fruits from the backyard, and acquiring the occasional case or pinworm as a result of being barefoot explorations. The usual medical advice before for common ailment - from the flu to a sprained ankle - was always the same: go lie down and you'll feel better in the morning. People were vaccinated for the big stuff (polio and small pox) but didn't sweat the small stuff (chicken pox). But you will notice that children in this generation may have more visits to the doctor before they were in preschool than their parents had in their entire lifetime. So, despite the dirty childhood filled with organic, homegrown food, protective parasites, lots of time outdoors, and limited contact with an overzealous medical system, how people end up in adulthood with not one but three manifestations of microbial discord: eczema, rosacea, and yeast overgrowth? It took a while.
Potent microbial disruptors like the antibiotics prescribed in college for acne and twenty years of birth control pills with no ill effects. But as life got more complicated, unrelenting stress and the cookies, cakes, and candy people consumed to combat it were their ultimate undoing. A Western diet high in sugar and fat promotes growth of the wrong types of bacteria in your gut, and a lifestyle that leaves literally no time to go outside and smell the roses can be the straw that breaks the camels back, particularly if you have additional risk factors, such as significant antibiotic use.
Disease Begins in our Microbiome
Poor nutrition and stress can unmask the effects of a damaged microbiome and lead to a multitude of symptoms: a decline in overall well-being characterized by seemingly unrelated conditions that appear out of nowhere, leaving them scratching their head and wondering what's going on.
Microbial disruptors are everywhere - in the food we eat, the water we drink, the products we use, and the medications we take and the clinical manifestations of a disrupted microbiome are varied and show up in people of all ages and stages. Chances are there's someone in your family with asthma, allergies, eczema, thyroiditis, diabetes, arthritis, or any of the many disorders that we're now discovering have the same root cause. A damaged microbiome isn't the only reason people develop these conditions, but it's often a major contributor that interacts with genetic and environmental factors to create a perfect storm or disease. That's why it's more important than ever to understand the complex and critical role bacteria play in our health, so that if and when yours is compromised, you can connect the dots and start to heal yourself.
Microbial disruptors are everywhere - in the food we eat, the water we drink, the products we use, and the medications we take and the clinical manifestations of a disrupted microbiome are varied and show up in people of all ages and stages. Chances are there's someone in your family with asthma, allergies, eczema, thyroiditis, diabetes, arthritis, or any of the many disorders that we're now discovering have the same root cause. A damaged microbiome isn't the only reason people develop these conditions, but it's often a major contributor that interacts with genetic and environmental factors to create a perfect storm or disease. That's why it's more important than ever to understand the complex and critical role bacteria play in our health, so that if and when yours is compromised, you can connect the dots and start to heal yourself.
The new paradigm of bacteria as friend rather than foe is at the heart of a revolution in health care that's forcing us to reexamine how we live, as well as our medical practices, with new microscopic eyes, and to consider how modern life and our everyday choices affect the life of our microbes - and how our microbes in turn affect us. What has become very clear is that our individual and collective health depends on it.
Know your Microbiome
Our microbes are intimately involved in every aspect of our health from ensuring our digestive well-being to influencing our likelihood of being obese and our risk of developing cancer or diabetes. They even play a role in our brain chemistry and mental health, affecting our moods, our emotions, and our personalities. We are, it seems, single individuals comprised of multiple living, breathing, moving parts. The more we learn about this fascinating microscopic community, the clearer it becomes that our fate is inextricably tied to theirs, making it essential that we learn more about where our microbes come from, what they do, and why we literally can't live without them.
The microbiome refers to all of the organisms that live in or on your body: all of the bacteria, viruses, fungi, protozoa, and helminths (worms, for those of us who have them), as well as all of their genes. A staggering hundred trillion microbes that include thousands of different species inhabit your nooks and crannies - with more than a billion bacteria in just one drop of fluid in your colon alone.
Your unique microbial footprint develops over your lifetime, and it reflects everything about you: your parents health, how and where you were born, what you've eaten (including whether your first sips were breast milk or formula), where you've lived, your occupation, personal hygiene, past infections, exposure to chemicals and toxins, medications, hormone levels, and even your emotions (stress can have a profound effect on the microbiome). The end result is a microbial mix so distinctive from person to person that yours is a more accurate identifier of you than your own DNA.
We've known about the microbiome since the 1600s, when Antoni van Leeuwenhoek first looked at his own dental plaque under the microscope and described "little living animalcules, very prettily a-moving." But it's taken us a few centuries to figure out that these fellow travelers might actually be helping rather than hindering us, with a specific purpose that's very much aligned with our own survival. The overwhelming majority or our microbes aren't germs that cause disease. Quite the contrary-they're an essential part of our ecosystem and play a vital role in keeping us healthy.
How do we get from germ-free fetus to living, breathing petri dish, colonized with trillions of bacteria? Let's start at the cradle and work our way toward the grave, to find out exactly how our microbiome evolves and the crucial role it plays at every stage in our development.
Your unique microbial footprint develops over your lifetime, and it reflects everything about you: your parents health, how and where you were born, what you've eaten (including whether your first sips were breast milk or formula), where you've lived, your occupation, personal hygiene, past infections, exposure to chemicals and toxins, medications, hormone levels, and even your emotions (stress can have a profound effect on the microbiome). The end result is a microbial mix so distinctive from person to person that yours is a more accurate identifier of you than your own DNA.
We've known about the microbiome since the 1600s, when Antoni van Leeuwenhoek first looked at his own dental plaque under the microscope and described "little living animalcules, very prettily a-moving." But it's taken us a few centuries to figure out that these fellow travelers might actually be helping rather than hindering us, with a specific purpose that's very much aligned with our own survival. The overwhelming majority or our microbes aren't germs that cause disease. Quite the contrary-they're an essential part of our ecosystem and play a vital role in keeping us healthy.
How do we get from germ-free fetus to living, breathing petri dish, colonized with trillions of bacteria? Let's start at the cradle and work our way toward the grave, to find out exactly how our microbiome evolves and the crucial role it plays at every stage in our development.
PREGNANCY
Long before we enter the world, our mother's microbiome starts to prepare for our arrival. One of the most dramatic changes happens in her vagina. During pregnancy, cells in the vaginal lining ramp up production of a carbohydrate called glycogen, sending glycogen-loving Lactobacillus bacteria into a feeding frenzy and increasing their numbers. Lactobacilli convert lactose and other sugars to lactic acid, creating an acidic, unfriendly environment that helps to protect the growing fetus from potential invaders.
Bacteria don't just protect us from undesirable germs that can enter via the vagina; they also nurture us. In the third trimester of pregnancy, Proteobacteria and Actinobacteria species increase in number and cause a corresponding rise in the mother's blood sugar and weight gain in her breasts, with the specific goal of ensuring adequate growth and breast milk for the baby. Transplanting gut bacteria from late-trimester pregnant women into nonpregnant mice produces identical changes in the mice-confirming that the transformation is indeed mediated by gut bacteria, not hormones.
Long before we enter the world, our mother's microbiome starts to prepare for our arrival. One of the most dramatic changes happens in her vagina. During pregnancy, cells in the vaginal lining ramp up production of a carbohydrate called glycogen, sending glycogen-loving Lactobacillus bacteria into a feeding frenzy and increasing their numbers. Lactobacilli convert lactose and other sugars to lactic acid, creating an acidic, unfriendly environment that helps to protect the growing fetus from potential invaders.
Bacteria don't just protect us from undesirable germs that can enter via the vagina; they also nurture us. In the third trimester of pregnancy, Proteobacteria and Actinobacteria species increase in number and cause a corresponding rise in the mother's blood sugar and weight gain in her breasts, with the specific goal of ensuring adequate growth and breast milk for the baby. Transplanting gut bacteria from late-trimester pregnant women into nonpregnant mice produces identical changes in the mice-confirming that the transformation is indeed mediated by gut bacteria, not hormones.
In addition to our founding species of bacteria, we also receive protective antibodies from our mother through the placenta. Armed with these antibodies and our own few but plucky microbial soldiers, we're ready to make our entrance into the world. But exactly how we enter isn't just a matter of convenience it has significant microbial repercussions that continue to affect our health well into adulthood.
BIRTH
During a normal delivery, the baby's head turns to face the mother's rectum as it crowns and exits the birth canal. This turning brings the baby's nose and mouth into direct contact with her vaginal and rectal contents. What better way to get inoculated with a good dose or bacteria than to come face-to-tush with the source? A study published in Proceedings of the National Academy of Sciences showed that babies born vaginally are colonized with Lactobacillus species and other "good bacteria," while babies born by C-section tend to have more common hospital "bad bacteria" like Staphylococcus that are associated with illness and infection.
This brief act of swallowing a mouthful of our mother's microbes as we enter the world confers unbelievably important benefits. It turns out that exposure to bacteria is a critical early step in the development of our immune system. C-sections bypass this crucial event and are associated with higher rates of asthma, allergies, obesity, type 1 diabetes, and other autoimmune conditions.
During a normal delivery, the baby's head turns to face the mother's rectum as it crowns and exits the birth canal. This turning brings the baby's nose and mouth into direct contact with her vaginal and rectal contents. What better way to get inoculated with a good dose or bacteria than to come face-to-tush with the source? A study published in Proceedings of the National Academy of Sciences showed that babies born vaginally are colonized with Lactobacillus species and other "good bacteria," while babies born by C-section tend to have more common hospital "bad bacteria" like Staphylococcus that are associated with illness and infection.
This brief act of swallowing a mouthful of our mother's microbes as we enter the world confers unbelievably important benefits. It turns out that exposure to bacteria is a critical early step in the development of our immune system. C-sections bypass this crucial event and are associated with higher rates of asthma, allergies, obesity, type 1 diabetes, and other autoimmune conditions.
BREAST-FEEDING
Human milk oligosaccharides (HMOs) are the third-most common ingredient in breast milk, despite the fact that they're completely indigestible by infants. HMOs are indigestible because they're not there to feed the baby. They're there to feed the baby's bacteria specifically, Bifidobacterium, present in high numbers in breast-fed infants. Bifidobacterium repels Staphylococcus and other harmful microbes on the mother's nipple, so it's an essential part of the baby's microbial arsenal. While Bifidobacterium gorges on HMOs, Lactobacillus in the newborn's gut breaks down sugars and the other digestible components of breast milk - an incredibly well-designed example of the symbiotic relationship between humans and microbes.
Human milk oligosaccharides (HMOs) are the third-most common ingredient in breast milk, despite the fact that they're completely indigestible by infants. HMOs are indigestible because they're not there to feed the baby. They're there to feed the baby's bacteria specifically, Bifidobacterium, present in high numbers in breast-fed infants. Bifidobacterium repels Staphylococcus and other harmful microbes on the mother's nipple, so it's an essential part of the baby's microbial arsenal. While Bifidobacterium gorges on HMOs, Lactobacillus in the newborn's gut breaks down sugars and the other digestible components of breast milk - an incredibly well-designed example of the symbiotic relationship between humans and microbes.
INFANCY
When we are babies, everything eventually ends up in our mouth. It's one of the ways we interact with our environment. Its also one of the ways our environment interacts with our microbiome, allowing bacteria from our home, our siblings, and even our pets to gain access to our gut and help train our immune system to distinguish friend from foe. Factors like family size, early nutrition, and the quality of our water supply have a profound effect on our blossoming microbiome.
Not surprisingly, as infants our microbiome most closely resembles that of other household members, especially our mothers. But it's a constantly changing and evolving mix, with lots of species diversity, and events like a fever, a dietary change, or a course of antibiotics can have a major ripple effect. Within a few weeks after birth, bacteria in various parts of our body start to branch out and specialize, and within a few months, the number of species starts to rise, increasing from about a hundred in infancy to a thousand or more by adulthood.
When we are babies, everything eventually ends up in our mouth. It's one of the ways we interact with our environment. Its also one of the ways our environment interacts with our microbiome, allowing bacteria from our home, our siblings, and even our pets to gain access to our gut and help train our immune system to distinguish friend from foe. Factors like family size, early nutrition, and the quality of our water supply have a profound effect on our blossoming microbiome.
Not surprisingly, as infants our microbiome most closely resembles that of other household members, especially our mothers. But it's a constantly changing and evolving mix, with lots of species diversity, and events like a fever, a dietary change, or a course of antibiotics can have a major ripple effect. Within a few weeks after birth, bacteria in various parts of our body start to branch out and specialize, and within a few months, the number of species starts to rise, increasing from about a hundred in infancy to a thousand or more by adulthood.
CHILDHOOD TO ADULTHOOD
By age three our microbiome is almost fully formed and is very similar to that of an adult, although major changes like puberty, the onset of menstruation, pregnancy, and menopause are associated with huge microbial shifts. Some of the physical changes associated with puberty, such as increased of production that can lead to acne, or more pungent body odor under the arms and in the groin, are actually the result of changes in bacteria, as different species become more or less dominant.
By the time we become senior citizens, we've lost much of our bacterial diversity, and our microbiome starts to resemble that of others in our peer group. Shifts within various microbial populations continue to occur, but as we get older, our microbiome becomes more stable, tending to revert to its previously established baseline after events like an infection or a course of antibiotics.
By age three our microbiome is almost fully formed and is very similar to that of an adult, although major changes like puberty, the onset of menstruation, pregnancy, and menopause are associated with huge microbial shifts. Some of the physical changes associated with puberty, such as increased of production that can lead to acne, or more pungent body odor under the arms and in the groin, are actually the result of changes in bacteria, as different species become more or less dominant.
By the time we become senior citizens, we've lost much of our bacterial diversity, and our microbiome starts to resemble that of others in our peer group. Shifts within various microbial populations continue to occur, but as we get older, our microbiome becomes more stable, tending to revert to its previously established baseline after events like an infection or a course of antibiotics.
Renewal of Microbiome
We start out in the womb with no microbes at all, and we eventually acquire trillions. What happens to all of those microbes when we die? interestingly, the microbes aren't recycled. They die with us, and each subsequent generation goes through its own cycle of microbial rebirth, starting from scratch and working its way up to an incredibly well-stocked microbial kingdom, well adapted to the requirements of that generation. Diversity of species is a vital part of maintaining a balanced ecosystem in the outside world, and its also crucial in the microscopic world inside us. Unfortunately, modern ire has made microbial depletion part or our legacy, with decreased diversity in each successive generation as a result of medications, our over processed diet, and our super sanitized lifestyle. Americans today have only about two-thirds as many bacterial species as native tribesmen in the Amazon who haven't been exposed to antibiotics.
While there is no perfect microbiome, some are clearly healthier than others, not withstanding the incredible variation from one to the other. The Human Microbiome Project and other research efforts like it seek to establish what the "normal" human microbiome looks like today-an important endeavor, considering the rate at which our microbial landscape is changing. The human microbiome may well be the next big frontier in medicine, providing answers to why we get sick and novel solutions for how to heal ourselves.
Microbes: The Worker Bees
Think of your body as a factory. Organs like your lungs, kidneys, and liver represent the machinery that keeps production moving: extracting oxygen, filtering blood, removing toxins, synthesizing hormones, and performing all of the other complicated tasks that keep us alive. Some of the tasks are automated, but most of these assembly lines require constant monitoring, maintenance, and adjustment.
We house the machinery, but who operates it? How does a complex process like, for example, digestion, actually happen? Who helps break down the food and determines what gets absorbed versus what gets excreted? How do we distinguish between real infection and colonization with harmless bacteria? Who tells our immune system when to rally the troops and when to ignore benign interlopers that pose no threat?
We house the machinery, but who operates it? How does a complex process like, for example, digestion, actually happen? Who helps break down the food and determines what gets absorbed versus what gets excreted? How do we distinguish between real infection and colonization with harmless bacteria? Who tells our immune system when to rally the troops and when to ignore benign interlopers that pose no threat?
Our microbes do! We've evolved over millions of years to host an incredible army of worker bee microbes that are gainfully employed assisting in all of our bodily functions. They produce substances our bodies require but can't make. They fight most of our battles for us. They even turn our genes on and off, activating those we need and dismantling those we don't. In exchange, we provide room and board.
Since we're their host and they rely on us for their survival, most of our microbes are invested in our well-being, although under certain circumstances they can tum on us and cause bad things to happen such as infection or even cancer. We can categorize our microscopic roommates into three main groups:
Since we're their host and they rely on us for their survival, most of our microbes are invested in our well-being, although under certain circumstances they can tum on us and cause bad things to happen such as infection or even cancer. We can categorize our microscopic roommates into three main groups:
- Commensal bacteria that cohabit peacefuly with us
- Symbiotic organisms (sometimes called mutualists) that help keep us healthy
- Pathogens (also known as opportunistic flora) that can do us harm
Predominant Bacteria Present in Humans
Most human bacteria fall within four general phyla, or families: Actinobacteria, Firmicutes, Proteobacteria, and Bacteroidetes-each one consisting of many different species. Different parts of the body have different microbial communities based on variations in things like oxygen content, moisture, and blood flow. Anaerobic species that don't require oxygen predominate in the gut; Staphylococci thrive on the skin, and the same Streptococci used to make Swiss cheese inhabit the mouth and upper airway. There are pathogenic (i.e. harmful) forms of all of these bacteria, but the ones that reside with us on a daily basis are mostly harmless, particularly when kept in check by adequate amounts of their symbiotic cousins.
Location |
Bacteria |
Skin |
Staphylococci, Corynebacteria |
Nose |
Staphylococci, Corynebacteria |
Mouth |
Streptococci, Lactobacilli |
Throat |
Streptococci, Neisseria |
Stomach |
Helicobacter pylori |
Small intestine |
Bifidobacteria, Enterococci |
Colon |
Bacteroides, Enterococci, Clostridia |
Urinary tract |
Staphylococci, Corynebacteria |
Vagina |
Lactic acid bacteria |
An enterotype is a classification based on ecosystems in the gut, and a way to stratify people based on the relative abundance of different species. In 2011, researcher Peer Bork described three specific enterotypes in humans: high levels of Bacteroides characterize type 1; type 2 has few Bacteroides and lots of Prevotella; and type 3 has high levels of Ruminococcus. Different enterotypes don't seem to be influenced by age, gender, or nationality, but they are profoundly affected by long-term diet. A Western diet hign in protein and animal fat is associated with Bacteroides (Type 1), while Prevotella species (type 2) dominate in those who consume more carbohydrates, especialy fiber. Different enterotypes are assoclated with predisposition to particular disease states, such as obesity and inflammation, confirming that what you eat is a powerful influencer of your overal health.
What do Gut Bacteria do?
Symbiotic organisms-the quintessential good bacteria have lots of important jobs. They help us digest food, maintain the integrity of our gut lining (part of the epithelial barrier that keeps bowel contents separate from the rest of the body), crowd out harmful bacteria, and train our immune system to distinguish between friend and foe. They also convert sugars into short-chain fatty acids (SCFAs) that intestinal cells use for energy, and they synthesize many of the enzymes, vitamins, and hormones that we can't make on our own. Food can't be properly broken down and its constituent parts can't be fully absorbed without these essential gut bacteria, which means that even if you're eating a super-healthy diet, if you don't have enough of them, you may not be able to absorb and assimilate all of the vitamins and nutrients in your food.
Most of the bacteria in your gut are anaerobic, meaning that they thrive in areas with little or no oxygen. As you travel from the top to the bottom of the intestines, the amount of bacteria increases, so the stomach and small intestine have a lot less than the colon. Some bacterial species set up shop in the intestinal lining, while others just pass through, sometimes reproducing while in transit before being excreted in the stool.
- Convert sugars to short-chain fatty acids (SCFAs) for energy
- Crowd out pathogens
- Digest food
- Help your body absorb nutrients such as calcium and iron
- Keep pH balanced
- Maintain the integrity or the gut lining
- Metabolize drugs
- Modulate genes
- Neutralize cancer-causing compounds
- Produce digestive enzymes
- Synthesize 5-complex vitamins (thiamine, folate, pyridoxine)
- Synthesize fat-soluble vitamins (vitamin K)
- Synthesize hormones
- Train the immune system to distinguish friend from foe
IMMUNE REGULATION
Digestion isn't the only process that relies on the presence of gut bacteria. Exposure to lots of different microbes-both good and bad-is essential tor priming and training your immune system, so that later on it's able to distinguish between harmless organisms that it should ignore and dangerous pathogens that it needs to respond to.
Digestion isn't the only process that relies on the presence of gut bacteria. Exposure to lots of different microbes-both good and bad-is essential tor priming and training your immune system, so that later on it's able to distinguish between harmless organisms that it should ignore and dangerous pathogens that it needs to respond to.
GENE MODULATION
We have about twenty-three thousand human genes and eight million microbial ones. Results from large-scale human microbiome studies suggest that genes from gut bacteria play an important role. They provide instructions for essential functions like carbohydrate metabolism and enzymatic detoxification instructions that are missing from our own human genome. Bacteria also help determine which diseases are expressed, turning various human genes on and off in response to the body's internal milieu, which can influence whether or not a disease that you're genetically predisposed to actually develops. Modulation of our genes by bacteria may explain why inherited diseases don't always afflict family members equally-even in identical twins, who have the same genes but different microbes.
We have about twenty-three thousand human genes and eight million microbial ones. Results from large-scale human microbiome studies suggest that genes from gut bacteria play an important role. They provide instructions for essential functions like carbohydrate metabolism and enzymatic detoxification instructions that are missing from our own human genome. Bacteria also help determine which diseases are expressed, turning various human genes on and off in response to the body's internal milieu, which can influence whether or not a disease that you're genetically predisposed to actually develops. Modulation of our genes by bacteria may explain why inherited diseases don't always afflict family members equally-even in identical twins, who have the same genes but different microbes.
You're Only as healthy as Your Gut Bacteria
Ever notice how some people never get sick when everyone else has the flu? They were probably exposed to the same virulent virus, but because they have a healthier microbiome populated with more essential microbes, they re able to crowd out the pathogens and stay healthy. Antibiotics can actually make you more susceptible to infection because they deplete essential bacterial species that can fight off viruses and dangerous bacteria. A recent study injected a bacterial protein into
mice suffering from Rotavirus-a diarrheal illness that kills half a million children each year - and successfully halted the infection. The same protein also showed efficacy against other viruses, including influenza, demonstrating the important role bacteria play in protecting against viral infection.
Microbial health is one of the factors that determines who survives potentially deadly viruses. The very young, whose microbiome is still developing, and the very old, who have fewer microbial species and less diversity, tend to be the most vulnerable. Overzealous antibiotic use also puts you at risk by stripping out the good microbes along with the bad. Of course, additional variables like coexisting medical problems and how well nourished you are play a role, too, but those factors are also tied to the health of your microbiome, so having enough good bacteria looms large as a way to protect yourself from acute as well as chronic illness.
mice suffering from Rotavirus-a diarrheal illness that kills half a million children each year - and successfully halted the infection. The same protein also showed efficacy against other viruses, including influenza, demonstrating the important role bacteria play in protecting against viral infection.
Microbial health is one of the factors that determines who survives potentially deadly viruses. The very young, whose microbiome is still developing, and the very old, who have fewer microbial species and less diversity, tend to be the most vulnerable. Overzealous antibiotic use also puts you at risk by stripping out the good microbes along with the bad. Of course, additional variables like coexisting medical problems and how well nourished you are play a role, too, but those factors are also tied to the health of your microbiome, so having enough good bacteria looms large as a way to protect yourself from acute as well as chronic illness.
Relevance of vegan gut microbiota on human and diseases
METABOLIC SYNDROME
One study indicated that the ratio of Bacteroidetes and Firmicutes was related to obesity. In obese people, the relative proportion of Bacteroidetes was decreased, and Firmicutes was increased compared with that in thin people. After eating a reduced calorie diet, the proportion of Bacteroidetes to Firmicutes was increased with weight loss in obese people. Another study was conducted with six obese people with type 2 diabetes and/or hypertension under a vegan diet for 1 month. Afterward, weight loss (average decrease 10%), improved blood glucose levels, triglycerides, total cholesterol, low-density lipoprotein cholesterol, and hemoglobin A1c were noted. A reduced Firmicutes-to-Bacteroidetes ratio (decreased abundance of Firmicutes; increased abundance of Bacteroidetes in the gut microbiota was also noted. This further indicates that a vegan diet leads to decreases in pathobionts such as Enterobacteriaceae. It caused a reduced inflammation marker, fecal lipocalin-2, which is related to glucose tolerance and lipid metabolism. Another study showed the benefits of a vegan diet on the relationship between gut microbiota and metabolic syndrome.
One study indicated that the ratio of Bacteroidetes and Firmicutes was related to obesity. In obese people, the relative proportion of Bacteroidetes was decreased, and Firmicutes was increased compared with that in thin people. After eating a reduced calorie diet, the proportion of Bacteroidetes to Firmicutes was increased with weight loss in obese people. Another study was conducted with six obese people with type 2 diabetes and/or hypertension under a vegan diet for 1 month. Afterward, weight loss (average decrease 10%), improved blood glucose levels, triglycerides, total cholesterol, low-density lipoprotein cholesterol, and hemoglobin A1c were noted. A reduced Firmicutes-to-Bacteroidetes ratio (decreased abundance of Firmicutes; increased abundance of Bacteroidetes in the gut microbiota was also noted. This further indicates that a vegan diet leads to decreases in pathobionts such as Enterobacteriaceae. It caused a reduced inflammation marker, fecal lipocalin-2, which is related to glucose tolerance and lipid metabolism. Another study showed the benefits of a vegan diet on the relationship between gut microbiota and metabolic syndrome.
CARDIOVASCULAR DISEASE
One study indicated that a vegan diet reduces the risk of cardiovascular disease (CVD) by influencing gut microbiota. The mechanism is that intestinal microbiota metabolism of dietary L-carnitine, trimethylamine abundant in red meat, produces trimethylamine-N-oxide (TMAO). TMAO, one of the metabolites of the dietary lipid phosphatidylcholine, was shown to promote atherosclerosis. Another study compared 23 long-term (>1year) vegans and vegetarians to 51 omnivores, and the fasting baseline TMAO levels were significantly lower in both the vegans and vegetarians had a reduced capacity to produce TMAO. Further analysis of fecal samples showed some bacterial genera differences in omnivores compared with vegans and vegetarians were related to plasma TMAO levels and the associated risk for atherosclerosis.
One study indicated that a vegan diet reduces the risk of cardiovascular disease (CVD) by influencing gut microbiota. The mechanism is that intestinal microbiota metabolism of dietary L-carnitine, trimethylamine abundant in red meat, produces trimethylamine-N-oxide (TMAO). TMAO, one of the metabolites of the dietary lipid phosphatidylcholine, was shown to promote atherosclerosis. Another study compared 23 long-term (>1year) vegans and vegetarians to 51 omnivores, and the fasting baseline TMAO levels were significantly lower in both the vegans and vegetarians had a reduced capacity to produce TMAO. Further analysis of fecal samples showed some bacterial genera differences in omnivores compared with vegans and vegetarians were related to plasma TMAO levels and the associated risk for atherosclerosis.
RHEUMATOID ARTHRITIS
A study was conducted with 53 rheumatoid arthritis patients who originally consumed an omnivorous diet. The study found significant changes in intestinal flora after patients shifted to a vegan diet for one year. Furthermore, fecal flora was different between patients with high improvement and low improvement. This indicates that gut profiles are associated with disease activity. Same group further studied 43 rheumatoid arthritis patients randomized into two groups consuming an uncooked vegan diet or omnivorous diet for 1 month. Significant changes in the fecal flora and decreased disease activity were noted in the vegan diet group, but not in the omnivorous diet group. This confirmed the connection between a vegan diet, fecal microbial flora, and disease activity in rheumatoid arthritis patients. A separate study reported similar results from a controlled, single-blind trial with a vegan diet.
A study was conducted with 53 rheumatoid arthritis patients who originally consumed an omnivorous diet. The study found significant changes in intestinal flora after patients shifted to a vegan diet for one year. Furthermore, fecal flora was different between patients with high improvement and low improvement. This indicates that gut profiles are associated with disease activity. Same group further studied 43 rheumatoid arthritis patients randomized into two groups consuming an uncooked vegan diet or omnivorous diet for 1 month. Significant changes in the fecal flora and decreased disease activity were noted in the vegan diet group, but not in the omnivorous diet group. This confirmed the connection between a vegan diet, fecal microbial flora, and disease activity in rheumatoid arthritis patients. A separate study reported similar results from a controlled, single-blind trial with a vegan diet.
ACUTE DIETARY EXPOSURE AND THE GUT MICROBIOME
While the core bacterial taxa are resilient to most temporary outside influences, the gut microbial community as a whole displays a high inter-individual day-to-day variability. Gut microbes are extensively and regularly purged and have the ability to double in number within one hour. Within 24-48 hours of a dietary intervention rapid changes are thought to be made to the microbial composition on a species and family level. Although the gut microbiota is not exposed to the light and dark cycle associated with the circadian rhythm, its composition and function are thought to still be affected by this cyclical ebb and flow. In humans, at least 10% of Operational Taxonomic Units (OTUs) oscillate due to the circadian rhythm. The microbiota fluctuates based on nutrient availability and the level of host-derived auto-antibodies and peptides, both of which are associated with circadian rhythm oscillations. Likewise, disrupted sleep patterns, often common in shift workers, has been found to alter the gut microbiota, increase dietary intake and promote an inflammatory response that can incite metabolic stress.
While the core bacterial taxa are resilient to most temporary outside influences, the gut microbial community as a whole displays a high inter-individual day-to-day variability. Gut microbes are extensively and regularly purged and have the ability to double in number within one hour. Within 24-48 hours of a dietary intervention rapid changes are thought to be made to the microbial composition on a species and family level. Although the gut microbiota is not exposed to the light and dark cycle associated with the circadian rhythm, its composition and function are thought to still be affected by this cyclical ebb and flow. In humans, at least 10% of Operational Taxonomic Units (OTUs) oscillate due to the circadian rhythm. The microbiota fluctuates based on nutrient availability and the level of host-derived auto-antibodies and peptides, both of which are associated with circadian rhythm oscillations. Likewise, disrupted sleep patterns, often common in shift workers, has been found to alter the gut microbiota, increase dietary intake and promote an inflammatory response that can incite metabolic stress.
THE IMPMACT OF PROBIOTICS ON MICROBIAL COMMUNITIES IS INDIVIDUALISED AND TRANSIENT
Probiotics have been defined as "live microorganisms which, when administered in adequate amounts, confer a health benefit on the host." Many probiotic bacteria are traditionally used in the fermentation of food but are now predominantly ingested by the public as supplement-like probiotic products that contain live bacteria. After consumption probiotics have the capacity to colonize and proliferate within the gastrointestinal tract thereby influencing the gut ecosystem. There is increasing popular interest in the potential benefits of probiotics. However, clinical evidence may sometimes be contradictory, mostly as a result of low study power and potential variability in the strains used between two studies. While there is limited evidence around many probiotics, some systematic reviews and meta-analyses have supported that specific strains may be effective in certain areas. Findings have indicated the benefit of probiotics in aiding the treatment of infectious- and antibiotic-associated diarrhea, insulin resistance in diabetes, and remission and maintenance of inflammatory bowel disease, amongst others. However, probiotic outcomes can be unpredictable and individualized. The ability of a probiotic strain to establish itself within the gut microbial community can be highly variable; the strain may need to compete against the host's resident microbes for substrates in tandem with resisting antimicrobial peptides, thus establishing an ecological niche displayed that colonization in the gut microbiota by probiotics occurs in highly individualized patterns, with engraftment occurring in some and not in others. Rejection is highly prevalent in healthy individuals with little evidence that probiotics have a substantive impact on the gut microbial profile besides a transient increase that rarely persist.
Probiotics have been defined as "live microorganisms which, when administered in adequate amounts, confer a health benefit on the host." Many probiotic bacteria are traditionally used in the fermentation of food but are now predominantly ingested by the public as supplement-like probiotic products that contain live bacteria. After consumption probiotics have the capacity to colonize and proliferate within the gastrointestinal tract thereby influencing the gut ecosystem. There is increasing popular interest in the potential benefits of probiotics. However, clinical evidence may sometimes be contradictory, mostly as a result of low study power and potential variability in the strains used between two studies. While there is limited evidence around many probiotics, some systematic reviews and meta-analyses have supported that specific strains may be effective in certain areas. Findings have indicated the benefit of probiotics in aiding the treatment of infectious- and antibiotic-associated diarrhea, insulin resistance in diabetes, and remission and maintenance of inflammatory bowel disease, amongst others. However, probiotic outcomes can be unpredictable and individualized. The ability of a probiotic strain to establish itself within the gut microbial community can be highly variable; the strain may need to compete against the host's resident microbes for substrates in tandem with resisting antimicrobial peptides, thus establishing an ecological niche displayed that colonization in the gut microbiota by probiotics occurs in highly individualized patterns, with engraftment occurring in some and not in others. Rejection is highly prevalent in healthy individuals with little evidence that probiotics have a substantive impact on the gut microbial profile besides a transient increase that rarely persist.
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