By Dr. Mercola
Your gastrointestinal tract is now considered one of the most complex microbial ecosystems on Earth. You may have a basic awareness that the microbes in your gut affect your digestion. But their influence extends far beyond that to your brain, heart, skin, mood, weight… and the list goes on and on.
Nearly 100 trillion bacteria, fungi, viruses, and other microorganisms compose your body's microflora, and advancing science has made it quite clear that these organisms play a major role in your health, both mental and physical.
By now most people know that our bacteria outnumber our cells 10-1, but it gets even more complex, as in addition to the bacteria there are viruses. The most common ones are bacteriophages and, get this, they actually outnumber the bacteria 10-1.1 That means you have about one quadrillion of these viruses in your gut.
All these intestinal microflora are part of your immune system and about 80 percent of it originates in your gut. Researchers have discovered that microbes of all kinds play instrumental roles in the functioning of your body. For example, beneficial bacteria, also known as probiotics, have been shown to:
- Counteract inflammation and control the growth of disease-causing bacteria
- Produce vitamins, absorb minerals, and eliminate toxins
- Control asthma and reduce risk of allergies
- Benefit your mood and mental health
- Normalize your weight
For all of these reasons, and more, I recommend a diet rich in whole, unprocessed foods along with cultured or fermented foods. If, for whatever reason you are not consuming fermented foods at least a few times a week, it's wise to consider supplementation.
A high-quality probiotic supplement can be a helpful ally to restore healthful balance to your microbiota—especially when taking antibiotics, and/or when eating processed foods, as both of these tend to decimate the colonies of friendly bacteria in your gut.
DNA Sequencing Adds to Knowledge Base About Gut Bacteria's Role in Health
A recent article in Medical News Today2 discusses some of the most recent research advances in the field of gastrointestinal health, noting that advanced DNA sequencing is now being used to shed light on the complex interactions of gut bacteria, and how such interactions affect health and the development of disease.
The article quotes Professor Gary Wu, University of Pennsylvania, Philadelphia saying:
"Using novel metagenomic approaches, scientists are at last beginning to characterize the taxonomic abundance and community relationships not only of bacteria, but also the other microbes that inhabit the gut environment.
This exciting work is bringing us one step closer to understanding the importance of microbial diversity in intestinal health and disease and could ultimately lead to new ways of diagnosing and treating gastrointestinal (GI) disease."
According to the featured article, your gut flora can be divided into the following four categories:
- Prokaryotes (bacteria and archaea)
- Bacteriophages (viruses that infect prokaryotes)
- Eukaryotic viruses (infectious agents that replicate inside living cells)
- Meiofauna (primarily fungi and protozoa)
According to Professor Wu, fungi and bacteria tend to be in competition with each other. When you decrease the fungal diversity in your gut, healthy bacterial colonization increases and vice versa. An example of this is when you develop a Candida infection following a round of antibiotics. When the antibiotics kill off healthy bacteria, the fungi are allowed to proliferate.
Through modern DNA sequencing techniques, researchers have also realized that the meiofauna in your gut can either be helpful or harmful, depending on the type of fungi or protozoa in question. Helminths and blastocystis, two types of parasites, appear to serve protective roles by suppressing inflammation in your gut, while others contribute to gastrointestinal diseases.
Even 'Bad' Microorganisms Play a Role in Maintaining Health
Research is now showing us that the complex interactions of all of these microorganisms, both bacterial and non-bacterial, can quite literally make or break your health.
Researchers are actually starting to recognize gut microbiota as one of your unappreciated "organs."3 It's even been suggested that it would be more apt to view your body as a "super organism" composed of symbiotic microorganisms, as illustrated in the video above.
The beneficial nature of this symbiotic relationship extends beyond so-called "friendly" bacteria. Even microorganisms you'd typically consider "bad" or pathogenic can play an integral role in the maintenance of health and disease prevention. As reported in the featured article:4
"The most common viruses in the gut are the bacteriophages. These rapidly-evolving viruses can outnumber bacteria by a factor of 10 to one; they infect and destroy bacterial cells and have the ability to transfer genetic material from one bacterium to another, with potentially profound implications for GI health and disease.
'There is a predator-prey relationship between bacteriophages and bacteria that may play a role in altering the bacterial microbiota in conditions such as inflammatory bowel diseases (IBD),' says Prof. Wu. 'The fact that bacteriophages induce immune responses in bacteria and may also transmit genomic material into bacteria that may alter their function makes these viruses extremely important and we need to know much more about them.'"
Gut Microbes and Cancer
Another article highlighting the importance of microbial diversity and balance was recently published by Institute of Science for Society,5 in which Dr. Eva Sirinathsinghji discusses how your microbiota influences your cancer susceptibility. She also notes the influence of your gut flora on organs such as your skin, lungs, breasts, and liver.
Gut microorganisms even appear to impact the efficacy of various cancer treatments. For example, she cites a Science study in which mice that received antibiotics three weeks before tumor inoculation did not respond well to the tumor immunotherapy given. Mice bred to not have gut microbes also responded poorly to the treatment.
Even more importantly, cancer therapies that do not work by activating your body's immune response will not work unless you have the appropriate gut microbes! Such therapies, which include certain chemotherapy agents, actually rely on gut microbes to eradicate the tumor... Gut microbiota is known to affect inflammation and metabolism, both of which are hallmarks of cancer. But DNA sequencing techniques have done much to further our understanding here as well.
"With the advent of metabolomics and deep sequencing techniques, researchers are beginning to decipher the role of specific microbes as well as specific global microbiotic profiles associated with different cancers. These discoveries are leading to new avenues of research into cancer prevention and treatment," she writes. "The relationship between our gut microbiota and cancer appears to be complex, involving both specific microbial species as well as dysregulation of the global microbiota, called dysbiosis."
Researchers have already linked certain microbes to specific cancers, such as:
- H.pylori in gastric cancer. (The International Agency for Research on Cancer defines this microbe as a carcinogen6) Interestingly, H.pylori has also been linked to a reduced risk of esophageal adenocarcinoma, demonstrating the complexity involved, and the organ-specific effects microbes can have when it comes to their impact on cancer
- Hepatitis C virus (HCV) in hepatocellular carcinoma
- Chronic Salmonella enterica infection in gallbladder cancer
- Haemophilus influenza and Candida albicans in lower respiratory tract tumors
How Can Microbes Promote or Protect Against Cancer?
So just how do microbes residing in your gut affect all these other organs? According to Dr. Sirinathsinghji, a number of different mechanisms can come into play. For example, microbes can affect cancer susceptibility by modulating your immune system and inflammation. They can also influence gene expression, and appear to have the ability to alter the stability of your genes. She also notes that:
"A failure of the intestinal barrier to limit host-microbiota interactions is also thought to be important. Anatomical separation between the host and microbes is a crucial first line of defense and is maintained through an intact epithelial lining and mucosal layer, as well as a sensing system that detects and eliminates bacteria. Consistently, ulcerative colitis, a condition that disrupts the barrier, increases the risk of colon cancers. Studies that have induced barrier failure in lab animals have also shown that carcinogens are more likely to pass through a disrupted gut lining, leading to increased tumor formation in local and distant organs."
Interestingly, Dr. Sirinathsinghji suggests it would be worth exploring fecal microbiota transplant therapy for the treatment of certain cancers. This novel procedure has been successfully used in cases of life threatening infections such as Clostridium difficile, but evidence suggests it may have many other applications as well. Cancer is one. Obesity is another.
The Microbe-Obesity Connection
Preliminary research 7 presented in 2010 actually revealed that transplanting fecal matter from healthy thin people into obese people with metabolic syndrome led to an improvement in insulin sensitivity. More recent research suggests that your diet alone can dramatically alter your microbial balance. According to Jeffrey Gordon, director of the Center for Genome Sciences and Systems Biology at Washington University in St. Louis,8 a diet high in saturated fat, and low in fruits and vegetables allows microbes that promote leanness to overtake colonies of microbes that promote obesity.
"Eating a healthy diet encourages microbes associated with leanness to quickly become incorporated into the gut," he says.
Speaking of obesity and gut bacteria, it's important to remember that when you take an antibiotic, or regularly consume foods contaminated with antibiotics (such as CAFO beef, courtesy of their use as a growth promoter in livestock), you decimate the beneficial bacteria in your GI tract. This may have a notable impact on your weight and metabolism. As noted in a recent article by Eco Child's Play,9 which discusses the antibiotic-gut microbe-obesity connection:
"Looking at how poultry is fattened up with antibiotics when it is young, a very logical hypothesis is drawn that early antibiotic use in children could have the same effect."
How Gut Bacteria 'Guide' Your Mind
The last health aspect I'll tie in here is the connection between your gut health and your mental health. This connection appears to be so strong that some propose probiotics may be the new Prozac. According to an article published the June 2013 issue of Biological Psychiatry,10 the authors suggest that even severe and chronic mental health problems, including post-traumatic stress disorder (PTSD), might be eliminated through the use of certain probiotics.
Two strains shown to have a calming influence, in part by dampening stress hormones, are Lactobacillus helveticus and Bifidobacterium longum. Others may have similar effects, although more research is needed to identify them.
"As a class of probiotic, these bacteria are capable of producing and delivering neuroactive substances such as gamma-aminobutyric acid (GABA) and serotonin, which act on the brain-gut axis. Preclinical evaluation in rodents suggests that certain psychobiotics possess antidepressant or anxiolytic activity. Effects may be mediated via the vagus nerve, spinal cord, or neuroendocrine systems," the article states.11
Using MRI scans, Dr. Emeran Mayer, a professor of medicine and psychiatry at the University of California, is also comparing the physical brain structure of thousands of volunteers, looking for connections between brain structure and the types of bacteria found in their guts. So far, he has found differences in how certain brain regions are connected, depending on the dominant species of bacteria. As reported by NPR:12 "That suggests that the specific mix of microbes in our guts might help determine what kinds of brains we have—how our brain circuits develop and how they're wired."
Optimizing Your Gut Flora May Be One of Your Most Important Disease Prevention Strategies
All of this information should really drive home the point that optimizing your gut flora is of critical importance for disease prevention, including cancer prevention. Reseeding your gut with beneficial bacteria is essential for maintaining proper balance here. As mentioned, beneficial bacteria help keep pathogenic microbes and fungi in check; preventing them from taking over. In light of this, here are my recommendations for optimizing your gut bacteria.
- Fermented foods are the best route to optimal digestive health, as long as you eat the traditionally made, unpasteurized versions. Healthy choices include lassi (an Indian yoghurt drink, traditionally enjoyed before dinner), fermented grass-fed organic milk such as kefir, various pickled fermentations of cabbage, turnips, eggplant, cucumbers, onions, squash, and carrots, and natto (fermented soy). Some of the beneficial bacteria found in fermented foods are also excellent chelators of heavy metals and pesticides, which will also have a beneficial health effect by reducing your toxic load.
Fermented vegetables are an excellent way to supply beneficial bacteria back into our gut. And, unlike some other fermented foods, they tend to be palatable, if not downright delicious, to most people. As an added bonus, they can also a great source of vitamin K2 if you ferment your own using the proper starter culture. We had samples of high-quality, fermented organic vegetables made with our specific starter culture tested, and a typical serving (about two to three ounces) contained not only 10 trillion beneficial bacteria, but it also had 500 mcg of vitamin K2, which we now know is a vital co-nutrient to both vitamin D and calcium. Most high-quality probiotics supplements will only supply you with a fraction of the beneficial bacteria found in such homemade fermented veggies, so it's your most economical route to optimal gut health as well.
- Probiotic supplement. Although I'm not a major proponent of taking many supplements (as I believe the majority of your nutrients need to come from food), probiotics is an exception if you don't eat fermented foods on a regular basis.
In addition to knowing what to add to your diet and lifestyle, it's equally important to know what to avoid, and these include:
Antibiotics, unless absolutely necessary (and when you do, make sure to reseed your gut with fermented foods and/or a probiotic supplement) Conventionally-raised meats and other animal products, as CAFO animals are routinely fed low-dose antibiotics, plus genetically engineered grains, which have also been implicated in the destruction of gut flora Processed foods (as the excessive sugars, along with otherwise "dead" nutrients, feed pathogenic bacteria) Chlorinated and/or fluoridated water Antibacterial soap Agricultural chemicals, glyphosate (Roundup) in particular