Trillions of bacteria are hostile and can cause disease, while many others are friendly and have established a symbiotic, mutually beneficial relationship with us over the millennia. These friendly bacteria have also been referred to as "probiotics" and are being used increasingly by mainstream clinicians for both preventive and therapeutic purposes. The literal translation of the word probiotic is "for life." A growing number of studies suggest that part of what determines how the human body functions may be not only our own genes, but also the genes of the trillions of microorganisms that reside on and in our bodies.
Bacteria Keep Us Alive
The genomes of the bacteria and viruses of the human gut alone are thought to encode 3.3 million genes. "The genetic richness and complexity of the bugs we carry is much richer than our own," says Jayne Danska, an immunologist at the Hospital for Sick Children Research Institute in Ontario, Canada. "They serve as a buffer and interpreter of our environment. We are chimeric organisms."
Problems ranging from autoimmune disease to clinical depression and simple obesity may in fact be linked to immune dysfunction that begins with a "failure to communicate" in the human gut, scientists say. Health care of the future may include personalized diagnosis of an individual's "microbiome" to determine what prebiotics or probiotics are needed to provide balance.
A role for gut microbes in gastrointestinal function has been well documented since researchers first described differences in the fecal bacteria of people with inflammatory bowel disease The molecular mechanisms responsible for the gut microbiome's impact on metabolism and diseases throughout the body remain largely unknown. However, researchers are beginning to decipher how the microorganisms of the human intestinal tract influence biological functions beyond the gut and play a role in immunological, metabolic, and neurological diseases.
"Asked about their immune system, most people might think of white blood cells, lymph glands or vaccines," said Dr. Natalia Shulzhenko, author of a new report in Clinical Reviews in Allergy and Immunology, and assistant professor and physician in the OSU Department of Biomedical Sciences. "They would be surprised that's not where most of the action is. Our intestines contain more immune cells than the entire rest of our body.
Early research on microbiota focused largely on the commensal bacteria that reside in the human gut. Commensal gut bacteria supply nutrients, help metabolize indigestible compounds, and defend against colonization by nonnative opportunistic pathogens.
The Good and The Bad
But the distinction between "good" microbes that aid health and "bad" pathogenic microbes that cause disease has become blurred in recent years. Researchers have shown that under certain conditions, some types of normal gut bacteria can trigger disease. Sarkis Mazmanian, a microbiologist at the California Institute of Technology, dubbed these elements "pathobionts"; the term "pathogens," in contrast, refers to opportunistic microbes that are not normally part of the gut microbial community.
Disturbances to the microbial equilibrium of the gut may mean that some microbes become overrepresented while others are diminished. "It's like a garden--you're less likely to have weeds growing if you have lush vegetation, but without this vegetation the weeds can potentially take over," Mazmanian says. When the gut moves toward a state of microbial imbalance, normally benign gut microbes may begin to induce inflammation and trigger disease throughout the body, even in the nervous system.
Researchers have long postulated that gut bacteria influence brain function. A century ago, Russian embryologist Elie Metchnikoff surmised that a healthy colonic microbial community could help combat senility and that the friendly bacterial strains found in sour milk and yogurt would increase a person's longevity.
In 2011 Mazmanian and colleagues reported that changes in gut microbial composition might have far-ranging effects that extend to the brain.
Mazmanian says, the microorganisms that colonize the human gut don't leave the intestine, but the immune cells that contact them do. He explains that, although 70% of the immune cells in the body at any one time can be found in the intestine, they circulate throughout the body, and the microbiota of the gut environment help determine how immune cells will behave elsewhere. He gives an example: "If T-cells, while in the gut, are programmed by the microbiota to have anti-inflammatory properties, then they may suppress inflammation even after they leave the gut."
Proteins, carbohydrates, and other molecules shed by microbes also leave the gut and may play a role in signaling disease. Studies have shown these bacterial metabolites are pervasive throughout the body--in the lungs, amniotic fluid, and breast milk, all tissues once thought to be free of microbial communities.
Other researchers have suggested a link between the gut--brain axis and neuropsychiatric disorders such as autism, depression, and eating disorders. The gut contains microorganisms that share a structural similarity with the neuropeptides involved in regulating behavior, mood, and emotion--a phenomenon known as molecular mimicry. The body can't tell the difference between the structure of these mimics and its own cells, so antibodies could end up attacking both, potentially altering the physiology of the gut--brain axis.
The Power of Probiotics
Probiotics offset other intestinal bacteria that produce putrefactive and carcinogenic toxins. If harmful bacteria dominate the intestines, essential vitamins and enzymes are not produced and the level of harmful substances rises leading to cancer, liver and kidney disease, hypertension, arteriosclerosis and abnormal immunity. Harmful bacteria can proliferate under many different circumstances including peristalsis disorders, surgical operations of the stomach or small intestine, liver or kidney diseases, pernicious anaemia, cancer, radiation or antibiotic therapies, chemotherapy, immune disorders, emotional stress, poor diets and aging
The best known of the probiotics are the Lactobacilli, a number of species of which (acidophilus, bulgaricus, casei and sporogenes) reside in the human intestine in a symbiotic relationship with each other and with other microorganisms (the friendly Streptococci, E. coli and Bifidobacteria). Lactobacilli are essential for maintaining gut microfloral health, but the overall balance of the various microorganisms in the gut is what is most important.
Another probiotic which has recently generated a great deal of interest is the friendly yeast known as Saccharomyces boulardii, an organism that belongs to the Brewer's Yeast family, not the Candida albicans group. S. boulardii is not a permanent resident of the intestine but, taken orally, it produces lactic acid and some B vitamins, and has an overall immune enhancing effect. In fact, it has been used therapeutically to fight candida infections.
6 SURPRISING FACTS ABOUT MICROBES IN YOUR GUT
1. What's in Your Gut May Affect the Size of Your Gut
Need to lose weight? Why not try a gut bacteria transplant?
New research published in the journal Science suggests that the microbes in your gut may play a role in obesity.
2. Probiotics May Treat Anxiety and Depression
Scientists have been exploring the connection between gut bacteria and chemicals in the brain for years. New research adds more weight to the theory that researchers call "the microbiome--gut--brain axis."
Research published in Proceedings of the National Academy of Science shows that mice fed the bacterium Lactobacillus rhamnosus showed fewer symptoms of anxiety and depression. Researchers theorize that this is because L. rhamnosus acts on the central gamma-aminobutyric acid (GABA) system, which helps regulate emotional behavior.
L. rhamnosus, which is available as a commercial probiotic supplement, has also been linked to the prevention of diarrhea, atopic dermatitis, and respiratory tract infections.
3. The More Bacteria the Better
While bacteria on the outside of your body can cause serious infections, the bacteria inside your body can protect against it. Studies have shown that animals without gut bacteria are more susceptible to serious infections.
Bacteria found naturally inside your gut have a protective barrier effect against other living organisms that enter your body. They help the body prevent harmful bacteria from rapidly growing in your stomach, which could spell disaster for your bowels.
To do this, they develop a give-and-take relationship with your body.
"The host actively provides a nutrient that the bacterium needs, and the bacterium actively indicates how much it needs to the host," according to research published in The Lancet.
4. Gut Bacteria Pass from Mother to Child in Breast Milk
It's common knowledge that a mother's milk can help beef up a baby's immune system. New research indicates that the protective effects of gut bacteria can be transferred from mother to baby during breastfeeding.
Work published in Environmental Microbiology shows that important gut bacteria travels from mother to child through breast milk to colonize a child's own gut, helping his or her immune system to mature.
5. Lack of Gut Diversity Is Linked to Allergies
Too few bacteria in the gut can throw the immune system off balance and make it go haywire with hay fever.
Researchers in Copenhagen reviewed the medical records and stool samples of 411 infants. They found that those who didn't have diverse colonies of gut bacteria were more likely to develop allergies.
But before you throw your gut bacteria a proliferation party, know that they aren't always beneficial.
6. Gut Bacteria Can Hurt Your Liver
Your liver gets 70 percent of its blood flow from your intestines, so it's natural they would share more than just oxygenated blood.
Italian researchers found that between 20 and 75 percent of patients with chronic fatty liver disease--the kind not associated with alcoholism--also had an overgrowth of gut bacteria. Some believe that the transfer of gut bacteria to the liver could be responsible for chronic liver disease.
How Do Probiotics Work
Probiotics work in many different ways by their production of antimicrobial substances (organic acids, hydrogen peroxide, and bacteriocins) that inhibit pathogen adhesion and degrade toxins produced by microbial invaders. Probiotics resist colonization by competing for binding sites as well as for nutrients with pathogens. In other words, they crowd out pathogens like candida and harmful E. Coli.
Probiotics secrete various proteins that stimulate the immune system both locally and throughout the body, boost intestinal brush border enzyme activity and increase secretory-IgA (a family of antibodies lining mucous membranes). Enzymes like lactase, sucrase, maltase, alpha-glucosidase, and alkaline phosphatase are enhanced by probiotics. Cholesterol and triglyceride blood levels are metabolized and lowered by healthy probiotic populations. Probiotics are able to resist translocation, defined as the passage of pathogens from the GI tract to extraintestinal sites such as the mesenteric lymph node (MLN), spleen, liver, kidneys, and blood.
Benefits of Probiotics
The following are the most well documented benefits of taking probiotics regularly:
- Weaken antibiotic resistant bacterial strains, attack new types of pathogens (supergerms) and infections in immuno-compromised people requiring treatment (i.e. resist opportunistic infections like candidiasis)
- Manufacture B vitamins (biotin, B3, B5, B6, folic acid, B12) and vitamin K
- Secrete lactase, an enzyme required to break down lactose in milk
- Act as anti-cancer factors (especially for bladder and bowel) by inhibiting bacteria that convert nitrates into nitrites
- Inhibit bacteria that secrete carcinogens
- Function as natural antibiotics against unfriendly bacteria, viruses and yeast like Candida albicans
- Enhance bowel function and elimination; prevent constipation
- Reverse diarrhea conditions (Crohn's disease, AIDS, Traveller's)
- Reduce or eliminate bloating, gas, straining and abdominal pain due to any cause
- Prevent skin problems, especially acne and other skin infections. (FYI - most chronic acne conditions in adults are often improved or eliminated by a good bowel flora balance).
- Protect against the adverse effects of radiation and pollutants
- Reduce blood levels of cholesterol and triglycerides
- Fight stress and food cravings and thereby prevent or reverse obesity
- Help eliminate bad breath
- Optimize sex hormone levels, enhance fertility and prevent osteoporosis
- Produce lactic acid, improve the digestibility of foods
- Oppose putrefactive bacteria like bacteroides associated with a meat-rich diet
- Treat eczema, psoriasis, ulcerative colitis, Crohn's Disease, irritable bowel syndrome, all cancers, gastritis, duodenitis, diverticulitis, food allergies, lactose intolerance, environmental allergies, urinary tract infections, vaginitis, other chronic infections (TB, AIDS, Herpes, venereal diseases) and autoimmune diseases (e.g. rheumatoid arthritis, polymyalgia rheumatica, ankylosing spondylitis, psoriasis, lupus, alopecia areata, scleroderma, thyroiditis, etc.)
Cultured dairy products like yogurt, acidophilus milk, buttermilk, sour cream, cottage cheese and kefir are the best known food sources of friendly bacteria. Equally effective probiotic food sources include cultured/fermented vegetables (cabbage, turnips, eggplant, cucumbers, onions, squash, and carrots). Other, lesser known or used food sources of probiotics are sauerkraut and sourdough breads. Ideally, one could get a good supply of probiotics from one or more of these diverse foodstuffs. If dietary sources are not easily available, supplemental probiotic powders and capsules are good alternatives. Choose a brand that has at least 3 different strains of friendly bacteria and between 6 -- 15 billion live organisms.
Karen Foster is a holistic nutritionist, avid blogger, with five kids and an active lifestyle that keeps her in pursuit of the healthiest path towards a life of balance.