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Probiotics! The Gut Bacteria — The Forgotten Organ

Our intestines harbor trillion of organisms; in fact, they constitute 95% of the cells in our bodies. DNA studies indicate that the human gut houses somewhere in the order 30,000-40,000 different bacteria, and with each passing year, new physiologic roles for these organisms have been discovered. Some investigators have gone so far as to refer to the flora of the gut as “the forgotten organ” of the body.

The condition and function of the gastrointestinal tract is essential to our well-being. After the respiratory tract, the GI tract constitutes the second largest body surface area, comparable in size to a tennis court. During a normal lifetime, about 60 tons of food passes through this canal. It is estimated to harbor about 100 trillion viable bacteria. This is approximately 10 times the total number of cells in the human body. These live bacteria account for around 2-3 lbs of a body’s weight and are known as intestinal or gut flora. Viruses, fungi and protozoa can also be present, but these normally form only a minor component of the total resident population of microorganisms in healthy individuals.



The gut lining is only one cell layer thick. This allows food and nutrients, as well as toxins going out, to pass easily through this lining. This lining is protected on the stool side by a thick layer of bacteria which is actually fused to the cell wall. As we age, and as this barrier is attacked, the bacteria on the cell wall die away, allowing potentially “bad” bacteria to get close to the cell itself. When in contact with this cell barrier, the “bad” bacteria can dissolve the link between cells (usually quite cemented into place) and this allows a break in our defense.

The gut, the immune system and the brain are intimately linked. When the gut protective barrier breaks down, toxins, infectious agents, and allergens can more easily enter our bodies. Met immediately by the immune system (70% of your immune system is located in your gut), a response occurs to fight off these invaders. This response is not localized as the offending agent and the immune system can take this battle into the body. The brain is highly susceptible to these offending agents as well as the heat of the battle (inflammation) caused by this battle.

Probiotics have been found to improve health through numerous different mechanisms. Different species of bacteria predominate based on the location along the gastrointestinal tract, in part because the rate of the gut movement (motility) varies greatly from one part of the got to another.

We now know that intestinal flora plays an important role in health: stimulating the immune system, protecting the host, aiding digestion and assimilation of food.

Although the gastrointestinal tract and the composition of the individual’s gut organisms are highly individualized, some common factors have a negative effect on the gut including

  • Poor eating habits
  • Chronic physical and emotional stress
  • Lack of exercise
  • Insufficient rest
  • Frequent exposure to antibiotics
  • Different geographic location (such as a trip or a relocation)


For optimum “gut flora balance,” the beneficial bacteria, such as Lactobacilli and Bifidobacterium, should predominate, presenting a barrier to invading organisms. Saccharomyces boulardii, a probiotic yeast, has also shown promise for many indications.

The majority of the intestinal microflora in a healthy person should be good bacteria. The intestinal microflora provides protection against a broad range of pathogens as well as yeasts such as Candida albicans. The use of probiotics may be the most natural, safe and common sense approach for keeping the balance of the intestinal ecosystem.

Probiotics modulate the composition of the intestinal microflora. The survival of ingested probiotics in different parts of the gastrointestinal tract varies. This specific change may be seen for a few days after the start of consumption of the probiotic preparation, depending on the capacity and dosage. Probiotics must be ingested regularly for any health promoting properties to persist.

Some of the key mechanisms by which probiotics keep us healthy include:

  • Blockade of toxin receptor sites
  • Inhibition of the growth of the “bad” (pathogenic) bacteria
  • Inhibition of “bad” bacteria attachment to receptors
  • Enhancement of tight junction between colonic cells and prevention of impaired barrier function
  • Production of cytochrome P450- like enzymes that facilitate detoxification
  • Production of B vitamins and vitamin K
  • Interaction with the immune system
  • Creation of a physiologically challenging environment for “bad” bacteria
  • Reduction of concentrations of cancer causing enzymes


For a supplement to be considered a probiotic by most definitions, it must meet several criteria including:

  • It must contain live organisms capable of colonize in the gastrointestinal tract, meaning that, among other things, it should be acid and bile tolerant
  • It should improve the health and well-being of the host
  • Its organisms should be generally recognized as safe and not pathogenic.


Probiotics have a number of beneficial health effects in humans and animals, such as reducing lactose intolerance symptoms and enhancing the bioavailability of nutrients. Probiotics help regulate intestinal microflora and immunomodulatory properties. Probiotics also decrease the prevalence of allergies in susceptible individuals, inhibit the inflammatory responses in the gut, and have antagonistic effects against intestinal and food-borne pathogens.

Bacteria typically colonize the intestinal tract first and then reinforce the host defense systems by inducing generalized mucosal immune responses. Reports indicate that lactic acid bacteria (LAB) as Lactobacillus and Bifidobacterium and their fermented products are effective at enhancing innate and adaptive immunity, prevent gastric mucosal lesion development, alleviate allergies, and put up defense against intestinal pathogen infection.


Beneficial effects of probiotic strains, demonstrated and proposed, include the following:

  • Increased nutritional value (better digestibility, increased absorption of vitamins and minerals);
  • Promotion of intestinal lactose digestion;
  • Positive influence on intestinal and urogenital flora (antibiotics and radiation induced colitis, yeast infections and vaginitis in women);
  • Prevention and reduction of intestinal tract infections (bacteria or virus induced, Candida enteritis, Helicobacter Pylori);
  • Regulation of gut motility (constipation, irritable bowel syndrome);
  • Decreased incidence and duration of diarrhea (antibiotic associated, Clostridium difficile, travelers, and rotaviral);
  • Maintenance of protective barrier;
  • Improvement of immune system;
  • Assist in the prevention of colon cancer;
  • Reduction of catabolic products eliminated by kidney and liver;
  • Assist in the prevention of osteoporosis;
  • Better development (growth);
  • Anti-carcinogenic, anti-mutagenic and anti-allergic activities;
  • Feeling of well-being;
  • Anti-Candida properties;
  • Hepatic encephalopathy;
  • Assist in the regulation of inflammatory conditions such as Inflamatory Bowel Disease (Crohn’s disease and Ulcerative Colitis);
  • Reductions and elimination of small bowel bacterial overgrowth;
  • Relieving urinary tract infections;
  • Positive influence on autistic children;
  • Provides antagonistic environment for pathogens;
  • Blocking adhesion sites from pathogens; and
  • Inactivating enterotoxins.


General guidelines for taking your probiotics

  • Take 2 hours before or after antibiotics
  • Take on an empty stomach
  • Probiotics should be kept In the refrigerator
  • Most dosage range from 1 to 10 colony-forming units (CFU) once or twice daily.


Current research is suggesting doses upwards of 50 billion CFUs. In fact, over the past 20 years, we have seen changes in the recommendation for probiotics including:

  • Standard doses of 5 billion CFUs are too low. Current literature suggests that effective protection should be 10-25b CFU daily and in specific illnesses such as those that affect the GI tract this number may be as high as 200b CFU daily
  • Increased number of different strains within the standard Lactobacilli and Bifidobacterium genome.
  • Varying the strains of bacteria used. Research suggests that using the same probiotics over time loses effectiveness
  • More frequent dosing than once per day


As a general rule, most good quality probiotics are quite safe with few side effects, but use caution in patients with severe pancreatitis, immunocompromised people, and those with indwelling medical equipment.

If you wish to learn more, we highly recommend the websites,

Custom Probiotics, Our center has been recommending patients use these highly effective, highly diverse and potent probiotics for years. (Go to Custom Probiotics)

USProbioitics, This website has some nice summaries of the literature as well as a resource page that includes webcasts. (Go to USProbioitics)

Food Insight, This well-done educational site involves food and nutrition. (Go to Food Insight)

The International Scientific Association for Probiotics and Prebiotics, This organization’s mission is to disseminate reliable information about probiotics. (Go to

The Gut Bacteria – The Forgotten Organ



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