1. Probiotics are live microorganisms that have been shown to have a beneficial health effect on the body.

No. Probiotics are micorganisms that can consist of various strains of bacteria such as lactobacillus, acidopilus, bifidobacter etc., but also may include probiotic yeast such as saccharomyces boulardii. They are always live microorganisms and ones that are intended to provide healthy benefits when taken orally.

No. Not all live microorganisms or live culture bacteria like those in fermented foods or yogurt have been shown to have a health benefit to qualify as probiotics. It the microorganisms are dead or killed during processing or do not have a health benefit then they are not effective as a probiotic.

Some of the major effects of probiotics are known but not all the beneficial effects are known or understood. However, in general, probiotics are a collection of live microorganisms, that when they are ingested, multiply and  colonize the gut where they produce a variety of beneficial effects. Their health benefits include not only the gut but throughout the body, likely through circulating immune factors. An example includes a recent study that showed that probiotics decreased duration of the common cold.

All of us have more than a trillion microbes and over a 1000 different types of bacteria in our body. Each of our collection of microbes or flora is as unique as our fingerprint. Our unique gut flora "fingerprint" is extremely stable over our lifetime, becoming established early in childhood and generally remaining unchanged until old age unless disrupted by antibiotics. Keeping a stable healthy gut flora is becoming more difficult because of overuse of antibiotics inappropriately for viral infections, in foods or more powerful antibiotics being given for infections due to increasingly resistant bacteria.

The function of the appendix is believed to be to store microbes to reestablish our normal gut flora. Though there are some contradictory studies, most studies seem to show a higher incidence of Crohn’s disease and colitis in people who have had an appendectomy. Though the exact cause or causes of inflammatory bowel diseases are not known it now believed that altered gut flora and genetics are critical to their development.

Probiotics decrease inflammation in the gut, can help provide nutrition needed for healthy gut lining cells, synthesize vitamins such as the B vitamins biotin and folate, and can break down certain cancer causing chemicals (carcinogens) in our diet.

Possibly. Probiotics have been shown to decrease responses to allergens, both food allergens and pollen allergens

Probiotics produce natural antibiotics (acidophilus produces antibiotic acidophilin) and can reduce or prevent infections in the gut. Probiotics are commonly prescribed now to prevent or treat Clostridium difficile bacterial infection, a common complication of antibiotic therapy.

Probiotics reduce, prevent and/or heal leaky gut. They enhance the gut barrier function.

Probiotics have been shown to reduce the toxicity of gluten. Studies have shown a benefit of probiotic bacteria that are added to gluten containing breads. They may be especially beneficial in those with Celiac disease, potentially protecting against cross-contamination exposure. Probiotics may help heal leaky gut caused by gluten even in those without Celiac disease.

Daily there is new evidence of the health benefits of probiotics and/or new diseases being linked to altered gut flora (dysbiosis). Just a few diseases or conditions linked to altered gut flora or benefited by taking probiotics include dental cavities, Crohn’s disease, ulcerative colitis, Celiac disease, diabetes, heart disease, allergies, intestinal infections, yeast infections (especially vaginal), colds and respiratory infections, rheumatologic conditions, multiple sclerosis, autism and cancer.

Many if not most of us need probiotics at some point, especially after a course of antibiotics. Individuals both children and adults who have been given a lot of antibiotics or very potent antibiotics often get an imbalance of good and bad bacteria in their digestive tract. Those who no longer have their appendix also may have difficulty restoring the normal balance since one of the jobs of the appendix is to store an individuals normal gut flora. Those who have IBS or IBD (colitis or Crohn's disease) and celiac disease often benefit from probiotics. Imbalances can be presumed when there are symptoms suggestive of altered gut flora (bloating, gas, diarrhea) or risk factors (recent antibiotics, IBD, IBS) or specific testing can be done. Most laboratories do not specifically test for good bacteria and bad bacteria levels. They will test for specific bacterial infections like salmonella, shigella, listeria, camplobacter, invasive E. coli etc. and parasites such as giardia. Genova Laboratories does test for levels of good and bad bacteria.

Inthis example there is little to no growth of the beneficial "good" probiotic bacteria and overgrowth of the "bad" potential pathogenic (disease causing) bacteria. A combination of antibiotic directed at killing the bad bacteria and a probiotic to restore the good bacteria would be helpful in this instance. Some natural remedies are reported to help as well.