We actually have three to four pounds of friendly bacterial critters lining our GI tract, helping us to digest difficult proteins and activating a healthy immune system. While it might make you feel a little uneasy, we have a natural symbiosis with these organisms, depending on them for normal body functioning.
Prebiotics are the food that the good bacteria eat in our gut. The fancy words for these compounds are fructans, fructooligosaccharides, and arabinogalactans. These substances are found in plant material, like in the skin of an apple, steel cut oats, onions, garlic and even in the flesh of a kiwi or a plantain. When digested, it not only feeds the healthy bacteria, but healthy small chain fatty acids (aka SCFA's) are produced as a byproduct, which are used by our intestinal cells as fuel.
It may also help support natural immune defenses of the gut like the SIgA, which is the primary immune defense of the gut. Low SIgA can lead to allergies, and can be further complicated by cortisol from stress.
Probiotics are the specific strains of healthy bacteria. These produce immune compounds that help communicate to our body and activate the right balance of innate and learned immune defenses.
Without a balance of healthy bacteria, Imbalances in our immune system may result, with an over-reliance on "learned defense" - possibly tipping the balance in favor of autoimmune conditions where individuals begin attacking their own healthy tissues.
I typically recommend that you look for at least 10 billion CFU in probiotic supplements. Some research has clinical results appearing at as high of doses at 60 billion CFU. To be honest, researchers really have yet to sift out what strains are best effective at what dosages, but side effects are typically mild such as gassiness, bloating, or unexpected increase in number of bowel movements.
Probiotics do not necessarily have to be consumed in supplement form. Sauerkraut, yogurt, and fermented soy are some examples of natural sources. Some people are turning to making their own fermented foods at home.
Causes of an imbalance include antibiotic usage, and a food plan high in refined sugars and simple carbohydrates.
Consequences of Bacterial Imbalance
Disrupting the integrity of the gastrointestinal barrier may lead to the development of food allergies and sensitivities.
In the case of Hashimoto's thyroiditis, it is believed that gluten, even in the case of a negative bloodtest, can aggravate the thyroid even in the absence of negative blood testing. This is because most tests simply measure transglutaminase...which is just one of a handful of markers that may be positive. Biopsies of the lining may also require up to 50% atrophy or withering away of the absorptive lining to show a positive test result. Unfortunately, many doctors will not dig further into testing because it simply does not change the treatment plan they will offer.
As further testing is not part of the "standard of care" in medicine so sometimes patients are left with more questions than answers. Further testing doesn't really change the treatment and the condition becomes a "watch and wait" as medication dosages are adjusted, further biopsies are taken, other tests administered, and surgical/ablation options are considered.
It also doesn't help that food sensitivities are viewed by many as just an "intolerance" than a "legitimate" contributor to chronic disease.
Any unknown food sensitivity will likely lead to an imbalance of healthy bacteria. When healthy bacteria are not present, harmful bacteria and yeasts begin taking up real-estate in the gut, releasing toxins internally that have been associated with such disorders as chronic fatigue syndrome (Maes M, J Affect Dis 2007; 99:237-240) or even seemingly indirect disorders like chronic urinary tract infections, frequent urination, fatigue, and even mood swings.
New research also suggests that these toxins, even at low levels, can initiate obesity and insulin resistance over time (Cani PD, et al. Diabetes, 2007; 56:1761-1772; DiBaise JK, et al, Mayo Clin Proc 2008; 83: 460-469; Kalliomaki M, et al Am J Clin Nutr 2008; 87:534-538).
Prebiotics and Probiotics, taken together have been characterized as Synbiotics. This reflects the symbiotic relationship our bodies have not only with the food we eat and the phytochemicals they provide for healthy gene messages, but to the physical relationships between us and trillions of our bacterial friends. In fact, there's more cells of bacteria in our gut than there are cells comprising our human body.
It's interesting to see how probiotics are being commercialized. Companies are taking advantage advantage of labeling, adding a few probiotics, and suddently calling it a health food, when in reality, it may not be much more than "window-washing" for an otherwise unhealthy product. Dannon's Activia yogurt for example, has been under considerable controversy with its health claims for "Bifidus regularis".
So imbalances in good bacteria can lead to general gastrointestinal distress, poor digestion, poor detoxification, immune imbalances, and may contribute to complications with insulin resistance and obesity affecting some 70% of Americans.