Probiotic supplementation is one of the most under discussed topics and one of the most underrated nutraceuticals for general health, with a large body of clinical research appraising their benefits. This article will discuss a number of those benefits which include: immune system reinforcement, digestion and absorption improvement, nutrient production, blood pressure and cholesterol reduction, stress damage attenuation, suppression of inflammation, prevention of intestinal infections, pregnancy protocol and allergy prevention, a decreased risk of colorectal cancer, and some dietary suggestions to optimize gut function. A new probiotic product, Güt Health™, is introduced as an option for supplementation, showing superiority over other strains in a clinical study. An introduction to prebiotics is an inclusion as a transition to the second article in this series.

Modern diets are drastically different than in the past, with modern processing techniques destroying beneficial bacteria and enzymes which would help with digestion and absorption, and many new food products that are unnatural to the human digestion system. Coupled with an increase in pollution and stress, even a strict diet may not be optimal for promoting health. Athletes especially should look into probiotic products for advantageous recovery and improved strength and performance; however they can be extremely beneficial to anyone for general health.

An Introduction to the Intestinal Mucosal Immune System

As bacteria enter the stomach, most are destroyed because of the extremely low pH. Those that do survive pass through the pyloric sphincter to the duodenum. They are then attacked by bile salts and pancreatic secretions. Surviving through this point means they are able to increase in number as they enter the colon. From mouth to anus, the transit time for bacteria is about 55 to 72 hours, with the majority (54 to 56 hours) in the colon. They are able to colonize if they adhere to the mucus layer (73). Bacteria in the gastrointestinal tract alone amount to trillions, and can be generally divided into two categories: indigenous, and pathogenic. The average intestine holds an astonishing 1.2 kilograms (~2.6 pounds) of bacteria (2). Indigenous bacteria coexist in symbiosis with us providing many benefits, and we simply could not survive without them. Pathogenic bacteria can cause illness if not controlled by indigenous bacteria. If the balance is disrupted, many adverse effects can occur. In other words, the intestinal tract is inhabited with many bacteria, some being beneficial to the host and some harmful, forcing immune responses to maintain homeostasis. Proliferation of pathogenic bacteria leads to symptoms caused by the secretion of toxins from these bacteria.

Most estimates suggest that at least 500 species flourish in the intestine, all interacting and with different functions. No two people have the same population ratios, and diet and environment are large influential factors on this. Because the intestine is the primary interaction between outside pathogens and the immune system and the most active immune organ housing about 60% of total immunoglobulins and lymphocytes, keeping it optimized will prevent many illnesses and provide additional benefits. It is where the mucosal immune system constantly processes food and antigens and is subject to change from each nutrient or microbe it encounters. If the immune system isn't fed by stimulating nutrients or beneficial bacteria, it becomes susceptible to the harmful bacteria trying to penetrate it by the alteration of some of its key fighting functions. The mucosal immune system is unique because it is independent of the systemic immune system, and probiotics have an influential effect on both (72). Bacteria may even have an effect on overall human growth, thus an inadequate diet may stunt growth this in this manner (74). The lactobacilli and bifidobacteria species are thought to be the most abundant and influential on health, and therefore most of the following information evaluates data on these strains.

Consuming foods containing pathogenic microbes or their toxins can cause gastroenteritis. Symptoms that accompany include vomiting, nausea, diarrhea, abdominal cramps, etc. Because many pathogenic bacteria inhabit the gut of animals too, poor slaughter practices of meat and poultry can lead to infection, even if the rest of the transportation and handling of the animal is clean. Vegetables may also become a danger from the use of animal manure as fertilizer. It is evident that different strains of bacteria have different effects on the body. For instance, Escherichia coli, Sihigella spp., salmonellae, and yersinae cause bacterial multiplication within enterocytes or colonocytes. Enteropathogenic and enterohemorrhagic strains of Escherichia coli, and shigellae are cytotoxic, causing direct cell damage. Toxigenic bacteria produce enterotoxins which alter salt and water secretion, include Vibrio cholera, and some shigellae. Another strain of E. coli can bind to the colonic mucosa which can establish infections in the gastrointestinal tract while avoiding detection from an immune system and indigenous microflora response (4).

Probiotic Basics

Probiotics are considered to be a "food or drug containing live microbes that confer positive physiologic changes in the host animal" (10). Most are dietary supplements that contain bacteria or yeast, but the most common are lactic acid bacteria. Currently studied, the beneficial microbial flora to the human intestinal tract include species from the genera: Lactobacillus, Bifidobacterium, and Enterococcus. The subnames of these species are: Lactobacillus acidophilus, Lactobacillus johnsonii, Lactobacillus gasseri, Lactobacillus casei, Lactobacillus rhamnosus, Lactobacillus plantarum, Bifidobacterium longum, Bifidobacterium breve, Bifidobacterium bifidum, Bifidobacterium infantis, Enterococcus faecalis, and Enterocuccus faecium (11, 12). Some of the Bifidobacterium species are only present in non human animal intestinal tracts, and may be present in animal probiotic products, including the species: Bifidobacterium thermophilum, and Bifidobacterium pseudolongum (13). Not all probiotic microbes exist in the intestinal tract, so their influence on enteric microbial balance is probably small. These species include: Lactobacillus bulgaricus, Streptococcus thermophilus, Leuconostoc, and Lactococcus (14).