Probiotics and prebiotics

A healthy gastrointestinal tract with adequate mucus production and appropriate bacterial colonization prevents the overgrowth of pathogenic bacteria, modulates disease processes, and prevents widespread inflammatory disorders.

Probiotics, literally meaning “for life,” are microorganisms proven to exert health-promoting influences in humans and animals. For example, Metchnikoff discovered and promoted Lactobacillus bulgaricus as an aid in souring milk products to extend their shelf life. Tissier demonstrated that Bifidobacteria were helpful in treating infant diarrhea. 

In 1994, the World Health Organization deemed probiotics to be the next-most important immune defense system when commonly prescribed antibiotics are rendered useless by antibiotic resistance. The use of probiotics in antibiotic resistance is termed microbial interference therapy. 

Probiotics are naturally found in the mouth, lower intestine and vagina. Probiotic microflora display numerous health benefits beyond providing basic nutritional value. They cooperatively maintain a delicate balance between the gastrointestinal tract and immune system. When this balance is disrupted, disease and inflammation result.

Mechanisms of action of probiotics

  • Production of inhibitory substances, aka inhibition of “bad” bacteria

  • Blocking of adhesion site: PB and pathogenic bacteria are in a competition.

  • Competition for nutrients.

  • Stimulation of immunity: specific cell wall components of cell or all cell layers act as adjuvants and increase humoral immune response.

  • Degradation of toxin receptors

  • Most probiotics are related to the lactobacillus and bifidobacterium genera

  • Adhere to cells; 

  • Exclude or reduce pathogenic adherence; 

  • Persist and multiply; 

  • Produce acids, peroxide, and bacteriocins 

  • antagonistic to pathogen growth; 

  • To be safe, noninvasive, noncarcinogenic and 

  • nonpathogenic; 

  • Coaggregate to form a normal balanced flora. 

Effects of probiotics on health 

  • Managing lactose intolerance

  • Improving immune system

  • Prevention of colon cancer

  • Reduction of cholesterol and plasma triglycerol concentration

  • Lowering BP

  • Reducing inflammation

  • Reducing allergic symptoms

  • Beneficial effects on mineral metabolism, particularly bone density and stability

Probiotics effect

  • Increased nutritional value (better digestibility, increased bioavailability of minerals and vitamins) 

  • Promotion of intestinal lactose digestion (reducing symptoms of lactose intolerance and malabsorption) 

  • Promotion recovery from diarrhea (rotavirus, travelers) 

  • Positive influence on intestinal flora (antibiotics or radiation induced colitis) 

  • Inhibition of pathogen growth and translocation

  • Colonization of the gut with appropriate microflora contributes to its ability to function normally. Commensal microflora byproducts contribute to the health of the intestinal tract and in- clude short-chain fatty acids (SCFAs), polyamines, vitamins, antioxidants, and amino acids. 

  • For example, the SCFA butyric acid, derived from carbohydrate fermentation, provides the main fuel for colonocytes in the large intestine. In addition, Lactobacillus species can prevent food decay, preserve antioxidants and vitamins, remove toxic food components, and prevent pathogenesis of Entero- bacteriaceae, S. aureus, and Enterococci found in fermented foods. 

Probiotics and the immune system

Probiotics modulate not only the endogenous flora of the GI tract, but also the immune system. Lactobacilli augment both cellular and humoral immunity. Lactic acid producing bacteria stimulate various aspects of the immune system, including phagocytic function of macrophages, natural killer cells, monocytes, and neutrophils. The interactions of commensal bacteria and probiotics with the surface of APCs, mainly through TLR, in most studies result in the downregulation of pro-inflammatory genes that are linked to inflammatory signaling pathways, whereas other anti-inflammatory genes are upregulated. The probiotic-mediated increase in TGF-β and IL-10 expression can help to explain the immunotolerance process that is mediated by these microorganisms. 

Probiotics and their role in inflammation

Probiotics exert their actions through interaction with intestinal cells, which in turn modify the expression of many genes that are mainly related to the gut-associated immune system. Although the specific actions are de- pendent on the particular bacteria and strains, probiotics mainly induce a tolerogenic response to external antigens by interacting with TLR and down-regulating the expression of NF-κB and pro-inflammatory cytokines. 


To qualify as a beneficial microflora, the following criteria must be met: 

  1. It must be acid and bile resistant; 

  2. It must be metabolically active in the GI tract; 

  3. It must be able to adhere to the GI tract; 

  4. It must possess antimicrobial activity toward pathogenic bacteria; 

  5. It must reduce colon pH. 

Probiotics effect

  • Prevention of intestinal tract infections (bacteria or virus induced, Candida enteritis, Helicobacter pylori ulcus/ neoplasia) 

  • Regulation of gut motility (constipation, irritable bowel syndrome) 

  • Enhancing specific and nonspecific immune response system 

  • Stimulation of gastrointestinal immunity

  • Improved urogenital health

  • Prevention of cancer and suppressing tumors

  • Detoxification of carcinogens

  • Reduction of catabolic products eliminated by kidney and liver

  • Prevention of arteriosclerosis (reduction of serum cholesterol)

  • Prevention of osteoporosis

  • Better development (growth)

  • Improved well-being 

  • Synthesized nutrients (folic acid, niacin, riboflavin,  vit B6 and 12

  • Increasing nutrient bioavailability

  • Decreasing prevalence of allergy in susceptible individuals * Decreasing lower serum cholesterol concentrations

  • Reduction of blood pressure in hypertensives 

UC and probiotics (animal studies)

Although studies evaluating the mechanism of action of probiotics in IBD are heterogeneous because of the different methodological approaches, basically probiotics lead to the downregulation of a number of proinflammatory genes and the upregulation of others, e.g., mucin genes, which can help explain the beneficial effects of probiotics in decreasing the activity of these gut diseases. 

Probiotics and liver

Endotoxemia is considered a major risk for inducing liver inflammation in nonalcoholic ste- atohepatitis (NASH) and nonalcoholic fatty liver disease (NAFLD) in humans. NASH and NAFLD are associated with increased gut permeability in humans. Cani et al(2009) demonstrated the alteration of gut- barrier function in genetic models of obesity. Overall, these studies strongly suggest a direct link between the gut microbiota, the gut barrier, and hepatic changes. 

Colon and other cancer treatment

PB plays an important role in retarding colon carcinogenesis by possibly influencing metabolic, immunologic and protective function of colon

Safety of probiotics

Needs to be recognized by GRAS, generally recognized as safe by FDA


Different brands of probiotics can contain anywhere from one to 10 billion colony-forming units or CFUs. To maintain a healthy digestive tract, a probiotic with one to two million CFUs is recommended. However, if you are taking antibiotics, or if you have symptoms of a bacterial imbalance such as diarrhea, you can take a probiotic with up to 10 billion CFUs until the problem clears up. Probiotic brands differ as to how many CFUs they contain. You should not take five probiotic capsules containing two billion CFUs because this may not give you the proper balance between strains. If you’re having a problem and need more CFUs, you should always purchase a brand that contains that many in one capsule. To maintain microorganism balance, take a probiotic of one to two million CFUs daily or every other day. To correct a problem, probiotics containing 10 million CFUs can be taken daily for up to two weeks.


Prebiotics are non digestible food ingredients that when consumed in sufficient amounts, selectively stimulate the growth and/or activity of one or a limited number of microbes in the colon, resulting in health benefits. Prebiotics currently in use are mainly carbohydrates of low digestibility that are typically naturally present in foodstuffs and include mannooligosaccha- rides (MOS), pectic-oligosaccharides (POS), xylooligosaccharides (XOS), galactooligosaccharides (GOS) 

  • Most prebiotics  are obtained from extraction from plants.

  • They are found in fruits, vegetables, milk and honey

  • Inulin increases the phagocytic capacity of macrophages and the production of secretory IgA, 

Sources and production of prebiotics

  • Breast milk, onions, leeks, garlic, soybeans, banana, barley, corn, oats, potato, lentils, asparagus, artichoke, tomatoes

  • Inulin is obtained from chicory

Diverticular disease

Diverticular disease is more often categorized as a civilization disease that affects both women and men, especially at an old age. The pathophysiology remains complex and arises from the interaction between dietary fiber intake, bowel motility and mucosal changes in the colon. Obesity, smoking, low physical activity, low-fiber diet (poor in vegetables, fruit, whole grain products, seeds and nuts) are among factors that increase the risk for developing diverticular disease. Additionally, the colonic outpouchings may be influenced by involutional changes of the gastrointestinal tract. Therefore, the fiber rich diet (25-40 g/day) plays an important role in prevention, as well as nonpharmacological treatment of uncomplicated diverticular disease. The successful goal of the therapy can be achieved by well-balanced diet or fiber supplements intake. Research indicate the effectiveness of probiotics in dietary management during the remission process. Moreover, drinking of appropriate water amount and excluding from the diet products decreasing colonic transit time – should be also applied.