**2.1 Probiotic selection**

Requirements that a probiotic organism should meet are the following: resistance to gastric acidity, resistance to bile and pancreatic enzymes; adherence to intestinal mucosa cells; colonization capacity; keep itself alive for a long time during transportation, storage, so they can effectively colonize the host; production of antimicrobial substances against pathogenic bacteria and absence of translocation (Capriles et al., 2005).

For a microorganism be used as a probiotic, it is necessary its isolation, characterization and assessments which will prove its probiotic efficiency (Figure 1).

Fig. 1. Probiotic selection chart.

Firstly, a microorganism source have to be selected (for example: digestive tract of health animals or other niches such as flowers, decomposing fruits). Then, the microorganisms which are intended to work with are isolated and identified through selective culture media.

used as a therapeutic strategy to improve human health. The precise mechanisms influencing the crosstalk between the microbe and the host are still unclear but there are evidences suggesting that bacteria in the gut could modulate the functioning of the immune

Requirements that a probiotic organism should meet are the following: resistance to gastric acidity, resistance to bile and pancreatic enzymes; adherence to intestinal mucosa cells; colonization capacity; keep itself alive for a long time during transportation, storage, so they can effectively colonize the host; production of antimicrobial substances against pathogenic

For a microorganism be used as a probiotic, it is necessary its isolation, characterization and

Firstly, a microorganism source have to be selected (for example: digestive tract of health animals or other niches such as flowers, decomposing fruits). Then, the microorganisms which are intended to work with are isolated and identified through selective culture media.

system at systemic and mucosal levels (Ng et al., 2009).

bacteria and absence of translocation (Capriles et al., 2005).

assessments which will prove its probiotic efficiency (Figure 1).

**2. Effect of probiotics on human health** 

**2.1 Probiotic selection** 

Fig. 1. Probiotic selection chart.

Afterwards, a new culture is prepared only with the target colonies for *in vivo* assessment (pathogen inhibition, target species pathogenicity; resistance to host conditions; among others). If there are no restriction to the use of the target species, experiments with in vivo supplementation at big and small scale are carried out to check if there are real benefits to the host. Finally, the probiotic which presented significant satisfactory results can be commercially produced and used.

#### **2.2 Prevention or reduction of diarrhea symptoms**

One of the main applications of probiotic microorganisms is at preventing or in the treatment of gastrointestinal disturbances. In a clinical trial carried out with children hospitalized for acute rotavirus diarrhea, three treatments were assessed. The first group of children received oral rehydration therapy plus placebo; the second group was submitted to oral rehydration plus *Saccharomyces boulardii* treatment and the third group received oral rehydration and a compound containing *Lactobacillus acidophilus*, *Lactobacillus rhamnosus*, *Bifidobacterium longum* e *Saccharomyces boulardii*. Mean duration of diarrhea was shorter for the children who received the treatment with *Saccharomyces boulardii strain* (58 hours) and for the children who received the compound with for different microorganism strains (60 hours), when compared to the control group (84.5 hours) (Grandy et al., 2010). In Brazil, a double-blind, placebo controlled trial showed that protection against diarrhea (32.2% reduction in diarrhea during the first year of life) was obtained by oral inoculation with a single dose of plasmid-free human *Escherichia coli* EMO soon after birth (Figueiredo et al., 2001).

Treatment with antibiotics can cause an unbalance in the indigenous microbiota, increasing concentration of pathogenic microorganisms and toxin production, promoting diarrhea symptoms (Vasiljevic & Shah, 2008). A significant effect was observed in a study carried out with patients who presented diarrhea caused by antibiotics, in which intake of a probiotic drink containing *L. casei*, *L. bulgaricus* e *S. thermophilus* reduced the incidence of diarrhea (Hickson et al., 2007). In a double-blind, formula controlled trial performed in Brazil, a milk lyophilized formulation supplemented with *B. bifidum* and *S. thermophilus* was compared with another without supplementation for the prevention of antibiotic-associated diarrhea in children 6 to 36 months old. The authors observed a significant reduction of diarrhea frequency in children treated with the probiotic formula (16% of 80 patients) when compared to the control group (31% of 77 patients) (Corrêa et al., 2005). In another doubleblind, placebo controlled trial also performed in Brazil, the treatment with a lyophilized preparation of *S. boulardii* in children with acute diarrhea was evaluated and a reduction in duration of rotavirus diarrhea was observed in the group treated with the probiotic yeast (Corrêa et al., 2011). Other examples of clinical trials related to prevention or shortening of diarrhea symptoms by using probiotics are summarized in Table 1.

#### **2.3 Irritable bowel syndrome**

Irritable bowel syndrome is a diseased characterized by abdominal pain, diarrhea, constipation and mucus secretion along with feces (Vahedi et al., 2010). Although many physiopathology factors had been correlated to the cause of this disease, in the last years, researchers have considered feed intolerance and unbalance of intestinal microbiota as the main factors responsible for symptoms of the irritable bowel syndrome. Probiotics are a

The Benefits of Probiotics in Human and Animal Nutrition 81

A study conducted by Furrie et al. (2005) pointed the efficiency of *Bifidobacterium longum*  associated to inulin-oligofructose prebiotic in the treatment of ulcerative colitis. The treatment resulted in an improvement of the full clinical appearance in patients who

Saturated fat rich diets can increase serum cholesterol rates, which is one of the main risk factor for cardiovascular disease (Vasiljevic & Shah, 2008). Many studies have been carried out on the hypocholesterolemic activity of non-pathogenic bacteria through mechanism of hydrolysis of biliar salt (Pereira et al., 2003; Noriega et al., 2006; Parvez et al., 2006; Nguyen

Baroutkoub et al. (2010) observed that consumption of probiotic yogurt with *Lactobacillus acidophilus* and *Bifidobacteria* cepas by people with hypercholesterolemia resulted in the reduction of total cholesterol and LDL (Low Density Lipoproteins: it is believed they are the harmful class to human beings) and in the increase of good cholesterol, HDL (High Density Lipoproteins: it is believed that they are able to absorb cholesterol crystals which are deposited in arteries/veins wall, therefore delaying arteriosclerotic process) in the blood.

Despite the great number of studies, reduction of serum cholesterol effect by probiotics is not considered an established effect, yet. Thus, new clinical trials controlled by placebo

The fight against cancer is one of the biggest challenges faced by humanity. According to some authors, consumption of probiotic-supplemented products can prevent and even suppress tumor growth. According to Ma et al. (2010), *Bacillus polyfermenticus* was able to suppress in vitro and in vivo growth of cancer cells, suggesting that such microorganism can be used to prevent colon cancer development. Probiotic strains of *E. faecium* RM11 and *L. fermentum* RM28, isolated from fermented-milk were also shown to have antiproliferative properties against colon cancer cells, suggesting that such microorganisms can be used as an

It was observed in volunteer subjects who received *Lactobacillus rhamnosus* LC705 and *Propionibacterium freudenreichii* a reduction of intestinal absorption of aflatoxin B1, a toxin correlated to the high liver cancer index. Therefore, probiotic supplementation can be effective in preventing development of liver cancer and other types of cancer caused by

Probiotics are able to reduce *in vitro* various inflammatory cytokines and intestinal permeability, which are effects considered beneficial in allergic conditions. In addition, gut microbiota of atopic patients seems quite different, with an increase in clostridia and a decrease of bifidobacteria when compared to microbiota of non-atopic individuals. Studies have been performed to evaluate the effectiveness of probiotics in food allergy, atopic

should be carried out to prove the efficiency of those microorganisms.

alternative to colon cancer (Thirabunyanon et al., 2009).

environmental factors (El-Nezami et al., 2006).

eczema and rhinitis (Michail et al., 2006).

received this therapy.

et al., 2007).

**2.6 Cancer control** 

**2.7 Allergy** 

**2.5 Hypercholesterolemia** 


Table 1. Clinical trials on the use of probiotics in the treatment of diaheia

good alternative for the treatment of this syndrome inasmuch as the use of probiotic may lead to an unbalance of intestinal microbiota, making the carrier more susceptible to the disease (Rolfe, 2000).

Nagala & Routray (2010) studied the effect of a probiotic supplement containing *Lactobacillus acidophilus*, *Bifidobacterium bifidum*, *B. longum* and *B. lactis*, on patients with irritable bowel syndrome. It was observed a significant improvement after two months of the treatment, with 84% of the patients showing improvement in abdominal pain, 73.9% in bloating, 88% in flatulence, 90.9% in diarrhea and 86.9% in constipation.
