Functional Foods

Promising Health Benefits of Probiotics

Praneeta Singh, Sunil Kumar and K.P. Singh

THE beneficial effects of dahi, yoghurt, kefir, koumiss etc. on health are well known. These can be defined as live microbial food supplements, which beneficially influence the health of the host by improving its intestinal microbial balance. The historical association of probiotics with these fermented milk products stands true even today. Probiotic term is derived from a Greek word meaning ‘for life’. Probiotics are the live microorganisms which when ingested in sufficient quantity exert a positive effect on health in addition to traditional nutritional effects. The following microorganisms have been considered as human probiotics:

I.   Lactobacillus species: L. acidophilus, L. amylovorus, L. brevis, L. casei, L. casei subsp. rhamnosus (lactobacillus GG), L. caucasicus, L. crispatus, L. delbrueckii subsp. bulgaricus (L. bulgaricus), L. fermentum (L. fermenti), L .gasseri, L. helveticus, L. johnsonii, L. lactis, L. leichmannii, L. paracasei, L. plantarum, L. reuteri, L. rhamnosus.
II.  Bifidobacterim species: B. adolescentis, B. bifidum, B. breve, B. infantis, B. lactis (B. animalis), B. licheniformis, B. longum.
III. Other lactis acid bacteria: Enterococcus faecium, Lactococcus lactis, Leuconostoc mesenteroides, Pediococcus acidilactici, Streptococcus thermophilus.
IV. Non lactic acid bacteria: Bacillus subtilis, Escherichia coli strain nissle, Saccharomyces boulardii, S. cerevisiae.

An alternative approach for using the probiotics is the use of prebiotics. A prebiotics is a nondigestible food ingredient that beneficially affects the host by selectively stimulating the growth and/ or activity of one or a limited number of bacteria in the colon, that have potential to improve host health. The third approach is use of symbiotics, which have been defined as a mixture of probiotics, which beneficially affects the host by improving the survival and implantation of live microbial supplements in the gastrointestinal tract.

Due to indiscriminate use of antibiotics, a number of problems like antibiotic resistance, negative side effects and allergic reaction arise. This needs a suitable alternative to it; probiotics serve the purpose with ease and efficiency. All intestinal bacteria exist in dynamic balance with one another, but this balance may be disturbed in certain conditions like prolonged diseases, deprivation from food and water, travel by air, antibiotic and radiation therapy etc. This disturbance can be overcome by consuming fermented milk products containing probiotics. They affect the intestinal microflora in various ways. First, the constituents of products provide nutrients such as microsugars, breakdown product of K-casein etc., which support the growth of Bifidus type of intestinal microflora. Secondly some constituents like oxidation product of thiocyanate may also have antibacterial effect on some species of microflora. Thirdly many of the milk constituents promote the secretion of digestive enzymes and stimulate the peristaltic action of digestive tract, thereby affecting some specific bacteria. Finally, lactic acid bacteria (LAB) may become established within the digestive tract, thus affecting microbial balance of intestine (Sabiki and Mathur, 1997).

Most of the bacteria that are ingested die, when they reach the acid conditions of stomach. For a beneficial bacterium to be classified as a probiotic, it must be resistant to gastric, bile and pancreatic juices to reach the colon alive. The probiotics when attached to the wall of intestine increase the number of beneficial bacteria and fight against harmful bacteria thus maintaining a balance between the beneficial and harmful bacteria by following mechanisms:

  • Production of inhibitory substances.
  • Blocking of adhesion sites by competitive inhibition.
  • Competition for nutrients otherwise consumed by pathogenic microorganisms.
  • Stimulation of immunity.

Effect of probiotic bacteria on human health
Prevention of cardiovascular diseases:

Antihypertensive properties of fermented milks: Anti hypertensive activity has been shown by casein hydrolysate produced by an extracellular proteinase from L. helveticus (CP790) when tried in cases of rats. Recently two hypertensive peptides val-pro-pro and ile-pro-pro have been purified from sour milk formed by culture of L. helveticus and S. cerevisae. Inhibition of angiotensin converting enzyme occur by these peptides thus preventing the conversion of Angiotensin I to Angiotensin II that is a potent vasoconstrictor (Kansal, 2001).

Reduction of serum cholesterol: Mann (1977) found that large dietary intake of yoghurt lowered serum cholesterol. Since then many reports have appeared suggesting strain specific serum hypocholestrolemic effect of LAB, including Lactobacilli. Ingestion of fermented milks containing probiotic LAB might be a natural way to decrease serum cholesterol in human (Bazzare et al, 1983). Some of the organisms, which help to control serum cholesterol levels, are L. casei and Bifidobacterium sp (Gopal et al, 1996). Bifidobacterium longum also removes cholesterol from laboratory media much the same way as does L. acidophilus (Dambekodi and Gilliland, 1998). One important beneficial effect attributed to the L. acidophillus group is its ability to reduce serum cholesterol, possibly through binding of the dietary cholesterol with the cells (Gilliland et al, 1985) or deconjugation of bile salts in small intestine (Walker and Gilliland, 1993).

Probiotics in GIT problems:

GIT infections: Fermented milk products suppress the growth of pathogens, which are responsible for GIT infections. They help in treatment of the digestive tract infection by producing antibacterial substances such as lactic acid, peroxides and bacteriocins.

Infantile diarrhea: Rotavirus is one of the common causes of diarrhea in small children, though there are some other viral and bacterial pathogens also. If we supplement infant formulas with Bifidobacterium lactis and Streptococcus thermophillus, it is found to be effective against nosocomial diarrhea in infants. Paediatric beverage containing B. animalis, L. acidophilus and L. reuteri has been reported to be beneficial in prevention of rotavirus diarrhea. Systemic local immune response to rotavirus can be promoted by treatment with Lactobacillus GG (Kansal, 2001).

Antibiotic associated diarrhea: Most common cause of antibiotic associated diarrhea is C. difflcle. As antibiotic therapy is responsible for disrupting the intestinal microflora thereby enabling C. difficle to establish itself and produce toxins. Cultured milk used prophylactically may be helpful in preventing these side effects. B. longum, B. lactis, Lactobacillus GG, L. acidophilus La5 and Streptococcus faecium and yeast Saccharomyces boulardii are the probiotic microorganism which help in combating antibiotic associated diarrhea (Borgia et ah, 1982).

Traveller’s diarrhea: Though a large number of microorganisms are responsible for traveller's diarrhea but the most commonly found are enterotoxigenic E. coli. According to one report the incidence of diarrhea in Danish tourists to Egypt was reduced to 43 percent in treated group from 72 percent in control. The probiotics given were a mixture of live lyophilized L. acidophilus, B. lactis, L. bulgaricus and S. thermophilus (Black etal, 1989).
The underlying mechanisms for the resistance of enteric pathogens are:

  • Secretary immune effects
  • Colonization resistance
  • Alteration of intestinal conditions to be less favorable for pathogenecity (pH, short chain fatty acids, bacteriocins)
  • Alteration in toxin binding sites
  • Influence on gut flora population
  • Adherence to intestinal mucosa, interfering with pathogen adherence
  • Upregulation of intestinal mucin production, interfering with pathogen attachment to intestinal epithelial cells (Sanders, 1999).

Constipation: Several reports support of effect of fermented milks on the bowel to prevent constipation. Reported benefits include alleviation of constipation using L. acidophilus NCDO 1748, L. casei, and Lactobacillus GG (Benno et ah, 1984).

Lactose intolerance: A large number of people are unable to consume milk and milk products due to congenital deficiency of enzyme ?-galactosidase resulting in the inability to digest lactose. On reaching the large bowel lactose, which remains indigested, is acted upon by bacterial enzymes, causing osmotic flatulence leading to abdominal pain after consumption of milk. There are several incidences that lactose intolerant people suffer fewer symptoms when fed with fermented milk products in place of milk. As the bacteria present in these products hydrolyze lactose and lower its concentration.

Cancer prevention

Calcium, milk proteins and fat components of fermented milk products such as butyric acid, isopalmitic acid and sphingomyelin, together with lactic acid bacteria act as protective substances against cancer. In in vitro studies L. acidophilus and Bifidobacterium have shown significant inhibitory effect on the growth of human breast cancer cell line MCF7 (Biffi et ah, 1997). In two studies carried out in Japan it has been shown that oral intake of L. casei preparation had a positive effect on the prevention of recurrence of superficial bladder cancer (Aso et ah, 1995). The mechanisms behind this are in several forms:
i.   These probiotic bacteria may bind mutagens,
ii.  They may cause carcinogen deactivation,
iii. Lactic acid bacteria also lower the carcinogenicity indirectly by decreasing intestinal carcinogen activating bacterial enzymes and
iv.  Immune responses and influence on secondary bile concentration are also responsible for cancer prevention.

Immune responses

The probiotics in fermented milk products help in immune stimulation. They increase the concentration of interferons and immunoglobulins like immunogenic substances. The probiotics also have adjuvant like effect in antigen specific immune responses. Along with this they strengthen the non-specific defense against infection and tumours (Sanders, 1999).

Urogenital infections

Probiotics bacteria decrease the level of uraemic toxins like phenol, p-cresol and indican and inhibit the production of H2O2 or biosurfactant, thereby preventing the urogenital infection. Effective colonization resistance and adhesion to urinary and genital tract cells have also been shown to be responsible for it.

Hepatic encephalopathy:
Bacterial urease present in the intestine is responsible for the production of ammonia, which can be toxified in liver. In case of patients suffering with liver failure, detoxification is impaired, thereby causing a neurological disorder called hepatic encephalopathy. Probiotics bacteria may be helpful in this case by binding with urease producing gut flora (Sanders, 1999).


A breakdown of intestine's mucosal barrier function allowing extensive antigen challenge may be a factor in some allergic reactions. The probiotic bacteria improve the mucosal barrier function thereby moderating the allergic responses. All together the mechanism behind the prophylaxis of allergies is the prevention of antigen translocation into the blood stream, thereby preventing the allergic reactions (Sanders, 1999).
Fermented milk products appear to be perfect medium for ingestion of probiotics. Consumption of these products should be promoted, as there is no health risk associated with probiotics. Rather many benefits are possible. Thus, we can say that, the probiotics have potential to be an ingredient of food with healthy image and they can be potent replacer for antibiotics.





  1. Aso, Y., Akazan, H., Kotake, T., Tsukamoto, T., Imai, K. and Natia, S. (1995). Preventive effect of a Lactobacillus casei preparation on reccurence of superficial bladder cancer in a double blind trial. Eur. Vrol. 27: 104-109.
  2. Bazzare, T.L., Liuwu, S. and Yuhas, J.M. (1983). Total and HDL cholesterol concentration following yoghurt and calcium supplementation. Nutr. Rep. Int. 28: 1225-1232.
  3. Benno, Y., Sawada, K. and Mitsuoka, T. (1984). The intestinal microflora of infants: composition of faecal flora in breast fed and bottle fed infants. Microbiol. Immunol. 28: 975-986.
  4. Biffi, A., Coradini, D., Larsen, R., Riva, L. and Di Fronjo, G. (1997). Antiproliferative effect of fermented milk on the growth of a human breast cancer cell line. Nutrition and Cancer, 28: 93-99.
  5. Black, F.T., Anderson, P.L., Yrskov, F., Gaarselev, K. and Laulund, S. (1989). Prophylactic efficacy of Lactobacilli on traveller's diarrhea. Travel Med, 8: 333-335.
  6. Borgia, M., Sepe, N., Brancato, V. and Borgia, R.A. (1982). A controlled clinical study on Streptococcus faecium preparation for the prevention of side reactions during long term antibiotic therapy. Curr. Ther. 31: 265-271.
  7. Dambekodi, P.C. and Gilliland, S.E. (1998). Incorporation of cholesterol into the cellular membrane of Bifidobacterium longum. J. Dairy Sci. 81: 1818-1822.
  8. Gilliland, S.E., Nelson, C.R. and Maxwell, C.V. (1985). Assimilation of cholesterol by Lactobacillus acidophilus. Appl. Environ. Microbiol. 49: 377-381.
  9. Gopal, A., Shah, N.P. and Roginski, H. (1996). Bile tolerance, taurocholate deconjugation and cholesterol removal by Lactobacillus acidophilus and Bifidobacterium spp. Initechnissensehaft 51:619-623.
  10. Kansal, V.K. (2001). Probiotics application of culture and culture containing milk products. Indian Dairyman 53(8): 49-54.
  11. Mann, G.V. (1977). A factor in yoghurt which lowers cholesterolemia in man. Atherosclerosis 26: 335-340.
  12. Sabiki, L. and Mathur, B.N. (1997). Probiotics cheese: Some novel challenges for contem   porary research. Indian Dairyman 49(12): 5-9.
  13. Sanders, M.E. (1999). Probiotics. Food Tech. 53(11): 67-76.
  14. Walker and Gilliland, S.E. (1993). Relationship among bile tolerance, bile salt deconjugation and assimilation of cholesterol by Lactobacillus acidophilus. J. Dairy Sci. (76): 956-961.

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