Probiotics: disease preventing bacteria!!

Probiotic Effects on Cold and Influenza-Like Symptom Incidence and Duration in Children
Gregory J. Leyer, Shuguang Li, Mohamed E. Mubasher, Cheryl Reifer, and Arthur C. Ouwehand
Pediatrics 2009; 124: e172-e179.

http://pediatrics.aappublications.org/cgi/content/abstract/124/2/e172

In a double-blind, placebo controlled study done on 326 Chinese children aged 3 to 5 years, researches have found that twice daily administration of probiotics resulted in a marked reduction in incidence of cold and influenza-like symptoms.

The children who participated in this study were divided into three groups. One group received milk that contained Lactobacillus acidophilus (Lactobacillus group), the other received milk containing a combination of Lactobacillus acidophilus and Bifidobacterium animalis (Lactobacillus/Bifidobacterium group) and a third group received plain milk (placebo group). Each group had approximately 100 children. Milk was administered twice daily by school authorities during weekdays and at home during weekends for a period of 6 months. The children were closely monitored during this period and some of the important observations were as follows:

1. Compared to the placebo group, the Lactobacillus group had 53 percent fewer episodes of fevers, 41 percent fewer episodes of cough, and 28 percent fewer episodes of rhinorrhoea (runny nose).

2. The Lactobacillus/Bifidobacterium group had even larger reductions in symptom rates: 72 percent fewer fevers, 62 percent fewer coughs, and 59 percent fewer runny noses.

3. Duration of illnesses when they did occur in children receiving probiotics was significantly lower than the control group. Compared to placebo, the length of illness was decreased by 32 percent with Lactobacillus and by 48 percent with Lactobacillus/Bifidobacterium.

4. Antibiotic use was 68 percent lower in the Lactobacillus group and 84 percent lower in the Lactobacillus/Bifidobacterium group, compared to the placebo group.

5. Children who received the probiotics were absent from day care 28 to 32 percent less often than children in the placebo group.

Earlier studies had shown that probiotics were able to boost the immune response to certain types of bacterial and viral illnesses. However, this is the first time that probiotic use has been convincingly shown to prevent illnesses.

Probiotics are defined as live microorganisms which when administered in adequate amounts confer a health benefit on the host. They are usually given as dietary supplements. Lactobacillus and Bifidobacterium are the most commonly used probiotics.

A large amount of research is being done to explore the potential of probiotics in the prevention and treatment of a wide variety of clinical conditions. Some indications for probiotics have sound scientific basis, while others are still in the realms of speculation. Some of the approved indications for probiotics are:

1. Managing lactose intolerance

2. Prevention of colon cancer

3. Lowering cholesterol

4. Lowering blood pressure

5. Improving immune function and preventing infections

6. Helicobacter pylori induced peptic ulcers

7. Antibiotic-associated diarrhea

8. Reducing inflammation

9. Improving mineral absorption

10. Prevents harmful bacterial growth under stress

11. Irritable bowel syndrome and colitis

It was the Russian scientist Eli Metchnikoff who initially introduced the idea of supplementing the diet with friendly bacteria. Metchnikoff, while working at the Pasteur Institute in Paris, noticed that rural people in Bulgaria and other places in Europe, whose diet was rich in “milk fermented with lactic acid bacillus” were exceptionally long lived. He proposed that the lactic acid bacteria replaced harmful proteolytic bacteria (like Clostredia) in the gut. The proteolyic bacteria could produce toxic substances by digesting protein and these toxic substances eventually lead to age related changes and senility. This theory was called the “auto intoxication” theory of Metchnikoff. Metchnikoff himself started supplementing his diet with lactic acid bacilli called the “Bulgerian bacillus” and his health apparently improved. The practice soon caught on and patients were routinely put on a sour milk diet by physicians in Paris.

Five years after Metchnikoff death in 1915, it was demonstrated by Rettger that Metchnikoff’s “Bulgarian bacillus” was not capable of colonizing the human gut. After this discovery, Metchnikoff theory of longevity through consumption of lactic acid bacteria was questioned and soon became unpopular. However, other bacteria with health benefits were being discovered in the meantime. Henry Tissier (also of the Pasteur Institute) discovered the Bifidobacterium and advocated the use of this bacterium in the treatment of childhood diarrhea. A German doctor, Alfred Nissle isolated strains of E. coli that were able to prevent salmonellosis and shigellosis.

Since these discoveries, many more bacteria have been added to the probiotic list. Each bacterium has its own unique mechanisms of producing beneficial effects and mechanisms elucidated in one strain cannot be extrapolated to other probiotics even if they are closely related bacteria.

Recently there have been certain controversies regarding the use of probiotics. In a clinical trial conducted at the University of Western Australia aimed at showing the effectiveness of probiotics in reducing childhood allergies, 178 children were given either a probiotic or a placebo for the first six months of their life. Those given the good bacteria were more, not less, likely to develop a sensitivity to allergens.

In another instance, a double-blind, placebo-controlled therapeutic study on the effects of a probiotic cocktail on pancreatitis at University Medical Center Utrecht (UMC) showed that 24 out of 296 patients died between 2004 and 2007, with more deaths among those receiving the probiotic cocktail.

However, there have also been well designed studies that have shown beneficial effects of probiotics. The study that is described in this post is one such example. Clearly this is not the last we will hear of probiotics and their therapeutic benefits.

Acknowledgements:
Wikipedia article on Probiotics.