Winter 2000 Issue — Probiotic Lactic Acid
Bacteria in Functional Foods

Maija Saxelin PhD

Valio Ltd.

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The use of probiotic (beneficial) bacteria has a long tradition. However, acceptance of the idea has only come with increased awareness on the importance of sound scientific documentation on the effects of these bacteria. Because of differences in characteristics and effects of different bacterial species or even different strains within the same species, both strain identification and the quantity of bacteria in a product have become increasingly important. It is no longer acceptable to extrapolate from results of studies carried out on a strain other than the one in your product.

Lactobacillus GG (LGG®)

Lactobacillus GG (L. rhamnosus strain GG, ATCC 53 103) was one of the first specified strains with an identity and good clinical documentation. It was isolated in the early 80s from the normal flora of a healthy adult. Since then, more than 100 scientific articles have been published, describing the characteristics of the strain, at least 50% describing clinical or human intervention studies. The most important health benefits documented on Lactobacillus GG are:

• Survival in the intestine and temporary colonisation of the intestinal tract
• Beneficial modulation of the intestinal microecology
• Prevention and treatment of acute diarrhoea
• Enhancement of natural intestinal resistance
• Restoration of a disturbed mucosal barrier
• Alleviation of food allergy during antigen elimination

Colonises the human digestive tract and balances the intestinal microecology

Lactobacillus GG tolerates acidic conditions in the stomach and the bile acids in the small intestine. It is therefore able to survive the passage through the gastronintestinal tract and can be recovered viable in stool samples. Lactobacillus GG adheres to both intestinal mucus and epithelial cells. The strain can be recovered in biopsy samples of the colon during its oral consumption, but it is eliminated from the mucosa within a week of cessation of consumption. The modulation of the colon milieu can be shown in the composition of faecal microflora and in the level of certain faecal enzymes. In healthy persons a consumption of a milk product fermented with Lactobacillus GG has been shown to increase beneficial bacterial flora (lactobacilli and bifidobacreria) and to reduce certain groups C: ::oren7:allv harmful ci ~:ri~ i __ Changes in enzyme acin-iries in ~n:es::nal content ~ndica:e chanaes in :he ra:~c bacterial quantities andyor in their activities. Certain hydrolytic enzymes in the colon, which are of microbial origin, are supposed to increase the risk of tumour formation. During human dietary consumption of products with Lactobacillus GG, the activity of such enzymes (13-glucosidase, nitroreductase, glycocholic acid hydrolase) was decreased significantly. In an animal study rats fed on a high-corn oil diet and injected weekly with a carcinogenic chemical, produced less tumours when their diet contained Lactobacillus GG, compared to a placebo. Lactobacillus GG also binds mycotoxins and other microbial toxins, improving intestinal health.

Prevents diarrhoea

Lactobacilli are popular in the prevention of traveller's diarrhoea, although their effect is not very well documented. In an American study with several destinations in developing countries the risk of having diarrhoea was significantly reduced with Lactobacillus GG capsules, compared to the placebo group. Volunteers in the active group suffered from diarrhoea only about half as often as in the placebo's. In another study with Finnish tourists in Turkey, the incidence of intestinal problems was significantly reduced in one destination, but the protection was less clear in another destination, indicating possible differences in infectious factors. Antibiotic treatment may disturb the intestinal microflora and intestinal symptoms are quite common. Lactobacillus GG capsules were shown to restore bacterial balance in the intestine during a antibiotic treatment of shigellosis. It reduced intestinal discomfort, diarrhoea and stomach pain to less than half when given with common antibiotics to children suffering from respiratory, urinary, skin or soft tissue infections. A similar protective effect by Lactobacillus GG­fermented yoghurt was seen during an erythromycin treatment of adult volunteers. Intestinal disorders caused by antibiotics are not just temporary inconvenience, but can lead to chronic infection caused by the opportunistic pathogen Clostridium difficile. Recurrent episodes of abdominal discomfort and diarrhoea are common and can lead to pseudomembraneous colitis. The treatment of C. difficile infection with Lactobacillus GG is promising. ABout 94 per cent of the 40 patients treated recovered, and a placebo-controlled study is still going on. An authentic community study in Peru showed that Lactobacillus GG capsules even prevented the incidence of diarrhoea among undernourished children. In particular non-breast-fed children received protection with the probiotic, when compared to the placebo, but still, clearly, the first essential is to improve the low standards of hygiene in households and the environment.

Speeds recovery in diarrhoea

Rotavirus is the most common infecting agent in acute gastro-enteritis in infants and young children in western countries. The probiotic treatment of rotavirus infections with Lactobacillus GG (after or during oral re-hydration) has been investigated in several placebo-controlled double-blind studies in Finland, Italy, Russia and in a multicentre study conducted by the European Paediatric Society. In all these studies the duration of diarrhoea in hospital was shortened by one to three days. Lactobacillus GG was as effective in a fermented milk product as in freeze-dried powder form, but the shortening effect is greatest when taken as early as possible. In comparison to another Lactobacillus rhamnous strain and to yoghurt starter strains Lactobacillus GG was the only one to shorten the duration of the diarrhoea, showing the difference in the efficacy of the strains. In an ambulatory study, Lactobacillus GG shortened the duration of acute diarrhoea to half compared to the placebo. In addition to the results with well-nourished children, a significantly speeded-up recovery from diarrhoea was recorded in studies with hospitalised children in Thailand and Pakistan. In these studies Lactobacillus GG was shown to be effective in the treatment of water diarrhoea but not in cases with bloody diarrhoea.

Enhances natural intestinal resistance

Lactobacilli enhance the colonisation resistance of the intestine against infection by balancing the microbial flora. Another important factor is the immune response evoked by bacteria in the gut-associated lymphoid tissue. The production of immunoglobulins is increased in intestinal infections such as rotavirus diarrhoea. Lactobacillus GG has been shown to enhan:­the formation of both specific and non­specific antibodies against rotavirus. It has also boosted antibody formation during ora vaccination.

The permeability of the gut mucosa is increased during intestinal disorders such as acute diarrhoea or food allergy, leading to a aberrant transport of macromolecules. In experimental studies with rat pups, the abnormal transport was cured by supplementation with Lactobacillus GG. It also normalised local antibody formation and the integrity of the mucosa, diminishing the transport of intact molecules through the jejunal mucosa. There is also evidence that Lactobacillus GG has a positive influence on intestinal mucosal permeability during chronic inflammation. Such studies have been conducted on patients with Crohn's disease and juvenile chronic arthritis, resulting in an enhanced intestinal defence mechanism and decreased inflammation.

Speeds recovery in food allergy

An adverse immune reaction to dietary antigens leads to food allergy giving symptoms of intestinal inflammation, atopic dermatitis and respiratory wheezing. Mucosal permeability is interrupted and aberrant antigen transport enhances the disturbed immune response. The condition can be corrected by elimination of the antigen from the intestine and by restoring the mucosal barrier with selected probiotic bacteria. Lactobacillus GG was shown to guide the immune response from a hyper­sensitised route to a healthy response. In clinical studies with milk-allergic children, Lactobacillus GG significantly speeded the recovery of atopic dermatitis and intestinal inflammation when it was administered during a milk elimination diet.

Consumer products with Lactobacillus GG

Lactobacillus GG can be used in various types of products. In fermented products it combines perfectly with other starter bacteria and the shelf life of the strain is excellent. In addition to the most common carbohydrates (other than lactose) it can ferment such compounds as 3-gluco-oligosaccharides from oat bran, allowing the possibility of creating new and healthy product.

Dairy-based applications:

• yoghurts
• drinking yoghurts
• fermented milks
• fermented whey-drinks
• dairy drinks (e.g. milk-juice mixes)
• sweet milk
• hard cheeses
• cottage cheeses
• fresh cheeses
• ice creams
• infant formulae
• etc.

Non-dairy food applications:

• juices
• various dietary foods
• etc.

Non-food applications:

• capsules, tablets and sachets
• products for oral re-hydration
• etc.

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