February 2001

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The colon of the human gastrointestinal tract contains a large population of resident bacteria. In fact, approximately 55% of the solids in faeces is microbial biomass. In adults, these bacteria are balanced in a complex ecosystem consisting of more than 40 major species and more than 400 species in total (1).

In a healthy individual, most of these species are advantageous or benign to the host, but some are potentially pathogenic if their numbers are allowed to increase to high levels. Disturbances to the ecological balance in the intestinal microflora caused by, for example, changes in diet, stress or antibiotic treatment can lead to the overgrowth of deleterious bacteria, and subsequently to gastrointestinal disorders (2). These disorders may be as minor as intestinal discomfort or increased flatulence, or relative serious health problems such as severe diarrhoea, irritable bowel syndrome and colitis. Undesirable bacteria in the colon have even been implicated in the development of colon cancer (3).

Oligofructose is derived from a plant source (usually chicory or sucrose) and consists of fructose chains of up to several units. It is a resistant starch, or soluble dietary fibre, that is not absorbed in the small intestine and passes into the large intestine where it is partly fermented, producing an energy value of 6 - 8 kilojoules/gm.

Carbohydrates are normally absorbed in the small intestine and directly metabolised in the liver, generating 17 kilojoules/gm. Complex fibres produce little or no energy and are broken down by bacteria to some degree in the large intestine.

Resistant starches are neither fibres or complex carbohydrates, and were for many years a dilemma for the Food Authorities. They are now recognised under the carbohydrate banner and are listed on nutritional panels as soluble dietary fibre.

Oligofructose is a tremendous substrate for bifidus bacteria, stimulating its activity by several hundred percent. This is called prebiotic activity, referring to stimulation of health promoting bacteria in the intestinal tract. Short chain fatty acids are produced, lowering pH levels and providing an energy source for the growth and maintenance of large intestine cells. This process leads to differentiation of cancer cells, a vital step that is required before cancer cells can be killed.

The ideal environment for healthy bacteria is quite different to the environment preferred by pathogens and gram negative putrefactive bacteria. Consequently the undesirable bacteria diminish in number as the healthy bacteria proliferate in the presence of oligofructose.

One type of undesirable bacteria are faecal bacteria that thrive in the presence of unabsorbed iron. This leads to the production of oxygen radicals that are known to damage protein, lipids and DNA. This damage has been implicated in the induction of somatic cell mutations that may favour the development of several forms of cancer (4).

There is some limited evidence that habitual intake of dietary fibre may suppress the production of reactive oxygen species (5).

A colon high in faecal iron levels would benefit substantially from oligofructose consumption, creating an environment unfavourable for the growth of iron loving bacteria. The microflora balance would gradually shift from the putrefactive to the healthy, increasing the growth of probiotic bacteria such as lactobacillus, bifidus, acidophilus and enterococcus. Moreover, probiotics might prevent infection because they compete with pathogenic viruses or bacteria for binding sites on epithelial cells (6). Diarrhea due to the growth of pathogenic bacteria is the most common side effect of antibiotic use. Probiotics might inhibit this growth by releasing inhibitory substances, as indeed has been shown in vitro by some strains (7).

Desirable bacterial numbers can also be increased by consuming cultured products such as yoghurt but in many cases they are not very effective because many bacteria are destroyed in the stomach and small intestine. Upon reaching the colon or large intestine the surviving bacteria are often present is such low numbers that any likely benefit is doubtful. This especially happens with commercial yoghurt that has a shelf life of several weeks, with bacterial numbers possibly already low before consumption. Yoghurt manufacturers have addressed the problem by including oligofructose in the yoghurt so that surviving bacteria are rejuvenated once they reach the colon.

The enclosed citrus flavoured fruit drink offers the opportunity to improve intestinal health and add valuable calcium to the diet. Each 200 ml serve contains 1.5 gms of oligofructose and 400mgs of calcium in a non-dairy product. It has a very strong message, especially now that oligofructose is recognised as a soluble dietary fibre by ANZFA. The two ingredients are very complimentary, with oligofructose increasing calcium absorption to produce a product containing high levels of good quality calcium in a pleasant drink with a range of intestinal benefits.

BIBLIOGRAPHY

1. Tannock,G.W.1995
2. Marteau, P. and Rambaud,J.C.(1993) FEMS Microbial.Rev.12,207-220.
3. Tomomatsu,H(1994)Food Technol.48,61-65.
4. Lund et al, Am J Clin Nutr 1999;69:250-5
5. Lund et al, Am J Clin Nutr 1999;69:250-5
6. Perdigon et al, J Dairy Sci 1995;78:1597-606)
7. Bhatia et al, J Clin Microbiol 1989;27:2328-30