The invention relates to the prebiotic effect of oligosaccharides on the intestinal flora of mammals.

A prebiotic is a non-digestible food compound that can be broken down by the microorganisms of the intestinal flora. This breakdown gives rise to an effect on the intestinal flora of the mammal, beneficial to the health thereof since it leads to development of certain bacteria of the flora. Among these, bifidobacteria are known for having an important role, for example in the immune system of the hosts. Their selective development by virtue of prebiotic compounds

(bifidogenic prebiotic effect) is therefore beneficial to the well-being of the host mammal. Therefore, the prebiotic effect of a non-living compound refers to the change, both in composition and in activity, of the intestinal flora of the host due to the ingestion of this compound, when this change has a beneficial effect on the well-being and/or the health of the host (see: Gibson and Roberfroid, J. Nutr, 125, 1401, 1995).

It should be noted that probiotic refers, on the other hand, to a food supplement comprising living microorganisms, when these microorganisms have a beneficial effect on the host by improving the balance of its intestinal flora (see: Fuller, J. of Applied Bacteriology, 66 (5), 365-378, 1989).

The prebiotic effect of certains oligosaccharides is known. Described in FR2844453 is the prebiotic effect of non-digestible oligosaccharides comprising chain formations of identical or different monosaccharides, the degree of polymerization of which varies between 2 and 10. These oligosaccharides, via their prebiotic effect, may contribute to the prevention of type II diabetes.

However, the prebiotic use of oligosaccharides in FR2844453 is intended for patients predisposed to type II diabetes. Taking oligosaccharides is similar to taking medication.

The invention aims to improve the well-being of healthy mammals, via acting on their intestinal flora.

Consequently, the invention relates to galactofructose for its prebiotic effect on the intestinal flora of mammals, when it is incorporated into a food composition and when this is absorbed by the mammal in an amount corresponding to daily doses of galactofructose, averaged over 30 days, of between 0.05 and 0.5 g.

Galactofructose, also called lactulose, is a disaccharide formed from the combination of two monosaccharide molecules, fructose and galactose. Its chemical formula is (4-0-p-D-Galactopyranosyl-P-D-fructofuranose). It is an isomerization product of lactose, which both have the same empirical formula

(Ci ₂ H ₂₂ 0) i) and molecular weight (342.3).

It has been observed that galactofructose, when it is absorbed in small amounts according to the invention in food compositions, improves the well- being of mammals. The invention also has the advantage of not interfering with the taste and the appearance (for example colour) of the food compositions.

The galactofructose according to the invention is incorporated into a food composition. The expression "food composition" is understood to mean a composition intended for feeding mammals. The mammals are preferably human beings, although the invention can also be used for improving the well-being of various mammalian animals, such as domestic animals. The food composition is advantageously a composition absorbed regularly, preferably at least once a week, more preferably several times a week, and particularly preferably daily.

Food compositions for human beings comprising at least one foodstuff such as bread, butter, milk, fermented dairy products, cereals, biscuits, beverages and fruit juices are advantageous.

In one particularly preferred embodiment of the invention, the food compositions are intended for feeding children. A food composition comprising powdered milk intended for infant feed is one example of a food composition for which the invention is particularly suitable.

According to the invention, the galactofructose is absorbed in daily amounts, averaged over 30 days, of between 0.05 and 0.5 gram. This means that the daily doses may vary but that the total dose absorbed over one month divided by 30 is between 0.05 and 0.5 g.

In a first advantageous embodiment, the amounts are averaged over 7 days, which means that the total dose absorbed over seven days divided by 7 is between 0.05 and 0.5 g.

In another advantageous embodiment of the invention, the daily doses of galactofructose, averaged over 30 days, are between 0.1 and 0.5 g, more advantageously between 0.2 and 0.5 and more advantageously still between 0.2 and 0.4 g. It is recommended that the daily dose absorbed, not averaged, does not exceed 5 g, preferably does not exceed 2.5 g, more preferably does not exceed

In one preferred variant, the daily doses of galactofructose are between 0.1 and 0.5 g, over at least 7 days, preferably at least 14 days, more preferably at least 30 days. In this variant, galactofructose is absorbed regularly every day and the doses are no longer averages, but daily estimated values.

The prebiotic effect according to the invention is demonstrated in concrete terms by an increase in the population of bifidobacteria in the intestinal flora of the host mammal. This increase is at least 10%, generally at least 25%, often at least 50%. Preferably, the population is at least doubled. Particularly preferably, the population of Bifidobacterium spp bifidobacteria, expressed in log 10, is increased by 0.5 at least, which corresponds to a multiplication of the population by a factor of around 3 at least. Bifidobacterium spp bifidobacteria protect the gut against colonization by pathogenic bacteria. This protection results, on the one hand, from the competition at the surface of the cells, from the competition for essential nutrients, from the production of antimicrobial agents and from the production of compounds comprising short-chain fatty acids, which decrease the pH of the faeces and inhibit the development of pathogenic bacteria.

Bifidobacterium spp bifidobacteria are also associated with a strengthening of the immune system, especially in children, and with a preventive action against cancer, via a reduction in the activity of enzymes that convert procarcinogenic substances into carcinogenic substances (see von Wright et al., Eur J.

Gastroenterol. Hepatol. November 1999, 11(11), pp. 1195-1198).

Owing to the invention, the increase in the population of bifidobacteria does not require any probiotic in the food composition. It is even recommended that the composition be substantially free thereof. The expression "substantially free of probiotics", is understood to mean that the food composition alone, in the absence of galactofructose, gives rise to an increase in the population of

Bifidobacterium spp of less than 10%, generally of less than 5%.

The invention is preferably aimed at mammals in good health, exhibiting no signs of disease. It makes it possible to improve their well-being. Under certain circumstances, it also makes it possible to protect their good health, in a preventative manner.

The invention also relates to a food composition as is, comprising galactofructose for its prebiotic effect on the intestinal flora of mammals, when the food composition is absorbed in an amount corresponding to daily doses of galactofructose, averaged over 30 days, of between 0.05 and 0.5 g.

In the same way as for the galactofructose according to the invention, the food composition according to the invention is advantageously a regularly absorbed composition, and preferably contains a foodstuff intended for children, such as powdered milk for infant feed.

In one preferred embodiment variant of the food composition according to the invention, this is also substantially free of probiotics.

The invention also relates to a prepackaged dose of the composition as herein described, comprising from 0.1 to 0.5 gram of galactofructose. It is recommended to absorb such a dose daily.

The invention finally relates to a process for manufacturing a composition according to the invention, according to which a galactofructose powder, having a water content of less than 5% by weight and an average particle size D50 of less than 500 μπι, is mixed with a foodstuff. The powder may be manufactured according to the process described in FR2898516.

The process according to the invention is particularly advantageous when the foodstuff is itself in powder form, as is the case of milk powders for feeding children, for example.

The following example serves to illustrate the invention.

Example

20 human volunteers, aged from 18 to 50 years old, having a body mass index of between 20 and 30 were randomly split into two groups of 10, one group absorbing, every day, for 30 days, a 20 cl glass of milk produced from powdered milk to which 0.5 g of Solactis ^® powder are added, corresponding to 0.3 g of galactofructose, and the other group absorbing a placebo. The volunteers did not display any sign of disease, in particular of intestinal disease. They had never participated in a test relating to prebiotics or probiotics. During the test they did not absorb any probiotic. Yoghurts were avoided. The bifidobacterium spp population of the faeces before the test, measured by the FISH (Fluorescence In Situ Hybridization) technique was around 8.5 logl O cells/g faeces on average. At the end of the test (30 days), this population increased to around 9 log 10 in the group absorbing galactofructose according to the invention. No significant variation (taking into account natural variations in measurement) was observed in the placebo group. 30 days after the end of the ingestion, the bifidobacterium population of the galactofructose group returned to a value close to 8.75 on average. Furthermore, it was verified that the total population of anaerobic bacteria varied little during and after the test, both in the galactofructose group and in the placebo group.