Prebiotics: chicory inulin and oligofructose ready to boom

The prebiotic market has to be seen in its broad context, the area of digestive health. However, some insoluble fibres have significant effects on the intestinal transit, and thereby indirectly improving our intestinal system, they are not considered as health improving fibres, as their effect is purely physical.

Healthy (prebiotic) fibres need to stimulate particular beneficial species in order to improve the health and wellbeing of its host.

The market of gut health is dominated by two substances: probiotics and prebiotics. This market has been growing gradually between 2001 and 2004, but has seen an explosive growth between 2005 and today. Gut health promoting substances are now found in dairy, beverages, baked goods, cereals, ice cream, snacks and savoury products.

With a number one position among the top five health claims in most regions, it is the biggest growth area within the healthy food sector (Fig.1). The top five health claims in the food market include digestive health, cardiovascular health, bone health, immune system and brain and nervous system.

The concept of prebiotic has been defined for the first time in 1995 as: "Non-digestible food ingredients that beneficially affect the host by selectively stimulating the growth and/or activity of one or a limited number of bacterial species already resident in the colon, and thus attempt to improve host health" (Gibson & Roberfroid, 1995).

Many non-digestible substances that are susceptible to be fermented in the large intestine claim that they are prebiotic.

However, to date, only few of them have demonstrated that they are selectively fermented by the resident beneficial microflora with the associated health benefits.

According to a review from Gibson, only few ingredients are able to fulfill the conditions to be considered as true prebiotics:

- The substance must be neither hydrolysed, nor absorbed in the upper part of the gastrointestinal tract.

- It must be selectively fermented by one or a limited number of potentially beneficial bacteria in the colon.

- It must preferably induce effects that are beneficial to the host health by modification of the composition of the colonic microbiota.

Chicory fructans (inulin, oligofructose) are one of the true prebiotic substances (namely, FOS and inulin, GOS and lactulose): "Together, the evidence available today both from in vitro and in vivo experiments supports the classification of inulin and oligofructose as prebiotic, since they fulfil all three criteria" (Gibson et al, 2004).

A similar conclusion can be found in other sources such as a scientific report of the French Food Safety Agency on prebiotics where only inulin and FOS are recognised as true prebiotics whereas several other substances, such as resistant dextrins are presented as candidates only (AFSSA, 2005).

The prebiotic effect of chicory inulin is well-documented through more than 50 clinical studies published in well-know and peer-reviewed journals. Moreover this effect has been demonstrated in various populations: from infants to elderly and with European, Asian and American volunteers.

The scientific data support a daily dose of 5g for a significant prebiotic effect of chicory inulin oligofructose (Rao, 2001; Bouhnik et al, 2007; Kolida et al, 2007). This dose has been validated by official statements in several countries such as France, the Netherlands, Germany, Malaysia, Brazil, etc.

The key mechanism in the prebiotic effect of chicory ingredients is their complete fermentation in the large intestine.

Several non-starch polysaccharides are able to stimulate overall colonic growth by being used as substrate by many micro-organisms in the colon. However, to date, few of them have been able to demonstrate the specificity of this stimulation. Chicory fructans are amongst the few.

Do you know that inulin is a molecule naturally present in many fruits and vegetables consumed in the traditional human diet for centuries? For example, it is possible to find inulin in onion, leek, garlic and even banana.

However, one of the highest concentration of inulin can be found in chicory. Chicory is a local agricultural ressource grown in Belgium, the north part of France and the Netherlands. Cosucra Groupe Warcoing is strongly involved in the seeding and growing of chicory roots through a strong partnership with its planters and with a dominant position in the seeds selection and production.

Chicory inulin is extracted from the chicory root by a gentle process based on simple hot water extraction. Cosucra Groupe Warcoing is following an environmental policy for waste selection and its valorisation, and energy control.

A significant part (70 per cent) of the electricity is produced on-site by a cogeneration power plant. This green electricity is obtained by firing natural gas and biogas coming from the waste treatment plant.

Many other non-digestible substances are obtained through enzymatic or chemical synthesis or polymerisation and are not from natural origin. In most cases they have a food aditive number in the EU, which cause some concerns to food manufacturers, food distributers and consumer groups.

According to the most well-know definitions of dietary fibre, chicory inulin and oligofructose are dietary fibres.

Moreover, chicory inulin and oligofructose are recognized and labelled as dietary fibre in several European Member States (France, UK, Belgium, Netherlands, etc) and in most of the countries of the world since the end of the 1990s.

For many non-digestible substances, advisory statements are required on the labelling of foodstuffs containing them. This is not the case for chicory inulin for which no ADI (Acceptable Daily Intake) have never been set by national authorities.

The caloric value of Cosucra's Fibruline/Fibrulose range is ranging from 0.97 to 1.2kcal/g, making it one of the lowest caloric fibres available today.

The complete fermentation of chicory inulin in the large intestine which is associated with its benefits on the intestinal microflora, may sometimes lead to some unwanted side-effects such as flatulence. However this complete fermentation is also the reason why chicory inulin is so efficient in term of stimulation of the beneficial flora.

Many other non-digestible substances are only partially fermentable.

The recommended daily intake for dietary fibre varies between 25 and 30g in adults. Of this intake, two-thirds should be from insoluble dietary fibre sources and one-third from soluble sources.

Chicory inulin is a source of soluble dietary fibre. It means that its daily consumption may vary between 8 and 10g. At this realistic dosage, the side-effects of inulin are unlikely to occur.

Several peer-reviewed publications have shown that, at a normal level of consumption, chicory inulin is very well tolerated.

Fibruline and Fibrulose, inulin and oligofructose, have earned large scientific support as being the most researched prebiotic. Also the industry is in favour of these ingredients as a main constituent to promote gut health.

The reason why food manufacturers embrace inulin and oligofructose is simple: on top of its health promoting benefits, these ingredients are white, neutral in taste and do not effect the final product's texture, unless desired like (for which specific types exist). Its big popularity as a source of fibre and as low calorie sugar and fat replacer make it an ideal substrate. The use of inulin in more than 10 000 different food products since 1996 (Mintel GNPD, 2008) testifies its status as a leading nutrition and health promoting ingredient.

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- Caroline Mulkowski is with Cosucra Groupe Warcoings SA, Warcoing, Belgium.


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