04 October 2006

Prebiotics could curb obesity

The prebiotics inulin and oligofructose could offer ways of stemming the tide of obesity, or could change immune responses and protect against potentially harmful infections.

The prebiotics inulin and oligofructose could offer ways of stemming the tide of obesity, or could change immune responses and protect against potentially harmful infection, said prebiotic experts at Orafti’s 5th Research Conference at Harvard Medical School last week.

The growing body of science in these areas looks set to open up new areas to apply prebiotics, with Orafti’s Beneo range leading the way with the quantity of science into the potential health effects.

More potential benefits identified
Prebiotics are non-digestible food products that stimulate the growth of "good" bacteria (probiotics) already present in the colon. In other words, prebiotics act as food for probiotics.

Two fructo-oligosaccharide compounds have, in recent years, emerged as having very important prebiotic properties. These compounds, called inulin and oligofructose, contain substrates that nourish the beneficial micro-organisms in the gut.

Considerable research has already focused on the role of inulin and oligofructose in bone health and colorectal cancer, and the science is now expanding in ever-increasing circles to cover potential benefits for the immune system, weight management, and intestinal health.

Belgium’s Orafti has been influential in building the science behind inulin and oligofructose, and their 5th Research Conference in Boston last week allowed researchers to present old and new data concerning the role of the prebiotics for these new areas of interest.

The research focused on inulin (beta (2,1) linear fructans), oligofructose (the partially hydrolysed product of inulin), or mixtures of the two, most notably Orafti’s Synergy1, a specially formulated oligofructose-enriched inulin from chicory.

Satiety, weight management and diabetes
With increasingly worrying statistics of the prevalence of overweight and obese sections of the general population, more and more interest is targeting appetite suppressors or satiety nutrients as a way of aiding weight control.

The potential role of inulin and oligofructose in satiety and weight management is an area that Orafti sees as very important, said Dr Anne Franck, Orafti’s executive vice president, science and technology.

“It is the responsibility of the food industry to bring to consumers foods to control weight,” she told

Initial results from animal studies have shown that inulin and oligofructose-fed animals have lower fat mass.

This is linked to the increased levels of a gut-brain hormone called glucagon-like peptide one (GLP-1), which boosts glucose-stimulated insulin secretion.

Nathalie Delzenne from the Catholic University of Louvain, Belgium, in collaboration with Rémy Burcelin from Rangueil Hospital in Toulouse, showed data from animal studies of high-fat fed diabetic mice supplemented with inulin and oligofructose for four weeks with or without a GLP-1 receptor blocker (exendin 9-39, Ex-9).

By blocking the GLP-1 receptor, the beneficial effects of the prebiotics on glucose tolerance, blood glucose levels, weight gain, and insulin-secretion, prebiotics were interrupted by the administration of Ex-9.

Further experiments with mice genetically engineered to have the GLP-1 receptor inactivated were totally insensitive to the beneficial role of inulin and oligofructose.

“These findings highlight the potential interest of enhancing endogenous GLP-1 secretion by inulin-type fructans for the prevention and/or treatment of obesity and type-2 diabetes,” said Delzenne.

“Research data in humans are still scarce but recent human intervention studies showed promising first evidence for an impact of inulin-type fructans on satiety and food intake regulation,” said Prof Furio Brighenti from the University of Parma's Department of Public Health.

Indeed, three human studies have been performed to date with 33, 10 and 11 participants, respectively. All three studies reported effects of inulin and oligofructose on energy intake and the sensation of fullness.

“There have been three human studies on satiety, and all three have shown a significant effect,” said a very optimistic Dr Douwina Bosscher, from Orafti.

Professor Glenn Gibson from the University of Reading who first coined the term ‘prebiotic’ with Marcel Roberfroid from the Catholic University of Louvain (J. Nutr. 1995, Vol. 125, pp. 1401-1412) sounded a note of caution, however, telling this website that satiety may be a “tricky marketing thing” and that some consumers may see it as a “quick-fix approach.”

The real answer to obesity, he said, was to eat less and exercise more.

Dr Franck confirmed that this was an area of research where Orafti was determined to do more and said that a big human intervention study was planned to start very soon.

Immune modulation by prebiotics
“The science of immune modulation is in it’s infancy,” Dr Franck told

Despite being early days for the possible benefits in this area, a number of studies have already been published that show a significant effect of prebiotics in human health. Such an effect is due to impact non-digestible carbohydrates like inulin and oligofructose on metabolic functions in the intestine, which in turn impact on local immune cells in this area, and particularly on the gut-associated lymphoid-tissue, which plays a role in the immune system.

Most of the data in this area comes from rats and mice, but Dr Bernhard Watzl from the German Federal Research Centre for Nutrition and Food presented unpublished data from a pig study, an animal with an intestinal tract similar to humans. The pigs were supplemented short-term (three weeks) and long-term (three months) with inulin and oligofructose (Synergy1) and markers of immune function were measured in a variety of gut immune tissues.

Watzl told the 160 attendees at the conference that short-term supplementation resulted in increased phagocytic activity of white blood cells and increased numbers of so-called natural killer T-cells (NKT-cells) in the spleen.

“In the long-term experiment, the prebiotic enhanced NK cell activity in Peyer’s patches [part of the lymphatic system] and splenocytes [a white blood cell found in the spleen], overall suggesting a boost of innate immunity not only systematically but also locally in the gut,” he said.

Additional research has shown that prebiotics may also improve the response to a vaccination, including a study with young children and the measles vaccination. Dr Franck also told this website that a human study looking at the effects of Orafti prebiotics with flu vaccines was set to begin.

Inflammatory intestinal conditions
Inflammatory bowel disease (IBD) and irritable bowel syndrome (IBS) are chronic inflammatory conditions of the intestine that affect about 0,5 percent of the populations in the Western World. Well-established science has shown that the diseases arise in some people due to a lack of tolerance to gut bacteria. It is no wonder therefore that prebiotics have emerged as an interesting avenue of study for these diseases and conditions.

Dr Levinus Dieleman from the University of Alberta in Canada told attendees that studies have shown that a combination of inulin and oligofructose (Synergy1) was effective in preventing the development of colitis in animals and, when given in combination with probiotics, reduced the level of inflammation in a small human trial.

The positive effects seen in these experiments were associated with decreased levels of pro-inflammatory cytokines and increased levels of anti-inflammatory cytokines.

A small human study in people with Crohn’s disease reported that people receiving a daily supplement of 15g of inulin-type fructans (Prebio1) had reduced disease activity.

These studies, said Dr Franck, provided “very nice data” for the potential of prebiotics in inflammatory intestinal conditions.

Prof Allan Walker from Harvard Medical School told that he was “very impressed” with the results of the IBD studies. Walker said that he sees the role of prebiotics as a way of maintaining intestinal health, rather than as a treatment of IBD. He said immune suppressors should be used to get the diseases and conditions under control, and then maintain this, using prebiotics. - (Decision News Media, October 2006)

Read more:
Feed your tummy bugs
Pre- and probiotics boost immunity


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