Perhaps one of the biggest consumer-health concerns is immune health, especially given the recent food-contamination scares. A recent study from the Nestlé research centre in Switzerland investigated the immune-modulating properties of a prebiotic mix of inulin and fructo-oligosaccharides (FOS) and protection against salmonella infection.1
Mice were supplemented with either FOS/inulin (FI) or a control diet for one week before given a suboptimal vaccination against salmonella. Then, four weeks after the inoculation, mice were infected with the salmonella virus. There was an enhanced immune response in the FI group when compared to placebo, as well as an improved survival rate for those infected with salmonella. The authors concluded, "Overall, the data suggest that a diet supplemented with FOS/inulin mix stimulates mucosal immunity and seems to improve efficacy of an oral vaccine."
Animal studies are well and good, but what about human trials? Older persons at risk of malnutrition were evaluated on the effect of oral nutritional supplementation with and without oligosaccharides on gut bacteriology, in particular the bifidogenic flora, and on immune function and inflammatory parameters.2
The study examined 70 community- dwelling elderly and/or nursing-home subjects (84 +/- seven years) either undernourished or at risk of undernutrition. For 12 weeks subjects were given a daily liquid supplement with and without oligosaccharides (OS, 1.3g/250ml).
Results showed that markers of inflammation at the genetic level (TNF-alpha mRNA and IL-6 mRNA) decreased in the OS group with no change in the control group. This study indicates older persons at risk of malnutrition may benefit from the addition of prebiotics to improve the low-level inflammatory processes.
It is rare to find dietary nutrients that provide a synergistic effect when included within one product formulation. Such is the case, however, when soy is combined with prebiotics to enhance soy's unique anti-osteoporotic effects. Soy has been of great interest in the fight against osteoporosis for many years due to its high phyto-oestrogen content. The isoflavone equol is one of the main metabolites that exerts a bone-sparing effect. Similarly, prebiotics have been shown to influence the absorption of minerals such as calcium that are important in bone metabolism and turnover.
A recent French study evaluated the bone-sparing effects of equol on ovariectomised rats in three ways: 1. through the diet; 2. by eliciting its endogenous production by modulating intestinal microflora by short-chain fructo-oligosaccharides (sc-FOS); or 3. with live microbial (Lactobacillus casei) together with daidzein, its precursor.
The three-month diet included six variations: a control diet (OVX), and the control diet supplemented with either genistein (G), or daidzein (D), or equol (E) at the level of 10mcg/g body weight/day. The remaining OVX rats were given daidzein at a dose of 10mcg/g body weight/day, simultaneously with short-chain FOS (D+FOS) or L casei (D+L).
Diets with G, D or E exhibited a bone-sparing effect, though the inclusion of FOS to the diet significantly raised efficiency of the daidzein-protective effect on both femoral bone mineral density (BMD) and mechanical properties. The effects of lactobacillus were similar, except that the increase in metaphyseal-BMD was not significant.3
The take-home message of the study was that the co-ingestion of prebiotics such as FOS significantly improves daidzein's protective effects on the skeleton. Human work to confirm these exciting findings is still needed.
Mark J Tallon, PhD, is chief science officer of NutriSciences, a London-based consultancy firm specialising in health-claim substantiation, product development and technical writing.
Are prebiotics the next weight-loss tool?
Prebiotics are riding on the success wave of dietary probiotics, and they also are looking for a slice of the weight-loss market. In a recent study from the University of Calgary, Canada, researchers examined the influence of a prebiotic (inulin) on weight gain following a control diet, high-protein, high-fibre or a combination of the two latter diets over a three-week period.1
Those following a diet containing inulin experienced the lowest plasma triglyceride and total cholesterol levels. Overall, combining high protein with a high-fibre diet increased glucagon-like peptide-1 (GLP-1) secretion in response to oral glucose, but did not improve glucose tolerance or lipid profiles more than the high-fibre diet alone. Further work in humans and the assessment of long-term weight management is needed to fully assess the use of prebiotics as an effective strategy for weight control. -MT
1. Reimer RA, Russell JC. Glucose tolerance, lipids, and GLP-1 secretion in JCR:LA-cp rats fed a high protein fiber diet. Obesity 2008;16(1):40-6.
Prebiotics for infant allergies
Infant and child nutrition is one of the fastest-growing segments in the nutrition market in 2008, and prebiotics has a role here as well. Belgium's Orafti is currently conducting a long-term study (completion in 2010) as part of the EU-funded EARNEST project to better understand the role of symbiotic-enhanced formulas and infant health.
Until most recently, research hasn't fully delved into real-world outcomes such as the incidence of infant infections following prebiotic supplementation. One such study assessed if a specific prebiotic mixture could have a preventive effect against infections during the first six months of life.1 In a randomised, double-blind, placebo-controlled trial, healthy term infants with a parental history of atopy (allergy-related illness) were fed formula either supplemented with prebiotics (8g/L scGOS/lcFOS) or with placebo (8g/L maltodextrin) hypo-allergenic formula.
Infants in the prebiotic group had fewer episodes and recurrences of all types of infections and fewer infections requiring antibiotic treatment. These data are some of the first to directly assess the influence of prebiotics on a valid endpoint that manufacturers can use to convince consumers of their application beyond just immune enhancers. -MT
1. Arslanoglu S, et al. Early supplementation of prebiotic oligosaccharides protects formula-fed infants against infections during the first 6 months of life. J Nutr 2007; 137(11):2420-4.
Prebiotics nothing new, says evolutionary hitchhiker
It would be a mistake to look at the science and health benefits emerging from clinical studies of prebiotics as a new discovery of some magic bullet. More correctly we are simply witnessing a rediscovery of the importance of the diversity of fibre in the human diet.
When we look into the archaeological record of west Texas, some 10,000 years ago, daily consumption was 10, 15 and more than 20g/day from desert plants such as agave, prickly pear, sotol and wild onions. Along the shores of the Sea of Galilee in modern-day Israel, a remarkably well-preserved collection of plant remains has been recovered from the 23,000-year-old archaeological site. This extraordinary window reveals a collection of 90,000 plant remains including small grass seeds, cereals, acorns, almonds, raspberries, grapes, wild fig, pistachios, and other fruits and berries.
The exciting science behind prebiotics coupled with the underlying biological reality that humans are still designed to ferment a large and diverse quantity of fibre (~50 to 90g/day, minimum), and that much of our health is tied to the maintenance of a healthy population of gut bacteria, should serve as a wake-up call for new therapeutic approaches to health. We need microbiologists jumping on Oprah's couch about the different types of fibre all Americans should be eating.
Even though humans evolved from nothing more than a run-of-the-mill large mammal on an open savannah of other large mammals, to something of a geological force in an evolutionary blink of an eye, we owe much of our current success as a species to these tiny micro-organisms. They require little more than a safe place to live and a steady flow of the quantity and diversity of fibre that they and their microbial ancestors evolved on.
Continuing to ignore our shared nutritional past with our tiny friends and adhering to the very humanlike notion that we are somehow separate from nature will only result in progression of many human diseases to levels that will require the medical community to seek new vernacular to describe the potential public-health hardships. Fibre anyone?
Jeff D Leach is the founder of Paleobiotics Lab, a research group that explores the evolution of diet and nutrition and its relevance to modern health and well-being. When he isn't out digging square holes at archaeological sites, Leach can be found in the French Quarter in New Orleans.
1. Benyacoub J, et al. Feeding a diet containing a fructooligosaccharide mix can enhance Salmonella vaccine efficacy in mice. J Nutr 2008;138(1):123-9.
2. Schiffrin EJ, et al. Systemic inflammatory markers in older persons: the effect of oral nutritional supplementation with prebiotics. J Nutr Health Aging 2007; 11(6):475-9.
3. Mathey J, et al. Modulation of soy isoflavones bioavailability and subsequent effects on bone health in ovariectomized rats: the case for equol. Osteoporos Int 2007;18(5):671-9.