The prevalence of overweight and obesity are increasing at an alarming rate, more than doubling between 1980 and 2014. According to the World Health Organization in 2016, at least 1.9 billion adults, 41 million children under 5 years and over 340 million children and adolescents aged 5 – 19 years worldwide are overweight or obese, including 39 percent school-age children in the U.S. (CDC 2017; WHO, 2018). With the rise in overweight and obesity comes a rise in obesity-related health problems, including exacerbation of elevated blood pressure, serum cholesterol, serum triglycerides, and insulin resistance, and increased risk for heart disease, stroke, and type 2 diabetes, as well as certain cancers. Americans may not fully appreciate the severity of the problem. According to the 2014 Gallup Health and Healthcare survey, while half of adults in the U.S. say they would like to lose weight, only one quarter are seriously trying to do so (Gallup, 2013).
The Balance Between Intake and Expenditure
Weight maintenance and prevention of overweight and obesity requires a lifelong balance between intake and expenditure. Intake is influenced by calories consumed, perception of and response to hunger and satiety, energy density of foods selected, and energy availability. Physical activity, thermogenesis, and fat oxidation define expenditure. The factors involved in managing intake can be viewed as part of a body weight management “ladder” whose rungs consist of appetite (measured using visual analogue scales for appetite, hunger, satiety, prospective intake), hormonal regulation of satiety (measured by GLP-1, PY, Ghrelin, GIP), energy intake (measured by observation, food diaries, dietary recalls), and body weight and composition.
Weight loss requires a negative balance between intake and expenditure. Calorie dilution can serve as one tool for reducing calorie density and therefore calories consumed. Partially replacing sugars and carbohydrates or fats in a food with the chicory root fibers inulin and/or oligofructose, for example, can reduce calories because chicory root fiber provides 1-1.5 kcal/g, compared to 4 kcal/g of sugars and carbohydrates and 9 kcals/g for fats. Evolving research also supports a role for inulin and oligofructose in appetite and satiety regulation.
Satiety and Weight Management
Fermentation of inulin and oligofructose takes place in the colon and generates the bioactive short-chain fatty acids (SCFAs) acetate, propionate, butyrate, and lactate; these SCFAs participate in a number of metabolic processes that may influence appetite and body weight (Byrne et al, 2015).
Short-term data suggest that chicory root fiber fermentation impacts the release of two of the peptides and gut hormones associated with satiety – GLP-1 (and its precursor proglucagon mRNA), which stimulates glucose-dependent insulin secretion, inhibits glucagon release, inhibits gastric emptying, and suppresses appetite directly in the brain; and PYY, which inhibits gastric emptying, bile acid secretion, and digestive enzyme secretion (Delzenne et al, 2005; Delzenne et al, 2010). Both GLP-1 and PYY are secreted by L-cells in the ileum and colon.
Additionally and independent of the positive influence of chicory root fibers on GLP-1 and PYY, SCFAs appear to cross the blood-brain barrier to suppress appetite. This mechanism might help explain the effects of chicory root fiber on food intake reduction (Frost et al, 2014; de Vadder et al 2014).
A Role for Chicory Root Fiber
Numerous animal and human studies demonstrate satiety effects of a 50:50 combination of inulin and oligofructose (Orafti®Synergy1 (SYN1)) or of oligofructose alone (Orafti®P95). Data in animals consistently show that consumption of a diet containing 10 percent SYN1 or P95 results in lower energy intake, less body weight gain, and less fat mass accumulation when compared to a standard diet.
Data from human studies suggest that calorie consumption goes down with regular intake of SYN1 or P95 for at least 2 weeks. A 2014 meta-analysis confirms that chicory root fiber increases self-reported feelings of satiety (Kellow et al, 2014). The meta-analysis includes three hallmark studies on chicory root fiber (Cani et al, 2006; Whelan et al, 2006; Cani et al, 2009). Cani and colleagues (2006) observed an increase in satiety among a group of normal weight adults consuming a 16g/d dose of oligofructose; this study supports the BENEO-Institute’s recommendation of 16 g/d oligofructose to reduce energy intake. A 16 g/d dose also has been associated with lower calorie intake and increases in GLP-1 and PYY (Cani et al, 2009; Verhoef et al, 2011).
Studies on overweight and obese adults support these findings. Parnell and Reimer (2009) administered 21 g/d P95 or placebo for 12 weeks to a group of 48 healthy, overweight adults. The oligofructose group experienced a weight loss of 1.1 kg, reduction of trunk fat mass, suppressed ghrelin, and increased PYY. McCann et al (2011) provided 36 overweight or obese men and women with 12 g/day SYN1 or a placebo for three weeks. Compared with the placebo, SYN1 significantly reduced energy intake in all subjects.
Pedersen et al (2013) evaluated escalating dosages of P95 that would suppress appetite without producing adverse gastrointestinal side effects. The 12 study subjects increased their daily dosage weekly over 5 weeks from 15 to 55 g/d. Hunger ratings decreased significantly at ≥25 g/day. PYY increased with increasing doses, energy intake trended downward, and gastrointestinal tolerance was good at all intake levels. In a study by Daud et al (2014), 22 overweight and obese subjects reported less hunger and motivation to eat during an 8-week trial of 30 g/day P95; PYY levels also rose.
Considering the body of evidence on adults, long-term supplementation with chicory root fiber – 16 g/d P95 or 12 g/day SYN1 – supports body weight management through a variety of mechanisms and may help reverse weight gain.
Use in Children and Adolescents
In overweight and obese youths, ongoing research suggests that inulin-type fructans reduce energy intake, promote weight loss, and support normal weight gain. Abrams et al (2007) documented smaller increases in the normal range BMI, BMI z-score, and total fat mass during pubertal growth in a group of adolescents taking a daily prebiotic supplement (8g Orafti®Synergy1/d), as compared to a control group. Studies in Canadian children and U.S. adolescents confirm the beneficial influence of chicory root fiber supplementation with 8 g/d SYN1 on body weight changes in overweight and obese children during growth (Hume et al, 2015; Nicolucci et al, 2015). After 16 weeks, subjective ratings of appetite and fullness improved, energy intake dropped by 100 calories, BMI and body fat mass went down, a marker for overweight- and obesity-related inflammation dropped, and beneficial Bacteroides species increased.
Evidence from human and animal studies demonstrates that a daily dose of 12 g Orafti®Synergy1 or 16 g Orafti®P95 positively affects satiety regulation and in particular energy intake. The mechanism behind is related to the saccarolytic fermentation process of the prebiotic chicory root fiber and generation of short chain fatty acids, and eventually other bacterial metabolites.