Digestive health is important to consumers. In a U.S. survey, 61 percent of consumers reported concern about maintaining digestive health and 43 percent were actively looking for products with natural ingredients to support that goal.
Is Constipation Common?
Many people experience bowel irregularity and constipation. Although individuals may define it in different ways, constipation can be described as fewer than three bowel movements a week and/or hard, dry and small bowel movements that are painful or difficult to pass (NIDDK). Constipation affects individuals of all ages. A seven-country survey found that more than one in five women in the U.S. and nearly one in six men described themselves as constipated (Wald et al, 2008). Between 2006 and 2011, constipation-related visits to emergency rooms by infants, children and adults across the U.S. rose 41.5 percent and mean cost per patient rose 56.4 percent (Sommers et al, 2015). Constipation can negatively influence feelings of well-being and quality of life.
The Role of the Colon
The large intestine, or colon, plays a major role in the regularity of bowel movements. Chyme moves from the small intestine into the colon in the final absorptive stage prior to elimination. Two major processes lead to production of feces from chyme: re-absorption of water and bacterial breakdown of fermentable undigested food residues. During re- absorption, up to 2 liters of chyme become concentrated into 0.5 liters of stool. The fermentation by bacteria of carbohydrates, primarily specific fibers, to generate short-chain fatty acids (SCFAs) is considered beneficial and desirable. Any undigested compounds that remain after fermentation, along with water and bacterial biomass, are excreted as a bowel movement. Adequate dietary fiber helps promote regularity, but the functionality of individual fibers need to be scientifically proven as not all fibers are the same.
Fiber and the Microbiome
Certain types of fiber, including the inulin-type fructans from inulin and oligofructose from chicory root, resist digestion in the small intestine, reach the large intestine virtually intact, and are metabolized by bacteria in the colon. Functioning as prebiotics, the non-digestible carbohydrates inulin and oligofructose selectively stimulate the growth and/or activity of beneficial bacteria such as bifidobacteria (Kleessen et al, 1997; Bouhnik et al, 2004; Kolida et al, 2007; Marteau et al, 2011; Mendlik et al, 2012) and lactobacilli (Ten Bruggengate et al, 2006), thus improving the health of the microbiome and contributing to normobiosis. (The opposite condition, dysbiosis, occurs when the microbiome is dominated by one or more potentially harmful bacterial species.) Other types of fiber are not used as feed for the microbiota to any significant degree and are excreted as such.
Chicory Root Fiber and Colon Function
Inulin and oligofructose catalyze both chemical and mechanical changes that enhance colon motility. Bifidobacteria and other beneficial bacteria are nourished by these fibers and selectively ferment them into SCFAs, including butyrate and acetaldehyde (De Preter et al, 2013). The presence of chicory root fiber (inulin, oligofructose) and the results of the prebiotic fermentation, SCFAs, in the large intestine contributes to softening by encouraging water binding in the stool and stimulates peristaltic muscle contraction. This leads to a slight increase in stool frequency per week, relief of mild constipation, increase in stool weight, and improvements in stool consistency, that is, softening. A meta-analysis of five studies involving 252 subjects showed significant effects on stool frequency, consistency, and transit time (Collado Yurrita L, et al, 2014).
Effects of inulin and oligofructose on stool frequency are well-documented in over two dozen studies on adults, older adults, and children, with effects resulting from a dosage of at least 3 g/day (Isakov et al 2013). Gibson et al. (1995) demonstrated that 15 g/day of oligofructose or inulin significantly increased stool frequency from 5.7 to 7.4 weekly bowel movements in healthy individuals. Stool weight went up 1.2 g and 2.1 g per gram of oligofructose or inulin, respectively. Later studies support the mild effects of inulin-type fructans on stool frequency, leading to more regular bowel movements among both healthy (Brighenti et al., 1999; Menne et al., 2000; Scholtens et al., 2006) and constipated (Kleessen et al, 1997; den Hond et al, 2000; Marteau et al, 2011) individuals. Effects on regularity do not appear to result from changes in transit time (Gibson et al., 1995; Causey et al., 2000; van Dokkum et al., 1999; Den Hond et al., 2000).
The increased biomass that results from exposure to inulin and oligofructose adds bulk to the fecal mass (Gibson et al, 1995; Castiglia-Delavaud et al, 1998; Den Hond et al., 2000; Van Dokkum et al., 1999; Scholtens et al., 2006 ). Furthermore, the higher water content of the biomass increases moisture in the stool and acts as a softening agent (Mendlik et al, 2012). As a result, excretion is facilitated.
Oligofructose also may aid those at risk of developing diarrhea. Cummings et al. (2001) provided a small group of healthy individuals at risk for travelers’ diarrhea with 10 g/day of oligofructose. The travelers taking oligofructose experienced a small but significant increase in frequency of bowel movements, a decrease in incidence of diarrhea (not significant), and significantly improved feelings of well-being.
Benefits to Infants and Children
Breast-fed infants have loose stools due to the human milk oligosaccharides (undigestible carbohydrates). When analyzing the microbiota composition, bifidobacteria are the dominating microorganisms. Prebiotics (Oligofructose (FOS), Orafti®Synergy1, GOS) are added to bottle-fed formula for infants to get the physiological effects of that formula closer to that of breast-fed children. In a randomized, double-blind, placebo-controlled trial on 56 infants under one year of age, Moore et al. (2003) observed an increase in stool frequency from 1.58 to 1.99 times per day and a softened stool consistency after feeding between 0.75 and 3g/day of oligofructose or control (maltodextrin) over 4 weeks. Supplementation of an average of 1.1 g/day oligofructose decreased constipation in a group of 123 infants and toddlers ages 4-24 months (Saavedra, 2002). A group of 35 infants and toddlers receiving 2 g/day oligofructose as part of a randomized, double-blind, placebo-controlled intervention study experienced significantly less flatulence and diarrhea (Waligora-Dupriet et al, 2007).
Desirable changes in stool consistency also were observed in a group of 2-5 year-old children with functional constipation (Escribano et al, 2015). Closa et al (2013) studied the effect of Orafti®Synergy1 (oligofructose-enriched inulin) provided in infant formula (0.8g/dL) in infants during the first 4 months of life in a double-blind, randomized, placebo-controlled and parallel trial with 124 control (Maltodextrin), 128 Orafti®Synergy1 fed infants and 131 infants that were breast-fed. The safe use of oligofructose-enriched inulin was clearly demonstrated in this study. The Syn1 infants showed a microbiota composition closer to breast-fed infants, softer stools and a higher stool frequency compared to controls, positioning the babies closer to breast-fed babies in their digestive health parameters.
Global Acceptance of the Relationship Between Chicory Root Fiber and Supporting a Normal Bowel Function
Inulin and oligofructose support digestive health, i.e. they support normal bowel function by increasing stool frequency per week, by providing relief in constipated people, by softening stools and providing higher stool weight. The dosage of inulin and oligofructose associated with digestive health varies with individual differences and subjective perception of digestive health and gastrointestinal tolerance. In human intervention studies intake amounts vary between 40g/d and 3g/d. Overall it can be concluded that a daily intake of approximately 8g/d taken in various occasions during the day (e.g. 2 g per serving) will support normal bowel function. In addition to their relationship with gastrointestinal health, inulin-type fructans can help fill in the fiber gap in the U.S., with few Americans meeting the recommendations of 31 grams per day for adult men and 25 grams per day for women (Dietary Guidelines for Americans, 2015-2020).