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Gastrointestinal tolerance and utilization of agave inulin by healthy adults

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Abstract

Little clinical research exists on agave inulin as a fiber source. Due to differences in botanical origin and chemical structure compared to other inulin-type fibers, research is needed to assess gastrointestinal (GI) tolerance following consumption. This study aimed to evaluate GI tolerance and utilization of 5.0 and 7.5 g per day of agave inulin in healthy adults (n = 29) using a randomized, double-blind, placebo-controlled crossover trial consisting of three 21 day periods with 1 week washouts among periods. GI tolerance was assessed via daily and weekly questionnaires, three fecal samples were collected on days 16-20 of each period, and breath hydrogen testing was completed on the final day of each treatment period. Survey data were compared using a generalized linear mixed model. All other outcomes were analyzed using a mixed linear model with a repeated measures procedure. Composite GI intolerance scores for 5.0 and 7.5 g treatments were both greater (P < 0.05) than control, however, scores were low, with means of 0.4, 1.9, and 2.3 on a 0-12 point composite scale for 0, 5.0, and 7.5 g treatments, respectively. There were slight increases (P < 0.05) in bloating, flatulence, and rumbling frequency with 5.0 and 7.5 g agave inulin. Abdominal pain and rumbling intensity were marginally greater (P < 0.05) with 7.5 g. Bloating and flatulence intensity increased (P < 0.05) with 5.0 g and 7.5 g. Agave inulin did not affect diarrhea (P > 0.05). Number of bowel movements per day increased, stools were softer, and stool dry matter percentage was lower with 7.5 g (P < 0.05). Breath hydrogen concentrations increased (P < 0.001) from 5-8 hour postprandial when participants consumed agave inulin compared to control. These data demonstrate that doses up to 7.5 g per day of agave inulin led to minimal GI upset, do not increase diarrhea, and improve laxation in healthy young adults.
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... Three participants were added to compensate for a potential 20% dropout rate [17,18]. Additionally, considering published GI tolerability trials with similar prebiotics, dietary, or functional fibers [19][20][21][22][23] and high interindividual variability in GI tolerance previously reported for agave inulin [16], an additional 8 subjects per group were considered reaching n = 25. Nevertheless, after months of enrollment, very few volunteers for the lean healthy group responded, and even fewer participants met the inclusion criteria. ...
... We found that every agavins dose induced a significant difference in daily ratings for the five GI symptoms herein evaluated in lean participants compared to placebo controls, except for abdominal pain at 7 g/day. Contrarily, a previous study in healthy adults receiving 5 g/day of agavins (agave fructans), which is one of the doses we tested, reported no significant change in abdominal pain after three weeks of intervention, but a significant increase in intestinal bloating producing a mild to moderate effect compared with placebo, while others have also found an increment in bloating with the same dose in healthy young adults [16,27], corresponding to a mild effect in accordance to what we observed for agavins; however we also found a significant increment in bloating scores for obese patients consuming 5 g/day of agavins, equally to lean volunteers. ...
... Although an ambiguous term, bloating refers to a subjective sensation related to abdominal distension, considered as one of the dominant adverse effects in relation to dietary fiber intake, along with flatulence, abdominal cramps, and diarrhea [34,35], thus a mild effect detected for a dose of 5 g/day reflects a tolerable adaptation to agavins consumption. At higher doses, previously 7.5 g/day of agave fructans led to a greater daily and weekly score of flatulence, bloating, and rumblings than the control, but with a very mild effect [16]. With a similar dose (7 g/day), we found an increment in records of all evaluated GI symptoms compared to placebo in the obese-agavins group, as well as for the lean-agavins group, only excluding abdominal pain, which registered no differences. ...
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... Stool frequency was measured in 20 ITF studies and was increased in 11 studies (27, 29, 34, 43, 47, 53, 73-75, 77, 78) but not in 9 other studies (18,20,32,33,40,54,72,76,82). Further, there was no change in stool (18,20,33,40,47,51,54,72,81), though stool consistency became harder in 1 study (73) and softer in 4 studies (43,74,75,77). The most commonly reported measures of tolerance were flatulence, breath H 2 gas, stool frequency, stool consistency, bloating, abdominal pain, and transit times. ...
... Only 3 reported no change in VAS scores for flatulence with consumption of 8.1 g/d of inulin (71) and 11 g/d of inulin (66,67). Severity scores of abdominal pain were correlated with the ITF dose, with higher dosages resulting in higher reported severity scores (77). Participants in 5 studies reported an increase in severity scores for abdominal pain after consuming an ITF (27,35,42,76,77,82), 2 studies reported no changes in scores (18,33), and 1 study reported a 52% reduction in abdominal sensation after consuming inulin (8 g/d) (20). ...
... Severity scores of abdominal pain were correlated with the ITF dose, with higher dosages resulting in higher reported severity scores (77). Participants in 5 studies reported an increase in severity scores for abdominal pain after consuming an ITF (27,35,42,76,77,82), 2 studies reported no changes in scores (18,33), and 1 study reported a 52% reduction in abdominal sensation after consuming inulin (8 g/d) (20). There were statistically significant increases in severity scores of bloating in 12 studies (32,33,35,45,50,51,59,72,74,76,77,80) and no change in 3 studies (18,27,40). ...
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... Through intestinal fermentation, soluble dietary fibers with a reduced degree of viscosity (pectins and fructo-oligosaccharides) promote the production of SCFAs, including acetic, propionic and butyric, as well as carboxylic acids, such as lactic acid [37,38]. SCFAs have been found to operate as signaling molecules by binding to the FFA2, FFA3, GPR109a and Olfr78 membrane receptors in the intestine [39,40]. ...
... Through intestinal fermentation, soluble dietary fibers with a reduced degree of viscosity (pectins and fructo-oligosaccharides) promote the production of SCFAs, including acetic, propionic and butyric, as well as carboxylic acids, such as lactic acid [37,38]. SCFAs have been found to operate as signaling molecules by binding to the FFA2, FFA3, GPR109a and Olfr78 membrane receptors in the intestine [39,40]. ...
... An in vitro study has demonstrated the degradation of inulin by F. prausnitzii, and ingestion of a diet containing inulin-type fructan increased the abundance of F. prausnitzii in the human gut (Duncan et al., 2002;Ramirez-Farias et al., 2008;Dewulf et al., 2013;Moens and De Vuyst, 2017). Furthermore, increased butyrate production by consuming an inulin-rich diet has been observed in a mouse model, and increasing evidence support the effect of inulin on intestinal health in various in vivo models (Campbell et al., 1997;Koleva et al., 2012;Holscher et al., 2014). However, despite considerable interest in the role of F. prausnitzii as an efficient degrader of inulin and the subsequent effect on improving intestinal health, molecular-level studies to determine the mechanisms whereby F. prausnitzii utilizes dietary inulin and undergoes physiological changes are still insufficient. ...
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