Glucomannan

Table 5. Comparison of Glucomannan Compositions from Various Sources...

Only traces of mannose occur in the hydrolysates of some monocotyledon stems (7,9) although glucomannans occur in the tubers and leaves of some monocotyledon species (72). 

Both types of xyloglucans exhibit monolayer sorption onto cellulose (116) and tamarind xyloglucan exhibits maximum specific sorption onto cellulose less than that of coniferous xylan. By inference with other data, this is also less than that of glucomannan and hardwood xylan, but similar to many additives used in the paper industry. 

CeU waUs of woods contain other subgroups of hemiceUuloses, in particular those composed primarily of D-mannopyranosyl or D-galactopyranosyl units. Glucomannans [11078-31-2] comprise 3—5% of the wood of angiosperms and 3—12% of the wood of gymnosperms. Galactoglucomannans [9040-29-3] are also common. 

P-D-mannan with single 6-Unked a-D-galactose branches g 4)-p -D-glucomannan ... 

Glucomannans (GM) and galactoglucomannans (GGM), common constituents of plant cell walls, are the major hemicellulosic components of the secondary cell walls of softwoods, whereas in the secondary cell walls of hardwoods they occur in minor amounts. They are suggested to be present together with xylan and fucogalactoxyloglucan in the primary cell walls of higher plants [192]. These polysaccharides were extensively studied in the 1960s [6,193]. 

The main side effects of glucomannan include flatulence and stomach discomfort. Glucomannan may also expand in the esophagus (swallowing tube) and cause blockage if it is not taken with plenty of water. It can also interact with other medicines it should be taken separately from other medicines by at least a couple of hours. 

Fig. 1. Global symptom score in patients treated with glucomannan plus rifaximin and in patients treated with glucomannan plus placebo (from Papi et al. [45]).

Similar results were obtained in a large prospective open trial including 968 outpatients with symptomatic diverticular disease [44], Patients were randomly assigned to receive fiber supplementation (glucomannan 4 g/day) or fiber supplementation plus rifaximin (400 mg twice a day for 7 days every month) for 12 months. After 12 months, 56.5% of patients in the rifaximin group were symptom free compared to 29.2% of patients in the fiber supplementation only group (p < 0.001). 

Although there is some evidence for the efficacy of long-term treatment with rifaximin for symptomatic relief in patients with uncomplicated diverticular disease, an unresolved issue is whether rifaximin can prevent major inflammatory complications of diverticular disease. In the two prospective open trials discussed above, the occurrence rate of complications in 12 months was lower in patients treated with glucomannan plus rifaximin compared to patients treated with glucomannan only 2.7 versus 0.9% [43] and 3.2 versus 1.3% [44], This observation was not confirmed in the double-blind placebo-controlled trial [45] in which no difference in the 1-year complication rate was observed between the rifaximin and placebo groups. However, in all the studies, the number of patients suffering complications in a 12-month period was too small to detect any statistically significant... 

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