Flatulence can cause discomfort and distress but there are few published data of normal patterns and volumes. Twenty four hour collections were made using a rectal catheter in 10 normal volunteers taking their normal diet plus 200 g baked beans. Total daily volume ranged from 476 to 1491 ml (median 705 ml). Women and men (both n=5) expelled equivalent amounts. The median daily flatus hydrogen volume was 361 ml/24 h (range 42-1060) and the carbon dioxide volume 68 ml/24 h (range 25-116), three volunteers produced methane (3, 26, and 120 ml/24 h), and the remaining unidentified gas (presumably nitrogen) or gases contributed a median 213 ml/24 h (range 61-476). Larger volumes of flatus were produced after meals than at other times. Flatus produced at a faster rate tended to contain more fermentation gases. Flatus was produced during the sleeping period, but the rate was significantly lower than the daytime rate

Experiments were carried out in vitro and in normal human subjects to evaluate alternative food-grade viscous polysaccharides as agents for reducing postprandial hyperglycemia and to assess the relationship between the in vitro and in vivo performance of the polysaccharides. A 1:1 mixture of xanthan and locust bean gum (X/LBG) had the greatest viscosity at equivalent concentrations and shear rates and was more effective than guar gum, xanthan, or locust-bean gum at inhibiting glucose movement in vitro. It was not, however, more efficient in lowering postprandial blood glucose and plasma insulin in human subjects when incorporated in a drink containing 50 g glucose. When the different gums were acidified and reneutralized to mimic conditions in the gut, there was a better correlation between viscosity and blood glucose and plasma insulin levels. This effect may explain why X/LBG was no more effective than the other gums in reducing postprandial hyperglycemia in man.

No abstract

Starch that is resistant to human amylases forms during the cooking and subsequent cooling of some foods, and may therefore be a substrate for the bacterial flora of the colon. It is thus possible that resistant starch (RS) will affect colon function in a similar manner to non-starch polysaccharides. To test this theory, a group of eight volunteers took two diet supplements for 1 week each in a random order with a 1 week separation. One supplement comprised mainly 350 g Cornflakesld and the other 380 g Rice Krispiesld, providing 10.33 and 0.86 g RSjd respectively. The amounts of amylase-digestible starch, nonstarch polysaccharides, total carbohydrate, energy, protein and fat were balanced between the two periods by giving small amounts of Casilan, wheat bran, butter and boiled sweets. The volunteers made faecal collections during day 3 to day 7 of each period. Whole-gut transit time was calculated using the continuous method. Stool consistency and ease of defaecation were assessed by the volunteers. All episodes of flatulence noticed were recorded in a diary, along with food intake. Serial breath hydrogen measurements were made at 15 min intervals for 8 h on day 1 of each supplement. Questionnaires regarding colon function were completed at the end of each dietary period. There were no significant differences in the stool mass, frequency or consistency, ease of defaecations, transit time or flatulence experienced during the two supplements (P > 005). Significantly more H, (area under curve) was produced while eating Cornflakes than Rice Krispies (P < 0.05). The difference of 9.47 g RS/d between the two diets was over three times the calculated normal daily RS intake of 2.76g/d. As the only significant difference observed was in the breath H, excretion on day 1, we suggest that either RS is rapidly and completely fermented to end-products including H, gas, which is subsequently excreted via the lungs and has little influence on colon function, or that bacterial adaptation removed any observable effect on faecal mass and transit time by day 3.

1. Homogenized and diluted faeces (SO g/l) from one human source were incubated with the complex plant polysaccharide, guar gum, to investigate the degradation of viscous polysaccharides by intestinal bacteria.2. Incubation of the faecal homogenate with guar gum produced a rapid decrease in viscosity and in pH, accompanied by the release of hydrogen.3. No changes in viscosity or pH were observed and there was no production of H, gas when guar gum was incubated with autoclaved faecal homogenate (20 min, 1.03 x lo5 Pa). 4.A bacteria-free filtrate of faeces was prepared by centrifuging the faecal homogenate (2400 g for 100 min) followed by filtration through a Seitz filter and then a millipore filter (size 0.45 pm). Incubating this with guar gum produced a slow decrease in viscosity, but no significant change in pH and no generation of H,.5 . Our results show that guar gum can be fermented by human colonic bacteria and suggest the possibility of predigestion by extracellular free enzymes.