Small-intestinal digestion of partially resistant cornstarch in healthy subjects

The aims of this study were to measure the amount of starch from partially resistant starches (retrograded and complexed high-amylose cornstarches) escaping small-intestinal digestion in healthy humans by use of an intubation method and to compare these data with data obtained by indirect in vitro methods. Experiments were carried out in vivo in 6 healthy humans by using ileal intubation and stool analysis and in vitro by using 3 different methods for analyzing resistant starch. In intubated subjects, 51 +/- 2% of the retrograded and 21 +/- 2% of the complexed starch was delivered to the ileum and was fermented almost completely in the colon. In vitro estimates of the absorption of resistant starch were much lower. We conclude that technologically modified starches may substantially increase the amount of carbohydrate available for colonic fermentation in humans, but that in vitro measurements of resistant starch are inaccurate for predicting malabsorption in healthy humans.

Granisetron plus methylprednisolone for the control of high-dose cisplatin-induced emesis

This double-blind, double-dummy, randomized study compared the 24 h efficacy and safety of granisetron alone (3 mg i.v. over 30 s) or in combination with methylprednisolone (250 mg i.v. twice daily) in preventing nausea and vomiting in 308 patients (254 males) receiving high-dose cisplatin (100 mg/m2 or above) for mainly lung, and head and neck cancers. All patients received oral follow-on therapy comprising oral granisetron and methylprednisolone during the following 6 days. Primary efficacy variables were the proportions of complete responses (CR; no vomiting, no worse than mild nausea, no rescue and no withdrawal), no vomiting and no nausea over the first 24 h following initiation of the cisplatin infusion. The two treatment groups were well matched for demographics, cancer site, cisplatin dose and duration of infusion. Granisetron plus methylprednisolone was significantly more effective than granisetron alone for all primary efficacy variables: CR 78 versus 59% (p<0.001), no vomiting 80 versus 61% (p<0.001) and no nausea 74 versus 57% (p<0.002). Significantly more patients receiving the combination were free of any emetic symptoms (74 versus 54%, p<0.001). Significantly fewer patients receiving combination therapy also required rescue therapy with i.v. granisetron (12.2 versus 21.7%, p=0.026). During the follow-on period, complete response rates varied day by day from 50 to 71%. Both treatments were well tolerated, with constipation, abdominal pain and headache as the most frequent adverse events.

Symptomatic response to varying levels of fructo-oligosaccharides consumed occasionally or regularly

OBJECTIVE

To evaluate in 14 healthy volunteers the gastrointestinal tolerance to an indigestible bulking sweetener containing fructo-oligosaccharides (FOS).

DESIGN

In order to mimic their usual pattern of consumption, FOS were ingested throughout the day either occasionally (once a week, first period) or regularly (every day, second period). In the two patterns of consumption, daily sugar doses were increased until diarrhoea and/or a symptom graded 3 (i.e. severe) occurred, or when subjects did not want to ingest more candies.

SETTING

Clinical Nutrition Unit, Hôpital Saint-Lazare, Paris.

RESULTS

In both periods, the first symptom which occurred was excessive flatus (> 30 g FOS/day): borborygmi and bloating appeared at a higher level (> 40 g/day); lastly, abdominal cramps and diarrhoea occurred at a very much higher level (50 g/day). The volumes of hydrogen excreted in breath in response to the same load of FOS were not different between the two periods.

CONCLUSIONS

Chronic consumption of FOS initiated cautiously with subsequent gradual increase did not improve tolerance, nor reduce breath excretion of hydrogen.

Digestibility and bulking effect of ispaghula husks in healthy humans

The digestibility of ispaghula, a mucilage from Plantago ovata composed mainly of arabinoxylans, and its faecal bulking effect were studied in seven healthy volunteers who ingested a low fibre controlled diet plus either placebo or 18 g/day of ispaghula for two 15 day periods. Whole gut transit time and gas excretion in breath and flatus were not different during the periods of ispaghula and placebo ingestion. Faecal wet and dry weights rose significantly, however, during ispaghula ingestion. Faecal short chain fatty acid concentrations and the molar proportions of propionic and acetic acids also increased. Most of the ispaghula had reached the caecum four hours after ingestion in an intact highly polymerised form. During ispaghula ingestion, the increase in the faecal output of neutral sugars was accounted for by the faecal excretion of arabinose and xylose in an intact highly polymerised form; the apparent digestibilities of these sugars were 24 (11) and 53% (6) respectively (mean (SEM)). In conclusion, ispaghula is more resistant to fermentation than previously reported in humans, and its bulking effect largely results from intact material.

Gastrointestinal effects and energy value of polydextrose in healthy nonobese men

We studied seven healthy volunteers before and during acute (PD1) and chronic (PD2) ingestion of 30 g polydextrose (PD)/d. The energy value of PD was assessed after [U-14C]PD was added to the 10-g morning dose of PD during PD1 and at the end of PD2. Thirty-one +/- five percent (mean +/- SD) (PD1) and 29 +/- 4% (PD2) of the dose appeared in breath within 48 h. A small fraction of the ingested radioactivity was recovered in urine (4 +/- 1%) and excreted in flatus (< or = 1%) and in feces as volatile fatty acids (VFAs) (< 1%) and bacteria (3-4%); the remaining radioactivity in stools, 33 +/- 3% (PD1) and 32 +/- 4% (PD2), was assumed to be intact PD. Breath excretion of the label was 49 +/- 5% after intracolonic infusion of [U-14C] acetate. The energy value of PD, calculated by means of Miller and Wolin's stoichiometric equation of colonic fermentation, was similar during PD1 and PD2: 4.0 and 6.1 kJ/g, respectively, when breath 14CO2 and VFA production from PD were used for calculation.

Pyxigraphic sampling to enumerate methanogens and anaerobes in the right colon of healthy humans

BACKGROUND

A major limitation in studying the proximal human colonic flora is the lack of suitable sampling methods. The aim of this study was (1) to describe a prototype technique, pyxigraphy, which uses swallowed capsules containing a mechanism allowing the remote control of sampling the gastrointestinal tract contents, and (2) to use this sampling method to examine the distribution of methanogens in the colon of methane (CH4) excretors and non-CH4 excretors.

METHODS

In six CH4 excretors and four non-CH4 excretors, samples of the right colonic contents were obtained by means of the pyxigraphic sampling method. Methanogens and total anaerobes were enumerated in both the right colonic and fecal contents.

RESULTS

In CH4 excretors, the concentration of methanogens was higher in the feces than in the right colonic contents, representing 12% and 0.003%, respectively, of the total anacrobes (P < 0.02). In non-CH4 excretors, no difference was observed, methanogens representing < 0.003% of the total anaerobes in both the right colonic and fecal contents.

CONCLUSIONS

Pyxigraphy is a noninvasive, simple, and safe sampling method that allows to study the microbial populations of the proximal colon. The results obtained showed that methanogens preferentially colonize the distal part of the colon in CH4 excretors.

Can diarrhea induced by lactulose be reduced by prolonged ingestion of lactulose?

Twelve healthy volunteers were studied for two test periods, at the beginning of which they ingested a diarrheogenic load (60 g) of lactulose in 350 mL water with 10 g polyethylene glycol 4000 (PEG); the two periods were separated by a lactulose feeding period of 8 d, during which a nondiarrheogenic load (20 g) of lactulose was taken twice daily. The transit time and flow rates of water and lactulose in the distal ileum of four subjects were not different before and after the lactulose feeding period. In the other eight subjects, stool weight and frequency, fecal pH, and fecal outputs of carbohydrates and osmotic moieties after the ingestion of 60 g lactulose dropped significantly (P < 0.05) after the lactulose feeding period, whereas the orofecal transit time and fecal concentrations of beta-galactosidase and lactic acid increased (P < 0.05). We conclude that changes in colonic function induced by prolonged exposure to a nondiarrheogenic amount of lactulose mitigate the severity of the diarrhea because of the larger dose of lactulose.

Site and substrates for methane production in human colon

On two occasions separated by seven days, 22 g mucin (hog gastric mucin) was infused into right and left colon of 12 healthy volunteers (6 CH4 producers and 6 non-producers) maintained on a controlled diet. In the six CH4 producers, excess volumes of H2 excreted in breath were 73.4 +/- 11.9 and 35.1 +/- 14.1 (SE) ml/8 h (P less than 0.05) in response to right and left colonic infusion of mucin, respectively; excess volumes of CH4 were, respectively, 6.7 +/- 1.7 and 38.9 +/- 11.1 ml/8 h (P less than 0.05). In the six CH4 nonproducers, excess volumes of H2 excreted in breath were 76.6 +/- 17.6 and 30.8 +/- 6.3 ml/8 h (P less than 0.02) in response to right and left colonic infusion of mucin, respectively; excess volumes of CH4 were, respectively, 0.0 +/- 0.0 and 0.1 +/- 0.1 ml/8 h (not significant). In a further experiment, 17 healthy volunteers (10 CH4 producers and 7 nonproducers) were given on 2 consecutive days an oral load and an enema of 10 g lactulose. In the 10 CH4 producers, excess volumes of H2 excreted in breath were 74.6 +/- 15.1 and 32.3 +/- 11.5 ml/6 h (P less than 0.001) in response to oral ingestion and lactulose enema, respectively; excess volumes of CH4 were, respectively, 7.7 +/- 3.0 and 38.2 +/- 7.2 ml/6 h (P less than 0.001).(ABSTRACT TRUNCATED AT 250 WORDS)

Effect of chronic ingestion of a fermented dairy product containing Lactobacillus acidophilus and Bifidobacterium bifidum on metabolic activities of the colonic flora in humans

Nine healthy volunteers were studied before, during, and after ingesting a fermented dairy product containing Lactobacillus acidophilus, Bifidobacterium bifidum, and mesophilic cultures (Streptococcus lactis and S cremoris) for 3 wk. Hydrogen and methane productions and fecal beta-galactosidase and beta-glucosidase activities were measured as indicators of fermentation capacity of the colonic flora. Fecal concentrations of nitroreductase, azoreductase, and beta-glucuronidase, which may be implicated in colonic carcinogenesis, were also assessed. Hydrogen and methane productions, fecal beta-galactosidase, beta-glucuronidase, and azoreductase activities did not change over three 3-wk periods whereas fecal beta-glucosidase activity increased (42 +/- 6, 91 +/- 12, and 40 +/- 6 IU/g N, P less than 0.01) and nitroreductase decreased (0.87 +/- 0.13, 0.54 +/- 0.11, and 0.57 +/- 0.08 IU/g N, P less than 0.05).

Digestion and absorption in the human intestine of three sugar alcohols

The digestion and absorption of three sugar alcohols, consumed chronically in three identical daily postprandial doses, were evaluated in six volunteers during three 11-day periods. Each period included a 3-day adaptation period during which sugar alcohol doses were increased, a 4-day equilibration period, a 2-day stool collection period, and a 2-day intubation period. From day 4, the daily administered amounts were either 30 g pure sorbitol, 57 g maltitol containing 30 g sorbitol, or 69 g Lycasin 80/55 (Roquette, Lestrem, France), which is a hydrogenated glucose syrup also containing 30 g sorbitol. The distal ileal output of sugar alcohols and their components was determined by aspiration after a single meal. The mean percentage of sorbitol absorbed in the small intestine was significantly higher in pure sorbitol doses than in those containing maltitol and Lycasin 80/55 (79% +/- 4% vs. 64% +/- 4% and 64% +/- 5%, mean +/- SEM). The mean percentage of total maltitol digested was not different for pure maltitol and maltitol contained in Lycasin 80/55 (90% +/- 2% vs. 86% +/- 2%). Stool excretion of sugar alcohols was negligible, indicating that the sugar alcohols reaching the colon were almost completely digested by the colonic flora. The mean estimated energy values of the sugar alcohols ingested in kcal/g were 3.58 +/- 0.08 for sorbitol, about 3.50 +/- 0.07 for maltitol, and between 3.11 +/- 0.08 and 3.54 +/- 0.08 for Lycasin 80/55. Because the experimental conditions of this study mimicked the usual way of consumption of the three sugar alcohols, little calorie saving can be expected from the chronic consumption of these sugar alcohols in so-called sugar-free products.

Comparative study of hydrogen and methane production in the human colon using caecal and faecal homogenates

Rates of hydrogen and methane production were compared in caecal and faecal homogenates in six methane producers. Faecal homogenates produced hydrogen and methane in the absence of and after the addition of lactulose, whereas caecal homogenates produced hydrogen but little methane.