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Department of Clinical Nutrition, Institute of Internal Medicine, Göteborg University, SE 413 45 Göteborg, Sweden
2To whom correspondence should be addressed.
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ABSTRACT |
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 TOP ABSTRACT INTRODUCTIONInulin and oligofructoseOther dietary fiber studies...CONCLUSIONREFERENCES |
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KEY WORDS: • oligofructose • cholesterol • nitrogen • zinc • iron • humans
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INTRODUCTION |
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TOPABSTRACTINTRODUCTIONInulin and oligofructoseOther dietary fiber studies...CONCLUSIONREFERENCES |
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) and five earlier studies using
different high fiber products or diets (Bosaeus and Andersson 1987
, Bosaeus et al. 1992
, Ellegård and Bosaeus 1991
, Langkilde et al. 1993
, Lia et al. 1995
). |
Inulin and oligofructose |
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TOPABSTRACTINTRODUCTIONInulin and oligofructoseOther dietary fiber studies...CONCLUSIONREFERENCES |
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performed a double blind crossover study
with inulin and oligofructose in 10 patients with conventional
ileostomy due to ulcerative colitis. The mean serum cholesterol of the
subjects was 6.3 mmol/L. Subjects test diets were prepared in a
metabolic kitchen for 3 d. The basal diet with added sucrose (7 g)
compared with a diet fortified with of 17 g of inulin,
(19.4 g of Raftiline ST) or 17 g of oligofructose (19 g of
Raftilose P95). Inulin and oligofructose were digested only to a small
extent in the small intestine. The recovery in the ileostomy effluent
amounted to 88% [95% confidence interval (CI), 76–100%] and 89%
(64–114%) for inulin and oligofructose, respectively. Similar figures
have been reported (Bach Knudsen and Hessov 1995
) and
are comparable to the recovery of 88% obtained with wheat bran in our
earlier ileostomy studies (Sandberg et al. 1981
). The
nondigested fructans increased dry matter excretion by nearly 15 g, with an energy content of almost 17 kJ/g, equivalent to the energy
value of carbohydrates. No change in the mean daily ileal excretion of
nitrogen (2.2, 2.3 and 2.2 g), fat (8.7, 9.6 and 9.3 mmol), or
starch (8.8, 9.1 and 8.6 g) occurred in subjects fed the three
diets. Moreover, the mean values for the ileal excretion of calcium,
magnesium and zinc did not differ among dietary treatments. Mean
mineral excretions were 29.3, 29.8 and 31.2 mmol of calcium, 11.1, 10.9
and 10.8 mmol of magnesium and 119, 147 and 116 µmol of
zinc per 24 h, respectively. The ileostomy model offers a
sensitive method to determine short-term excretion of cholesterol,
which averaged 506, 504 and 510 mg per 24 h for the three diets,
respectively, and the mean cholesterol absorption, measured with an
isotope-labeled cholesterol technique, which averaged 63, 60 and 62%,
respectively. No significant differences in bile acid excretion between
the three periods were detected (480 mg, 453 mg and 326 mg,
respectively). This study suggests that inulin has little or no
influence on the absorption of nutrients and minerals in the small
bowel. Nevertheless, several questions about this study emerged,
including the following: How reliable are these figures? It must be
questioned whether the recovery from the ileostomy bags corresponds to
the flow from the small to the large bowel. Earlier experience of the
sensitivity of excretion figures for sterols in the ileostomy model may
provide some clues. |
Other dietary fiber studies with the ileostomy model |
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TOPABSTRACTINTRODUCTIONInulin and oligofructoseOther dietary fiber studies...CONCLUSIONREFERENCES |
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), reliable results of specific
analyses of the ileostomy contents could not be obtained until we
introduced studies using a controlled diet in the late 1970s that
minimized bacterial degradation by frequent collection and immediately
freezing of the contents. This is now referred to as the ileostomy
model. Advantages and disadvantages have recently been reviewed
(Andersson 1992
, Andersson and Bosaeus 1993
).
The main advantage of the ileostomy model is that the intestinal
transit time is so short that the effluent corresponding to one day's
intake is completely excreted before the next morning (Englyst and Cummings 1986
, Sandberg et al. 1981
). The
within-patient, within-diet and day-to-day variations are small,
making short-term balance studies feasible. The standard error of
the mean for nitrogen and calcium cumulative balances, was similar for
a 4-d balance period in ileostomy subjects (1.5 and 1.0 mmol/24 h,
respectively) compared with that for 52 d in subjects with an
intact large bowel (1.5 and 1.9 mmol/24 h, respectively)
(Tornquist et al. 1986
). The CV between days for dry
matter excretion in ileostomy subjects is ~5% (Ellegård and Bosaeus 1991
).
Collection of ileostomy contents is relatively easy to perform for
ileostomy subjects because handling of ileostomy excreta is a routine
matter for these subjects. In contrast, constant supervision and
encouragement are needed to obtain complete fecal collections from
normal healthy persons. The ileostomy model could be criticized because
ileostomy subjects have lost the ileocecal valve together with a
minimal part of the distal ileum. Furthermore, the bacterial flora
differ from those of the normal distal ileum. The number of bacteria in
the terminal ileum of ileostomy subjects has been estimated to be
107–108 per gram compared
with 105–106 per gram in
the normal ileum (Finegold et al. 1970
).
A number of studies, however, support the idea that there is only a
small microbial degradation in the ileostomy bags when they are handled
properly. Thus, degradation of bile acids and neutral steroids is
minimal (Bosaeus et al. 1986
, Bosaeus and Andersson 1987
). Furthermore, there is no or minimal
degradation of non-starch polysaccharide (NSP) components from
pectin, bran or starchy foods (Englyst and Cummings 1987
, Englyst and Kingman 1990
, Schweizer et al. 1990
). Less then 5 mmol/L of short-chain fatty acids
are found in ileal samples (Cummings and Englyst 1991
).
The pH of the ileostomy content is generally in the range of 7–8.
Moreover, to determine whether significant fermentation occurs in the
terminal ileum, two ileostomy subjects have been studied both with and
without the antibiotic Metronidazole (Englyst and Cummings 1987
). No significant difference was observed in the recovery
of non-starch polysaccharides (NSP), starch or resistant starch
with or without the antibiotic. Consequently, the ileostomy model can
be used for determination of small-intestinal digestion of
carbohydrates without interference from any substantial bacteriological
degradation.
It could also be questioned whether the transit through the small bowel
in the proctocolectomized subject differs from that of the
normalsubject. However, transit time through the stomach and small
intestine of ileostomy subjects is similar to that observed in healthy
subjects (Holgate and Read 1983
, Malagelada et al. 1984
). Moreover, the so-called ileal brake, whereby fat
in the terminal ileum may influence gastric emptying rate and the
intestinal transit time, also seems to be operative in ileostomy
subjects (Soper et al. 1990
).
The function of the distal ileum seems to remain intact in patients in
whom there is only a small resection of the distal ileum, as after
proctocolectomy for ulcerative colitis. Ileal excretion from patients
operated for Crohn's disease does not reflect the normal excretion to
the large bowel. The excretion of bile acids from the ileostomy is
seldom increased above 1 g/24 h. Bile acid excretion was found to be
410 ± 72 (mean ±SEM) mg/24 h in a
well-controlled group of nine ileostomy subjects (Ellegård and Bosaeus 1991
), which equals fecal losses. These nine
subjects had a mean serum cholesterol level of 6.0 mmol/l, within the
normal range of healthy subjects consuming a Western diet.
Two studies have also been performed to show that there is no
difference between the immediate response to a diet change on ileal
excretion and to the excretion pattern after some weeks of consuming
the same diet (Zhang et al. 1991
, Zhang et al. 1992
). The immediate response to the diet appears thus to
remain in long-term studies. Moreover, the reduction in serum
cholesterol induced by oat bran in ileostomy subjects was similar to
that of normal persons (Andersson and Bosaeus 1993
).
Earlier studies in ileostomy subjects have shown a correlation between
the serum cholesterol–lowering property of a dietary fiber product and
small bowel excretion (Andersson 1992
). Citrus pectin
(Bosaeus et al. 1986
) and oat bran (Lia et al. 1995
), which are known to reduce serum cholesterol, increased
ileal bile acid excretion. Wheat bran, without effect on serum lipids,
did not induce any significant change in sterol excretion
(Bosaeus et al. 1986
). Ileostomy studies with 3 d
for each dietary period, with the same number of subjects, given
15 g pectin or 15 g of mixed dietary fibers from unrefined
food, could detect changes in sterol excretion of 15%
(Andersson and Bosaeus 1993
). It seems unlikely that
inulin and oligofructose in similar doses (Ellegård et al. 1997
) would induce any considerable effect on sterol excretion
from the small bowel.
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CONCLUSION |
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TOPABSTRACTINTRODUCTIONInulin and oligofructoseOther dietary fiber studies...CONCLUSIONREFERENCES |
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), in relation to our
earlier experience with ileostomy subjects, three conclusions can be
reached. First, inulin or oligofructose passes through the small bowel
without degradation and without influencing the absorption of nutrients
or minerals (calcium, magnesium and zinc). Second, inulin and
oligofructose do not appear to have any considerable effect on
cholesterol and bile acid excretion in the small bowel. Finally, one of
the physiologic effects of inulin and oligofructose is to supply
substrate for fermentation in the colon.
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FOOTNOTES |
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REFERENCES |
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TOPABSTRACTINTRODUCTIONInulin and oligofructoseOther dietary fiber studies...CONCLUSIONREFERENCES |
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1. Andersson H. The ileostomy model for the study of carbohydrate digestion and carbohydrate effects on sterol excretion in man. Eur. J. Clin. Nutr. 1992;46:S69-S76
2. Andersson H., Bosaeus I. Sterol balance studies in man. A critical review. Eur J Clin. Nutr. 1993;47:153-159[Medline]
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4.
Bosaeus I., Andersson H. Short-term effect of two cholesterol-lowering diets on sterol excretion in ileostomy patients. Am. J. Clin. Nutr. 1987;45:54-59
5. Bosaeus I., Belfrage L., Lindgren C., Andersson H. Olive oil instead of butter increases net cholesterol excretion from the small bowel. Eur. J. Clin. Nutr. 1992;46:111-115[Medline]
6. Bosaeus I., Carlsson N.-G., Sandberg A.-S., Andersson H. Effect of wheat bran and pectin on bile acid and cholesterol excretion in ileostomy patients. Hum. Nutr. Clin. Nutr. 1986;40C:429-440[Medline]
7. Cummings J. H., Englyst H. N. Measurement of starch fermentation in the human large intestine. Can. J. Physiol. Pharmacol. 1991;69:121-129[Medline]
8. Ellegård L., Andersson H., Bosaeus I. Inulin and oligofructose do not influence the absorption of cholesterol, or the excretion of cholesterol, Ca, Mg, Zn, Fe, or bile acids but increase energy excretion in ileostomy subjects. Eur. J. Clin. Nutr. 1997;51:1-5[Medline]
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Englyst H. N., Cummings J. H. Digestion of polysaccharides of potato in the small intestine of man. Am. J. Clin. Nutr. 1987;45:423-431
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Englyst H. N., Cummings J. H. Digestion of the carbohydrates of banana (Musa paradisiaca sapientum) in the human small intestine. Am. J. Clin. Nutr. 1986;44:42-50
13. Finegold S. M., Sutter V. L., Boyle J. D., Shimada K. The normal flora of ileostomy and transverse colostomy effluents. J. Infect. Dis. 1970;122:376-381[Medline]
14. Holgate A. M., Read N. W. Relationship between small bowel transit time and absorption of a solid meal; influence of metoclopramide, magnesium sulfate and lactulose. Dig. Dis. Sci. 1983;28:812-819[Medline]
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Lia Å., Hallmans G., Sandberg B., Åhman P., Andersson H. Oat (ß-glucan) increases bile acid excretion and a fiber-rich barley fraction increases cholesterol excretion in ileostomy subjects. Am. J. Clin. Nutr. 1995;62:1245-1251
17. Malagelada J. R., Robertson J. S., Brown M. L., Remington M., Duenes J. A., Thomforde G. M., Carryer P. W. Intestinal transit of solid and liquid components of a meal in health. Gastroenterology 1984;87:1255-1263[Medline]
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19. Schweizer T. H., Andersson H., Langkilde A. M., Reimann S., Torsdottir I. Nutrients excreted in ileostomy effluents after consumption of mixed diets with beans or potatoes. II. Starch, dietary fibre and sugars. Eur. J. Clin. Nutr. 1990;44:567-575[Medline]
20. Soper N. J., Chapman N. J., Kelly K. A., Brown M. L., Phillips S. F., Vay Liang W.G.O. The "ileal brake" after ileal pouch-anal anastomosis. Gastroenterology 1990;98:111-116[Medline]
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23.
Zhang J.-X., Hallmans G., Andersson H., Bosaeus I., Åman P., Tidehag P., Stenling R., Lundén E., Dahlgren S. Effects of oat bran on plasma cholesterol and bile acid excretion in nine subjects with ileostomies. Am. J. Clin. Nutr. 1992;56:99-105
24. Zhang J.-X., Lundin E., Andersson H., Bosaeus I., Dahlgren S., Hallmans G., Stenling R., Åman P. Brewers' spent grain, serum lipids and fecal sterol excretion in human subject with ileostomies. J. Nutr. 1991;121:778-784
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