The effect of age, sex and level of intake of dietary fibre from wheat on large-bowel function in thirty healthy subjects

Stephen, Alison M.; Wiggins, H. S.; Englyst, Hans N.; Cole, Timothy J.; Wayman, B. J.

doi:10.1079/bjn19860116

Cited by 143 publications

(83 citation statements)

References 28 publications

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“…Biological mechanisms related to an age effect from physical activity on colon cancer risk have been proposed to act through improvements of the immune system among physically active elderly subjects (Shepard and Shek, 1995) or that physical activity, acting over a longer period of time in older people, is particularly important (Lee et al, 1991). In spite of no significant gender differences from physical activity on colon cancer risk observed in the present study, previous studies suggest sex differences as men and women show differences under controlled experimental conditions in gastrointestinal transit time, stool bulk and bile acid production (Stephen et al, 1986;Lampe et al, 1993).…”

Section: Resultscontrasting

confidence: 45%

Physical activity and risk of colorectal cancer in men and women

1996

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Summary We examined the association between self-reported occupational and recreational physical activity and the subsequent risk of colorectal cancer in a population-based cohort in Norway. During a mean follow-up time of 16.3 years for males and 15.5 years for females, 236 and 99 colon cancers and 170 and 58 rectal cancers were observed in males and females, respectively, among 53 242 males and 28 274 females who attended the screening between 1972 and 1978. Physical activity at a level equivalent to walking or bicycling for at least four hours a week during leisure-time was associated with decreased risk of colon cancer among females when compared with the sedentary group (RR=0.62, 95% CI 0.40-0.97). Reduced risk of colon cancer was particularly marked in the proximal colon (RR=0.51, 95% CI 0.28-0.93). This effect was not observed for occupational physical activity alone, probably due to a narrow range of self-reported physical activity at work among females. However, by combining occupational and recreational physical activity we observed an inverse dose-response effect as increasing total activity significantly reduced colon cancer risk (P for trend=0.04). Among males 45 years or older at entry to the study, an inverse dose-response effect was observed between total physical activity and colon cancer risk (P for trend = 0.04). We also found in males a stronger preventive effect for physical activity in the proximal as compared to distal colon. In addition, we found a borderline significant decrease in colon cancer risk for occupational physical activity in males 45 years or older when compared to the sedentary group (RR = 0.74, 95% CI 0.53-1.04). All results were adjusted for age, body mass index, serum cholesterol and geographic region. No association between physical activity and rectal cancer was observed in males or females. The protective effect of physical activity on colon cancer risk is discussed in regard to energy balance, dietary factors, age, social class, body mass index and gastrointestinal transit time.Keywords: physical activity; colorectal cancer; cohort study; gender differences; subsites Cancer of the large intestine is one of the most common neoplasms in western countries (Muir et al., 1987; Engeland et al., 1993). Recently, the role of exercise in the aetiology of colon carcinogenesis has drawn particular interest. A growing number of epidemiological studies have reported a protective effect of occupational physical activity on colon cancer risk (Garabrant et al., 1984;Gerhardsson et al., 1986;Brownson et al., 1989;Peters et al., 1989;Arbman et al., 1993; Chow et al., 1993;Fraser and Pearce, 1993). Others have observed that recreational physical activity protects against colon cancer (Wu et al., 1987;Slattery et al., 1988;Gerhardsson et al., 1988;Severson et al., 1989;Ballard-Barbash et al., 1990;Lee et al., 1991;Markowitz et al., 1992; Giovannuci et al., 1995). In contrast, the association between physical activity and risk of rectal cancer is more inconsistent (Vena et al., 1985;Ge...

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Section: Resultscontrasting

confidence: 45%

Physical activity and risk of colorectal cancer in men and women

1996

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“…Subjects with fast MTT (CH 4 7 ) had a lower pH and a higher fecal concentration of SCFAs than those with slow gut transit (CH 4 ). This con®rms that MTT is related to fecal pH (Stephen et al, 1986). Speeding up transit by pharmacological means also produced lower fecal pH, whereas SCFA concentrations rose.…”

Section: Discussionmentioning

confidence: 77%

Relationships between transit time in man and in vitro fermentation of dietary fiber by fecal bacteria

et al. 2000

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Objective: To assess the effects of drug-induced changes in mean transit time (MTT) on the activity of human fecal¯ora in vitro. Methods: The activity of fecal¯ora was estimated by the ability of a fecal inoculum to ferment a substrate (beet ®ber) in vitro in a batch system for 24 h. The inoculum was collected from 8 healthy volunteers studied during three 3-week randomized periods, who received a controlled diet alone (control period) or the same diet with either cisapride or loperamide. Cisapride and loperamide were adjusted in order to halve and double MTT measured during the control period. At the end of each period, the percentage disappearance of the initial added substrate and the concentration and the pro®le of short-chain fatty acids (SCFAs), were determined. Results: In the control period, the pH of the inoculum and SCFA concentration were inversely related to MTT (P 0.0001). Individual SCFA production was also signi®cantly related to MTT (P`0.01). Cisapride-reduced transit time was associated with a signi®cant rise in the concentrations of total SCFAs (P`0.05), propionic and butyric acids (P`0.05) and the percentage substrate disappearance (P`0.05). Inverse relations were observed during the loperamide period. Moreover, MTT was inversely related to the percentage substrate disappearance (P`0.001), SCFA production (P`0.001) and butyrate production (P`0.0005). Conclusion: Changes in MTT alter bacterial activity and modify the bacterial pathways affecting the proportion of individual SCFAs. Sponsorship:

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“…A female bias (p ϭ 0.012) for methanogenesis (63% females vs 37% males), which has been found in most studies (6,17,21,22,32), is unlikely to be a chance finding. The modeling, although distinguishing genetic and environmental effects within same sex subjects, cannot discriminate between genetic and behavioral effects that associate with the Y chromosome (or conversely with the X chromosome).…”

Section: Discussionmentioning

confidence: 91%

“…Male genetic or behavioral effects may influence mechanisms that control methanogenesis. For example, males have on average faster colonic transit (22,23) that would dilute methanogens, which are extremely slow growing anaerobes whose carriage is favored by slow transit. Also, sex differences in the enterohepatic circulation of bile acid (23,33,34) could influence carriage of methanogens because bile acid has been shown to inhibit methanogenesis (7,20).…”

Section: Discussionmentioning

confidence: 99%

“…Because the analytical methods used here required the data to be normally distributed, transformation of the data were required. Previous studies that analyzed breath methane have used a simple "excreters versus nonexcreters" scoring method for methane emission (17,21,(22)(23)(24)(25). Unfortunately, information may be lost in reducing data to a twopoint (dichotomous) scoring system.…”

Section: Human Experimentsmentioning

confidence: 99%

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Shared and unique environmental factors determine the ecology of methanogens in humans and rats

Florin

Zhu

Kirk

et al. 2000

The American Journal of Gastroenterology

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OBJECTIVE:This study ascertains the relative contributions of genetics and environment in determining methane emission in humans and rats. There is considerable interest in the factors determining the microbial species that inhabit the colon. Methanogens, which are archaebacteria, are an easily detected colonic luminal bacteria because they respire methane. They are present in some but not all human colons and lower animal hindguts. Opinion varies on the nature of the factors influencing this ecology with some studies proposing the existence of host genetic influences. METHODS:Methane emission was measured in human twin pairs by gas chromatography, and structural equation modeling was used to determine the proportion of genetic and environmental determinants. The importance of the timing of environmental effects and rat strain on the trait of methane emission were ascertained by experiments with cohabiting methanogenic and nonmethanogenic rats. RESULTS:Analysis of breath samples from 274 adolescent twin pairs and their families indicated that the major influences on the trait of methane emission are the result of shared (53%, 95% confidence interval 39 -61) and unique environmental (47%, 95% confidence interval 38 -56) effects. No significant autosomal genetic effects were detected, but as observed in other studies, men (37%) were less likely to excrete methane in their breath than women (63%). Investigation of methane emission in rats indicated that environmental effects in this animal are most potent during the weaning period, with stable gut microbial ecology thereafter for some but not all rat strains. CONCLUSIONS:These results are consistent with shared and unique environmental factors being the main determinants of the ecology of this colonic microbe. (Am J Gastroenterol 2000;95:2872-2879

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The effect of age, sex and level of intake of dietary fibre from wheat on large-bowel function in thirty healthy subjects

Cited by 143 publications

References 28 publications

Physical activity and risk of colorectal cancer in men and women

Physical activity and risk of colorectal cancer in men and women

Relationships between transit time in man and in vitro fermentation of dietary fiber by fecal bacteria

Shared and unique environmental factors determine the ecology of methanogens in humans and rats

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