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Effects of consumption of white bread and brown bread on the concentrations of fecal bile acids and neutral steroids and on fecal enzyme activities
Nutrition Research, Vol. 20, No. 3, pp. 327-333. 2000 Copyright 0 2000 Elsevier Science Inc. Printed in the USA. All rights rest~ved 0271.5317/OO/kee front matter ELSEVIER
PII:SO271-5317(00)00126-3
Effects of Consumption of White Bread and Brown Bread on the Concentrations of Fecal Bile acids and Neutral Steroids and on Fecal Enzyme Activities. *T. S. Srikumar Ph.D Department of Biochemistry, Faculty of Medicine, Kuwait University, P. 0. Box 24 923, 13 110 Safat, Kuwait
ABSTRACT The effects of consumption of white bread (low fiber) and brown bread (high fiber) on the fecal excretions of bile acids and neutral steroids and on fecal enzyme activities were assessed in ten healthy males (mean age 27 years). The study subjects included in their normal diet for one-week period in turn, white bread and brown bread (230 - 320 g/d). Fecal samples were collected at the two final consecutive days of each study week period. The daily fecal output was significantly higher, the concentration of cholic acid in feces significantly decreased by approx. 29% and a tendency for lower concentrations of other bile acids and neutral steroids occurred during consumption of brown bread compared to those during consumption of white bread. Also, the fecal enzyme activities of l3-glucosidase and B-glucuronidase significantly decreased during the same period, while those of urease and tryptophanase remained unchanged. The lower concentration of cholic acid and decreased enzyme activities of l3-glucosidase and l3-glucuronidase are indications of positive effects of consumption of brown bread. 0 2000 Elsewa
Sasnce
Inc.
Key words: White bread, Brown bread, Bile acids, Neutral steroids, Enzyme activities. INTRODUCTION The implication of fecal excretion of bile acids and neutral steroids and fecal enzyme activities as.risk factors for colon cancer is largely known [ 1, 2, 3,4]. The influence of diet on the changes in the fecal profile of these parameters has been extensively studied [5, 6,7,8]. It has been indicated that the main components of the diet involved in promoting/causing colorectal cancer risk are fat and animal protein [7], while dietary fiber was suggested to exert a protective effect [8, 91. The effect of consumption of different types of fiber on the concentration of bile acids, neutral steroids and fecal enzyme activities have been investigated in several studies both in rats and in humans: varying effects have been found [ 10, 111. It have been found that the type of bread significantly altered the fecal concentrations of cocarcinogenic lithocholic and deoxycholic acids in humans [12]. A study on Finnish subjects reported that those consuming a diet rich in fiber and dairy products had lower bacterial glucuronidase activity than those living in New York [4]. However, prospective data on the effects of consumption of different types of bread on the concentrations of compounds which are responsible for the production of carcinogens and toxicants in the gut are still lacking. *Corresponding
author 327
T.S. SHIKUMAR
328
The present study is designed to investigate the effects of consumption of white bread (low fiber) and brown bread (high fiber) on the changes in the fecal concentrations of bile acids and neutral steroids and on the fecal enzyme activities of healthy subjects. SUBJECTS AND METHODS Ten apparently healthy males between 26 and 38 years of age, and having body weight ranging from 63 to 86 kg participated in the study. During the two weeks of experimental period they ate a self-selected diet, but completed a food frequency questionnaire in the middle of each experimental week period and provided informations on their life style and health-related factors. The study subjects included in their normal diet for one-week period in turn, white bread (low fiber) and brown bread (high fiber), both approx. 230 - 320 g/day. During the experimental period, consumption of no other types of bread was allowed. Sample collection and Handling Twenty-four-hour morning feces were collected at the two final consecutive days of each experimental week period using deep-freeze toilets. Fecal samples were weighed and pH was measured on the same day of collection using a pH electrode as described previously [5] and then homogenized with a commercial blender. Aliquots of samples were stored at -2OOCuntil further analysis. Approx. 25 g of the 48-h homogenized fecal sample was thawed at room temperature and equal amount of water added, again homogenized and lyophilized, stored at -2OuC and used for analysis of bile acids and neutral steroids. Chemicals and Reference Standards All reagents used for lipid extraction and analysis were of analytical grade. Bile acid standards and campesterol were purchased from Sigma (St. Louis, MO, USA), stigmasterin from Merck Darmstadt (Germany), cholesterol and coprostanol from Steraloids Inc. (Wilton, NH, USA). All reference standards were >95% pure. Analysis of Bile acids and Neutral Steroids The concentrations of bile acids (lithocholic, deoxycholic, chenodeoxycholic and cholic) and neutral steroids (Stigmasterine, cholesterol, campesterol, coprostanol and l3sitosterol) were analyzed using gas-liquid chromatography [ 131. Nor-deoxycholic acid was used as an internal standard (3.014 pmol/l) and it was added prior to the extraction procedure. The lipids were extracted from approx. 150 mg of the lyophilized fecal sample using a mixture of trichloromethane : methanol (2: 1). The butyl ester-acetate derivatives were prepared and the final dried extract which was taken up in 0.3 ml trichloromethane, and 1 pl of this was injected into the gas chromatograph. Assay offecal enzyme activities All procedures were performed at 4oC. Aliquot of 2 g of homogenized fecal sample was taken in liquid nitrogen and dismemberment was done in Teflon plots for 8 min. at an amplitude of 1 cm in a microdismemberator. Approximately 2 g of dismembermented samples were added to 10 ml of phosphate-buffered saline (PBS, pH 6) and mixed well for a min., and the enzyme extract was used for assaying the enzyme activities of Rglucuronidase, l3-glucosidase (14). For measuring tryptophanase activity, 1 ml of fecal
BREAD AND FECAL ENZYME ACTIVITIES
Table 1: Daily intake of energy and some nutrients during consumption (low fiber) and brown bread (high fiber).
329
of white bread
Table 2: Contents of some nutrients of white bread (low fiber) and brown bread (high fiber). Nutrients (per 100 g) Dietary fiber (g) Crude protein (g) Pat (g) Moisture (%) Carhohvdrates
CP)
White bread 3.2 11 6 31
Brown bread 4.9 13 5 34
46
49
Table 3. The effects of consumption of white bread (low fiber) and brown bread (high fiber) on the concentrations (mg/g dry feces) of bile acids and neutral steroids in feces of humans. r&SD, n=lO
ap = 0.038 suspension was taken in 1 ml of 0.05M PBS (pH 6.5) buffer and to this was added 2 ml of cold acetone, mixed well, centrifuged at 2000 g for 15 minute at 4OC and the supernatant was used for the assaying the activity at 540 nm. Urease activity was measured using a kit obtained from Boehringer Mannheim GmdH (Cat. no. 542946). All the enzyme activities were measured spectrophotometrically.
T.S. SHIKUMAR
330
Table 4. The effects of consumption of white bread (low fiber) and brown bread (high fiber) on human fecal enzyme activities. &SD, n= 10
bp = 0.041 and cp = 0.029 Statistical Analysis Results are presented as means(SD). Student’s t-test for paired samples were used to determine statistical significance. Difference were considered significant when P values were CO.05. RESULTS Nutrient intake, fecal output and fecal pH The daily intake of some nutriets (computed from the-questionnaire) during the experimental period are presented in Table 1. There was a tendency for an increased daily intake of fiber, while the intake of all other nutrients more or less remained unchanged. The daily fecal output (219 g and 308 g while subjects subjects consumed white bread and brown bread, respectively) was significantly higher for subjects brown bread. Fecal pH tended to be lower for subjects consuming brown consuming bread (pH 5.71) than for subjects consuming white bread (pH 6.39). The content of some nutrients in both white bread and brown bread were more or less similar, except the fiber content was higher in brown bread (Table 2). Effects of consumption of white bread and brown bread on the concentrations acids and neutral steroids in feces.
of bile
The results presented are the means of values obtained from the analysis of stool specimens collected on two consecutive days (Table 3). The concentration of cholic acid significantly decreased by approximately 35% (~~0.05) during the consumption of brown bread and there was a tendency for a decrease in the concentrations of most of the bile acids and neutral steroids during the same period. Effects of consumption of white bread and brown bread on the fecal enzyme activities. The results of fecal enzyme activities are presented in Table 4. The enzyme activities of B-glucuronidase and R-glucosidase decreased significantly by 45% (p
BREAD AND FECAL ENZYME ACTIVITIES
DISCUSSION The concentration of bile acids and neutral steroids per gram of dry feces found in the present study were with in the range reported in the literature [2,4, 51. Fecal bile acid profiles have been compared between patients and healthy subjects and also between different populations having different types of dietary habits, but few studies have examined the same after consumption of different types of bread. Because of the limited number of study subjects and a relatively short experimental period, the significance of the present findings will not be discussed in detail. The lower concentration of cholic acid in feces after consumption of brown bread (high fiber) found in the present study was in accordance with other similar previous findings where whole grain rye bread (high fiber) reduced the concentration of this bile acid in feces [ 121. In one study on 8 healthy men, a large increase in the concentration of chenodeoxycholic and cholic acids, with a reciprocal decrease in those of lithocholic and deoxycholic acids occurred after a high fiber compared to a low fiber (neutral detergent fiber) and control diet [ 151. It was also reported that the fecal excretion of secondary bile acids decreased after consumption of 11 g of supplemental fiber per day in the form of whole grain bread for four weeks by 15 healthy men and women [ 161. Studies on populations such as those of Kupio (Finland) indicated that high dietary fiber intake, inspite of high dietary fat intake, increased the fecal volume and thereby a dilution effect of bile salts and other carcinogenic substances [17]. This might be true in the present study because the decreased excretion of cholic acid was associated with a larger fecal output. However, the significantly decreased concentration of cholic acid and a tendency for lowered concentrations of other bile acids in the feces after consumption of brown bread found in the present study may be regarded as positive effects. The significantly decreased enzyme activities of &glucuronidase and R-glucosidase was an indication of positive effects of consumption brown bread (high fiber). It has been reported that lower fecal enzyme activities of these compounds could reduce the risk of developing colon cancer (6). In several studies (8,18), the fecal l3-glucuronidase activity of subjects having vegetarian type of diets (high fiber) was found to be lower than those having mixed type of diets (low fiber). The effects of consumption of different types of bread on fecal enzyme activities are seldom studied, but various experiments have been performed both in humans and rats to investigate the effects of different types of fiber on this parameter and the results were often found to be inconsistent. For example, fecal B-glucuronidase activity increased in rats fed on pectin fiber diet, and decreased in those fed on cellulose and hemicellulose fiber diets (19). Rats fed on high cellulose (15%) diet markedly decreased their l3-glucosidase activity compared to those fed on regular cellulose (5%) diet (20). It has also been reported that fiber from wheat bran and carrot increased the B-glucosidase activity having no effect on &glucuronidase activity (21). In summary, findings in several studies more or less confirm that specific single fibers have differential effects on different fecal enzyme activities. CONCLUSION Consumption of brown bread instead of white bread could necessarily decrease the fecal excretions of some pro-carcinogenic compounds such as those of cholic acid and reduce the fecal enzyme activities of l3-glucuronidase and B-glucosidase. This might be due to the increased volume of fecal output or higher intake of fiber after consumption of brown bread.
331
T.S. SHIKUMAR
332
REFERENCES 1.
Owen RW, Dodo M, Thompson MH & Hill MJ. Fecal steroids and colorectal cancer. Nutr Cancer 1987;9: 73-80.
2.
Reddy BS & Wynder E. Metabolic epidemiology of colorectal cancer: fecal bile acids and neutral steroids in colon cancer patients with adenomatous polyps. Cancer 1977;39: 2533-2539.
3.
Williams RT. Toxicological implications of biotransformation flora. Toxicol. Appl. Pharmacol. 1972;23: 769-78 1.
4.
Reddy BS, & Wynder EL. Large-bowel carcinogensis: Fecal constituents of populations with diverse incidence rates of cancer. J Nat1 Cancer Inst 1972;50: 1437-42.
5.
van Faassen A, Bol J, van Dokkum W, Pikar NA, Ockhuizen T & Hermus RJJ. Bile acids, neutral steroids, and bacteria in feces as affected by a mixed, lactovegetarian and a vegan diet. Am J Clin Nutr 1987;46: 962-967.
6.
van Faassen A, hazen MJ, van den Brandt, van den Bogaard, Hermus RJJ & Janknegt RA. Bile acids and pH values in total feces and fecal water from habitually omnivorous and vegetarian subjects. Am J Clin Nutr 1993;58: 917922.
7.
Ling WH & Hanninen 0. Shifting from a conventional diet to an uncooked vegan diet reversibly alters fecal hydrolytic activities in humans. J Nutr 1992;122: 924930.
8.
Johansson GK, Ottowa L, Gustafsson JA. Shift from a mixed to a lactovegetarian diet: influence on some cancer-associated intestinal bacterial enzyme activities. Nutr Cancer 1990;14:239-46.
9.
Burkett DP, Walker ARP & painter NS. Dietary fiber and disease. 1974;229: 1068-1074.
10.
Spiller GA, Chernoff MC, Hill RA, Gates JE, Nassar JJ & Shipley EA. (1980). Effect of purified cellulose, pectin and a low-residue diet on fecal volatile fatty acids, transit time, and fecal weight in humans. Am J Clin Nutr 1980;33:754-759.
11.
Bianchini F, Caderni G, Dolara P, Fantetti L, Kriebel D. Effect of dietary fat, starch and cellulose on fecal bile acids in mice. J Nutr 1989;119: 1617-1624.
12.
Korpela JT, Korpela R & Aldercreutz H. Fecal bile acid metabolic pattern after administration of different types of bread. Gastroenterology 1992; 103: 12461253.
13.
Srikumar TS, Wezendonk b & van Dokkum W. Analysis of fecal bile acids and neutral steroids using gas-liquid chromatography. Ann Nutr Metab 1998;42:23136.
14.
Goldin BR, Swenson L, Johanna D, Sexton M & Gorbach SL. Effect of diet and lactobacillus acidophilus supplements on fecal bacterial enzymes. J Nat Cancer Inst 1980;64:255-261.
by intestinal micro
JAWA
333
BREAD AND FECAL ENZYME ACTIVITIES
15.
Ullrich IH, Lai HY, Vona L, Reid RL & Albrink MJ. Alterations in fecal steroid composition induced by changes in dietary fiber consumption. Am J Clin Nutr 198 1~34: 2054-2060.
16.
Reddy BS, Sharma C, Simi B, et al. Metabolic epidemiology of colon cancer: effect of dietary fiber on fecal mutagens and bile acids in healthy subjects. Cancer Res 1987;47:644-648.
17.
Reddy BS, Hedges A, Laakso K, Wynder EL. Fecal constituents of a high-risk North American and a low-risk Finnish population for the development of large bowel cancer. Cancer Lett 1978;4:217-222.
18.
Reddy BS, Weisburger JH & Wynder control by diet. Science 1973:416-17.
19.
Freeman HJ. Effects of differing purified cellulose, pectin, and hemicellulose fibre diets on fecal enzymes in 1, 2-dimethylhydrazine-induced rat colon carcinogenesis. Cancer Res 1986:46;5529-32.
20.
Prinzont R. Influence of high dietary cellulose on fecal glycosidases expermental rat colon carcinogenesis. Cancer Res 1984:44;557-61.
21.
Bauer HG, Asp N-G, Dahlqvist A, Fredlund PE, Nyman M & Oste R. Effect of two kinds of pectin and guar gum on 1,2_dimethylhydrazine initiation of colon tumors on fecal O-glucuronidase activity. Cancer Res 1981;41:2518-23. Accepted
for
publication
August
EL. Fecal bacterial
3, 1999.
R-glucuronidase:
in
PII:SO271-5317(00)00126-3
Effects of Consumption of White Bread and Brown Bread on the Concentrations of Fecal Bile acids and Neutral Steroids and on Fecal Enzyme Activities. *T. S. Srikumar Ph.D Department of Biochemistry, Faculty of Medicine, Kuwait University, P. 0. Box 24 923, 13 110 Safat, Kuwait
ABSTRACT The effects of consumption of white bread (low fiber) and brown bread (high fiber) on the fecal excretions of bile acids and neutral steroids and on fecal enzyme activities were assessed in ten healthy males (mean age 27 years). The study subjects included in their normal diet for one-week period in turn, white bread and brown bread (230 - 320 g/d). Fecal samples were collected at the two final consecutive days of each study week period. The daily fecal output was significantly higher, the concentration of cholic acid in feces significantly decreased by approx. 29% and a tendency for lower concentrations of other bile acids and neutral steroids occurred during consumption of brown bread compared to those during consumption of white bread. Also, the fecal enzyme activities of l3-glucosidase and B-glucuronidase significantly decreased during the same period, while those of urease and tryptophanase remained unchanged. The lower concentration of cholic acid and decreased enzyme activities of l3-glucosidase and l3-glucuronidase are indications of positive effects of consumption of brown bread. 0 2000 Elsewa
Sasnce
Inc.
Key words: White bread, Brown bread, Bile acids, Neutral steroids, Enzyme activities. INTRODUCTION The implication of fecal excretion of bile acids and neutral steroids and fecal enzyme activities as.risk factors for colon cancer is largely known [ 1, 2, 3,4]. The influence of diet on the changes in the fecal profile of these parameters has been extensively studied [5, 6,7,8]. It has been indicated that the main components of the diet involved in promoting/causing colorectal cancer risk are fat and animal protein [7], while dietary fiber was suggested to exert a protective effect [8, 91. The effect of consumption of different types of fiber on the concentration of bile acids, neutral steroids and fecal enzyme activities have been investigated in several studies both in rats and in humans: varying effects have been found [ 10, 111. It have been found that the type of bread significantly altered the fecal concentrations of cocarcinogenic lithocholic and deoxycholic acids in humans [12]. A study on Finnish subjects reported that those consuming a diet rich in fiber and dairy products had lower bacterial glucuronidase activity than those living in New York [4]. However, prospective data on the effects of consumption of different types of bread on the concentrations of compounds which are responsible for the production of carcinogens and toxicants in the gut are still lacking. *Corresponding
author 327
T.S. SHIKUMAR
328
The present study is designed to investigate the effects of consumption of white bread (low fiber) and brown bread (high fiber) on the changes in the fecal concentrations of bile acids and neutral steroids and on the fecal enzyme activities of healthy subjects. SUBJECTS AND METHODS Ten apparently healthy males between 26 and 38 years of age, and having body weight ranging from 63 to 86 kg participated in the study. During the two weeks of experimental period they ate a self-selected diet, but completed a food frequency questionnaire in the middle of each experimental week period and provided informations on their life style and health-related factors. The study subjects included in their normal diet for one-week period in turn, white bread (low fiber) and brown bread (high fiber), both approx. 230 - 320 g/day. During the experimental period, consumption of no other types of bread was allowed. Sample collection and Handling Twenty-four-hour morning feces were collected at the two final consecutive days of each experimental week period using deep-freeze toilets. Fecal samples were weighed and pH was measured on the same day of collection using a pH electrode as described previously [5] and then homogenized with a commercial blender. Aliquots of samples were stored at -2OOCuntil further analysis. Approx. 25 g of the 48-h homogenized fecal sample was thawed at room temperature and equal amount of water added, again homogenized and lyophilized, stored at -2OuC and used for analysis of bile acids and neutral steroids. Chemicals and Reference Standards All reagents used for lipid extraction and analysis were of analytical grade. Bile acid standards and campesterol were purchased from Sigma (St. Louis, MO, USA), stigmasterin from Merck Darmstadt (Germany), cholesterol and coprostanol from Steraloids Inc. (Wilton, NH, USA). All reference standards were >95% pure. Analysis of Bile acids and Neutral Steroids The concentrations of bile acids (lithocholic, deoxycholic, chenodeoxycholic and cholic) and neutral steroids (Stigmasterine, cholesterol, campesterol, coprostanol and l3sitosterol) were analyzed using gas-liquid chromatography [ 131. Nor-deoxycholic acid was used as an internal standard (3.014 pmol/l) and it was added prior to the extraction procedure. The lipids were extracted from approx. 150 mg of the lyophilized fecal sample using a mixture of trichloromethane : methanol (2: 1). The butyl ester-acetate derivatives were prepared and the final dried extract which was taken up in 0.3 ml trichloromethane, and 1 pl of this was injected into the gas chromatograph. Assay offecal enzyme activities All procedures were performed at 4oC. Aliquot of 2 g of homogenized fecal sample was taken in liquid nitrogen and dismemberment was done in Teflon plots for 8 min. at an amplitude of 1 cm in a microdismemberator. Approximately 2 g of dismembermented samples were added to 10 ml of phosphate-buffered saline (PBS, pH 6) and mixed well for a min., and the enzyme extract was used for assaying the enzyme activities of Rglucuronidase, l3-glucosidase (14). For measuring tryptophanase activity, 1 ml of fecal
BREAD AND FECAL ENZYME ACTIVITIES
Table 1: Daily intake of energy and some nutrients during consumption (low fiber) and brown bread (high fiber).
329
of white bread
Table 2: Contents of some nutrients of white bread (low fiber) and brown bread (high fiber). Nutrients (per 100 g) Dietary fiber (g) Crude protein (g) Pat (g) Moisture (%) Carhohvdrates
CP)
White bread 3.2 11 6 31
Brown bread 4.9 13 5 34
46
49
Table 3. The effects of consumption of white bread (low fiber) and brown bread (high fiber) on the concentrations (mg/g dry feces) of bile acids and neutral steroids in feces of humans. r&SD, n=lO
ap = 0.038 suspension was taken in 1 ml of 0.05M PBS (pH 6.5) buffer and to this was added 2 ml of cold acetone, mixed well, centrifuged at 2000 g for 15 minute at 4OC and the supernatant was used for the assaying the activity at 540 nm. Urease activity was measured using a kit obtained from Boehringer Mannheim GmdH (Cat. no. 542946). All the enzyme activities were measured spectrophotometrically.
T.S. SHIKUMAR
330
Table 4. The effects of consumption of white bread (low fiber) and brown bread (high fiber) on human fecal enzyme activities. &SD, n= 10
bp = 0.041 and cp = 0.029 Statistical Analysis Results are presented as means(SD). Student’s t-test for paired samples were used to determine statistical significance. Difference were considered significant when P values were CO.05. RESULTS Nutrient intake, fecal output and fecal pH The daily intake of some nutriets (computed from the-questionnaire) during the experimental period are presented in Table 1. There was a tendency for an increased daily intake of fiber, while the intake of all other nutrients more or less remained unchanged. The daily fecal output (219 g and 308 g while subjects subjects consumed white bread and brown bread, respectively) was significantly higher for subjects brown bread. Fecal pH tended to be lower for subjects consuming brown consuming bread (pH 5.71) than for subjects consuming white bread (pH 6.39). The content of some nutrients in both white bread and brown bread were more or less similar, except the fiber content was higher in brown bread (Table 2). Effects of consumption of white bread and brown bread on the concentrations acids and neutral steroids in feces.
of bile
The results presented are the means of values obtained from the analysis of stool specimens collected on two consecutive days (Table 3). The concentration of cholic acid significantly decreased by approximately 35% (~~0.05) during the consumption of brown bread and there was a tendency for a decrease in the concentrations of most of the bile acids and neutral steroids during the same period. Effects of consumption of white bread and brown bread on the fecal enzyme activities. The results of fecal enzyme activities are presented in Table 4. The enzyme activities of B-glucuronidase and R-glucosidase decreased significantly by 45% (p
BREAD AND FECAL ENZYME ACTIVITIES
DISCUSSION The concentration of bile acids and neutral steroids per gram of dry feces found in the present study were with in the range reported in the literature [2,4, 51. Fecal bile acid profiles have been compared between patients and healthy subjects and also between different populations having different types of dietary habits, but few studies have examined the same after consumption of different types of bread. Because of the limited number of study subjects and a relatively short experimental period, the significance of the present findings will not be discussed in detail. The lower concentration of cholic acid in feces after consumption of brown bread (high fiber) found in the present study was in accordance with other similar previous findings where whole grain rye bread (high fiber) reduced the concentration of this bile acid in feces [ 121. In one study on 8 healthy men, a large increase in the concentration of chenodeoxycholic and cholic acids, with a reciprocal decrease in those of lithocholic and deoxycholic acids occurred after a high fiber compared to a low fiber (neutral detergent fiber) and control diet [ 151. It was also reported that the fecal excretion of secondary bile acids decreased after consumption of 11 g of supplemental fiber per day in the form of whole grain bread for four weeks by 15 healthy men and women [ 161. Studies on populations such as those of Kupio (Finland) indicated that high dietary fiber intake, inspite of high dietary fat intake, increased the fecal volume and thereby a dilution effect of bile salts and other carcinogenic substances [17]. This might be true in the present study because the decreased excretion of cholic acid was associated with a larger fecal output. However, the significantly decreased concentration of cholic acid and a tendency for lowered concentrations of other bile acids in the feces after consumption of brown bread found in the present study may be regarded as positive effects. The significantly decreased enzyme activities of &glucuronidase and R-glucosidase was an indication of positive effects of consumption brown bread (high fiber). It has been reported that lower fecal enzyme activities of these compounds could reduce the risk of developing colon cancer (6). In several studies (8,18), the fecal l3-glucuronidase activity of subjects having vegetarian type of diets (high fiber) was found to be lower than those having mixed type of diets (low fiber). The effects of consumption of different types of bread on fecal enzyme activities are seldom studied, but various experiments have been performed both in humans and rats to investigate the effects of different types of fiber on this parameter and the results were often found to be inconsistent. For example, fecal B-glucuronidase activity increased in rats fed on pectin fiber diet, and decreased in those fed on cellulose and hemicellulose fiber diets (19). Rats fed on high cellulose (15%) diet markedly decreased their l3-glucosidase activity compared to those fed on regular cellulose (5%) diet (20). It has also been reported that fiber from wheat bran and carrot increased the B-glucosidase activity having no effect on &glucuronidase activity (21). In summary, findings in several studies more or less confirm that specific single fibers have differential effects on different fecal enzyme activities. CONCLUSION Consumption of brown bread instead of white bread could necessarily decrease the fecal excretions of some pro-carcinogenic compounds such as those of cholic acid and reduce the fecal enzyme activities of l3-glucuronidase and B-glucosidase. This might be due to the increased volume of fecal output or higher intake of fiber after consumption of brown bread.
331
T.S. SHIKUMAR
332
REFERENCES 1.
Owen RW, Dodo M, Thompson MH & Hill MJ. Fecal steroids and colorectal cancer. Nutr Cancer 1987;9: 73-80.
2.
Reddy BS & Wynder E. Metabolic epidemiology of colorectal cancer: fecal bile acids and neutral steroids in colon cancer patients with adenomatous polyps. Cancer 1977;39: 2533-2539.
3.
Williams RT. Toxicological implications of biotransformation flora. Toxicol. Appl. Pharmacol. 1972;23: 769-78 1.
4.
Reddy BS, & Wynder EL. Large-bowel carcinogensis: Fecal constituents of populations with diverse incidence rates of cancer. J Nat1 Cancer Inst 1972;50: 1437-42.
5.
van Faassen A, Bol J, van Dokkum W, Pikar NA, Ockhuizen T & Hermus RJJ. Bile acids, neutral steroids, and bacteria in feces as affected by a mixed, lactovegetarian and a vegan diet. Am J Clin Nutr 1987;46: 962-967.
6.
van Faassen A, hazen MJ, van den Brandt, van den Bogaard, Hermus RJJ & Janknegt RA. Bile acids and pH values in total feces and fecal water from habitually omnivorous and vegetarian subjects. Am J Clin Nutr 1993;58: 917922.
7.
Ling WH & Hanninen 0. Shifting from a conventional diet to an uncooked vegan diet reversibly alters fecal hydrolytic activities in humans. J Nutr 1992;122: 924930.
8.
Johansson GK, Ottowa L, Gustafsson JA. Shift from a mixed to a lactovegetarian diet: influence on some cancer-associated intestinal bacterial enzyme activities. Nutr Cancer 1990;14:239-46.
9.
Burkett DP, Walker ARP & painter NS. Dietary fiber and disease. 1974;229: 1068-1074.
10.
Spiller GA, Chernoff MC, Hill RA, Gates JE, Nassar JJ & Shipley EA. (1980). Effect of purified cellulose, pectin and a low-residue diet on fecal volatile fatty acids, transit time, and fecal weight in humans. Am J Clin Nutr 1980;33:754-759.
11.
Bianchini F, Caderni G, Dolara P, Fantetti L, Kriebel D. Effect of dietary fat, starch and cellulose on fecal bile acids in mice. J Nutr 1989;119: 1617-1624.
12.
Korpela JT, Korpela R & Aldercreutz H. Fecal bile acid metabolic pattern after administration of different types of bread. Gastroenterology 1992; 103: 12461253.
13.
Srikumar TS, Wezendonk b & van Dokkum W. Analysis of fecal bile acids and neutral steroids using gas-liquid chromatography. Ann Nutr Metab 1998;42:23136.
14.
Goldin BR, Swenson L, Johanna D, Sexton M & Gorbach SL. Effect of diet and lactobacillus acidophilus supplements on fecal bacterial enzymes. J Nat Cancer Inst 1980;64:255-261.
by intestinal micro
JAWA
333
BREAD AND FECAL ENZYME ACTIVITIES
15.
Ullrich IH, Lai HY, Vona L, Reid RL & Albrink MJ. Alterations in fecal steroid composition induced by changes in dietary fiber consumption. Am J Clin Nutr 198 1~34: 2054-2060.
16.
Reddy BS, Sharma C, Simi B, et al. Metabolic epidemiology of colon cancer: effect of dietary fiber on fecal mutagens and bile acids in healthy subjects. Cancer Res 1987;47:644-648.
17.
Reddy BS, Hedges A, Laakso K, Wynder EL. Fecal constituents of a high-risk North American and a low-risk Finnish population for the development of large bowel cancer. Cancer Lett 1978;4:217-222.
18.
Reddy BS, Weisburger JH & Wynder control by diet. Science 1973:416-17.
19.
Freeman HJ. Effects of differing purified cellulose, pectin, and hemicellulose fibre diets on fecal enzymes in 1, 2-dimethylhydrazine-induced rat colon carcinogenesis. Cancer Res 1986:46;5529-32.
20.
Prinzont R. Influence of high dietary cellulose on fecal glycosidases expermental rat colon carcinogenesis. Cancer Res 1984:44;557-61.
21.
Bauer HG, Asp N-G, Dahlqvist A, Fredlund PE, Nyman M & Oste R. Effect of two kinds of pectin and guar gum on 1,2_dimethylhydrazine initiation of colon tumors on fecal O-glucuronidase activity. Cancer Res 1981;41:2518-23. Accepted
for
publication
August
EL. Fecal bacterial
3, 1999.
R-glucuronidase:
in