Studies on people who drink diet sodas shows that "something" in diet sodas induces these people to gain weight (1).
The "something" is the artificial sweeteners that are in the diet drinks. These stimulate alpha-gustducin (2). This is a taste receptor that allows us to taste sweetness. It is in our intestine in addition to on our tongue.
In our intestine, once stimulated, it increases sugar absorption. Artificial sweeteners may stimulate it more than actual sugar or conversely may not increase the compensatory normal elevation in glucagon-like peptide-1 (not in the literature so just a guess by me). Meaning when we use artificial sweeteners we often end up absorbing more sugar and more calories. Result = a tendency to gain weight.
This same effect should happen whether the artificial sweetener is in diet drinks or anything else we consume. Acesulfame K (acesulfame potassium or K) and Splenda (sucralose) are particularly bad in this regard.
1. http://www.cbsnews.com/stories/2005/06/13/health/webmd/main701408.shtml Diet Soda Drinkers Gain Weight Overweight Risk Soars 41 Percent With Each Daily Can Of Diet Soda J
June 13, 2005 (WebMD)
People who drink diet soft drinks don't lose weight. In fact, they gain weight, a new study shows.
The findings come from eight years of data collected by Sharon P. Fowler...
For regular soft-drink drinkers, the risk of becoming overweight or obese was:
26 percent for up to 1/2 can each day
30.4 percent for 1/2 to one can each day
32.8 percent for 1 to 2 cans each day
47.2 percent for more than 2 cans each day.
For diet soft-drink drinkers, the risk of becoming overweight or obese was:
36.5 percent for up to 1/2 can each day
37.5 percent for 1/2 to one can each day
54.5 percent for 1 to 2 cans each day
57.1 percent for more than 2 cans each day.
...something linked to diet soda drinking is also linked to obesity. ...
2. J Physiol. 2007 Jul 1;582(Pt 1):379-92
Sweet taste receptors in rat small intestine stimulate glucose absorption through apical GLUT2.
Mace OJ...
Sweet taste receptors in rat small intestine stimulate glucose absorption through apical GLUT2. Natural sugars and artificial sweeteners are sensed by receptors in taste buds. ...
Intestinal brush cells or solitary chemosensory cells (SCCs) have a structure similar to lingual taste cells and strongly express alpha-gustducin. ...
Artificial sweeteners increase glucose absorption in the order acesulfame potassium approximately sucralose > saccharin...artificial sweeteners are nutritionally active, because they can signal to a functional taste reception system to increase sugar absorption during a meal...
PMID: 17495045
Nerissa
Tuesday, October 30, 2007
Friday, October 12, 2007
Lowering chocolate cravings
Intestinal bacteria influence our eating habits. For example, they can increase our desire for chocolate. We should be able to manipulate these bacteria to change our food desires and help us eat a healthier diet. In this post I hypothesize that eating more pectin, consuming chitosan and drinking tea will lower our craving for chocolate. Being a male helps too!
By seeing the relationship of taurine and glycine in chocolate cravers (taurine high in non-cravers and glycine high in cravers) and knowing that only these two amino acids conjugate with bile it is fairly easy to determine the bacteria that bile salts are involved.
PMID 7611405, below, points out the amazing fact that chocolate is a mimic for the taurine conjugated type of bile salt. PMID 17152920, also below, takes this information and indicates the bacteria that consume this type of bile salt. These bacteria, mostly of the bacteriodes type, should be the ones that induce a chocolate craving.
What to do? Simple - increase the bacteria that consume glycine conjugated bile. These will out-compete the ones that induce chocolate cravings. Consuming a high pectin diet will do this. Citrus fruit and in particular grapefruit is sky high in pectin.
Another thing that might help is to consume chitosan. This substance selectively inhibits bacteriodes bacteria. It is extracted from the shells of shrimp and other sea crustaceans.
Also, consider regular consumption of tea. PMID 16962743 indicates this lowers bacteroides.
Grapefruit, chitosan and tea are already commonly used in weight reduction programs. While they may not help any particular person drop excess body weight they should at least lower their chocolate craving which might be a start to a better diet.
Special note for the ladies and my male to female transsexual friends - PMID 12877349, below, indicates that estrogen increases taurine bile salt and furthermore that the bacterial activity on the bile salt is elevated. Can it be a surprise that estrogen increases chocolate craving? My experience in transitioning from male physiology to female physiology supports this idea.
http://news.yahoo.com/s/ap/20071012/ap_on_he_me/diet_chocolate_craving
Scientists explain chocolate cravings
By SETH BORENSTEIN, AP Science Writer
Fri Oct 12, 4:34 AM ET
WASHINGTON - If that craving for chocolate sometimes feels like it is coming from deep in your gut, that's because maybe it is.
A small study links the type of bacteria living in people's digestive system to a desire for chocolate. Everyone has a vast community of microbes in their guts. But people who crave daily chocolate show signs of having different colonies of bacteria than people who are immune to chocolate's allure.
That may be the case for other foods, too. The idea could eventually lead to treating some types of obesity by changing the composition of the trillions of bacteria occupying the intestines and stomach, said Sunil Kochhar, co-author of the study. It appears Friday in the peer-reviewed Journal of Proteome Research.
Kochhar is in charge of metabolism research at the Nestle Research Center in Lausanne, Switzerland. The food conglomerate Nestle SA paid for the study. But this isn't part of an effort to convert a few to the dark side (or even milk) side of cocoa, Kocchar said.
In fact, the study was delayed because it took a year for the researchers to find 11 men who don't eat chocolate.
Kochhar compared the blood and urine of those 11 men, who he jokingly called "weird" for their indifference to chocolate, to 11 similar men who ate chocolate daily. They were all healthy, not obese, and were fed the same food for five days.
The researchers examined the byproducts of metabolism in their blood and urine and found that a dozen substances were significantly different between the two groups. For example, the amino acid glycine was higher in chocolate lovers, while taurine (an active ingredient in energy drinks) was higher in people who didn't eat chocolate. Also chocolate lovers had lower levels of the bad cholesterol, LDL.
The levels of several of the specific substances that were different in the two groups are known to be linked to different types of bacteria, Kochhar said.
Still to be determined is if the bacteria cause the craving, or if early in life people's diets changed the bacteria, which then reinforced food choices.
How gut bacteria affect people is a hot field of scientific research.
Past studies have shown that intestinal bacteria change when people lose weight, said Dr. Sam Klein, an obesity expert and professor of medicine at Washington University in St. Louis.
Since bacteria interact with what you eat, it is logical to think that there is a connection between those microbes and desires for certain foods, said Klein, who wasn't part of Kochhar's study.
Kochhar's research makes so much sense that people should have thought of it earlier, said J. Bruce German, professor of food chemistry at the University of California Davis. While five outside scientists thought the study was intriguing, Dr. Richard Bergman at the University of Southern California School of Medicine, had concerns about the accuracy of the initial division of the men into groups that wanted chocolate or were indifferent to it.
What matters to Kochhar is where the research could lead.
Kochhar said the relationship between food, people and what grows in their gut is important for the future: "If we understand the relationship, then we can find ways to nudge it in the right direction."
Am J Physiol. 1995 Jun;268(6 Pt 1):G1051-9.
Role of amidation in bile acid effect on DNA synthesis by regenerating mouse liver.
Barbero ER, Herrera MC, Monte MJ, Serrano MA, Marin JJ.
Department of Physiology, Faculty of Pharmacy, University of Salamanca, Spain.
Effect of bile acids on DNA synthesis by the regenerating liver was investigated in mice in vivo after partial hepatectomy (PH). Radioactivity incorporation into DNA after [14C]thymidine intraperitoneal administration peaked at 48 h after PH. At this time a significant taurocholate-induced dose-dependent reduction in DNA synthesis without changes in total liver radioactivity content was found (half-maximal effect at approximately 0.1 mumol/g body wt). Effect of taurocholate (0.5 mumol/g body wt) was mimicked by chocolate, ursodeoxycholate, deoxycholate, dehydrocholate, tauroursodeoxycholate, taurochenodeoxycholate, and taurodeoxycholate. In contrast, chenodeoxycholate, glycocholate, glycochenodeoxycholate, glycoursodeoxycholate, glycodeoxycholate, 5 beta-cholestane, bromosulfophthalein, and free taurine lacked this effect. No relationship between hydrophobic-hydrophilic balance and inhibitory effect was observed. Analysis by high-performance liquid chromatography indicated that inhibition of thymidine incorporation into DNA was not accompanied by an accumulation of phosphorylated DNA precursors in the liver but rather by a parallel increase in nucleotide catabolism. Bile acid-induced modifications in DNA synthesis were observed in vivo even in the absence of changes in toxicity tests, which suggests that the inhibitory effect shared by most unconjugated and tauroconjugated bile acids but not by glycoconjugated bile acids should be accounted for by mechanisms other than nonselective liver cell injury.
PMID: 7611405
Lipids. 2006 Sep;41(9):835-43
Deoxycholic acid formation in gnotobiotic mice associated with human intestinal bacteria.
Narushima S, Itoha K, Miyamoto Y, Park SH, Nagata K, Kuruma K, Uchida K.
Laboratory of Veterinary Public Health, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan.
In humans and animals, intestinal flora is indispensable for bile acid transformation. The goal of our study was to establish gnotobiotic mice with intestinal bacteria of human origin in order to examine the role of intestinal bacteria in the transformation of bile acids in vivo using the technique of gnotobiology. Eight strains of bile acid-deconjugating bacteria were isolated from ex-germ-free mice inoculated with a human fecal dilution of 10(-6), and five strains of 7alpha-dehydroxylating bacteria were isolated from the intestine of limited human flora mice inoculated only with clostridia. The results of biochemical tests and 16S rDNA sequence analysis showed that seven out of eight bile acid-deconjugating strains belong to a bacteroides cluster (Bacteroides vulgatus, B. distasonis, and B. uniformis), and one strain had high similarity with Bilophila wadsworthia. All five strains that converted cholic acid to deoxycholic acid had greatest similarity with Clostridium hylemonae. A combination of 10 isolated strains converted taurocholic acid into deoxycholic acid both in vitro and in the mouse intestine. These results indicate that the predominant bacteria, mainly Bacteroides, in human feces comprise one of the main bacterial groups for the deconjugation of bile acids, and clostridia may play an important role in 7aplha-dehydroxylation of free-form primary bile acids in the intestine although these strains are not predominant. The gnotobiotic mouse with bacteria of human origin could be a useful model in studies of bile acid metabolism by human intestinal bacteria in vivo.
PMID: 17152920
http://www.ingentaconnect.com/content/cabi/bjn/1989/00000062/00000003/art00005;jsessionid=2e953w9ke2hvh.alice?
Bile acid conjugation and hepatic taurine concentration in rats fed on pectin
Authors: Ide, T.1; Horii, M.1; Kawashima, K.1; Yamamoto, T.1
Source: British Journal of Nutrition, Volume 62, Number 3, November 1989 , pp. 539-550(12)
Publisher: CABI Publishing
A relationship between bile acid conjugation and hepatic taurine concentration was investigated in rats fed on citrus pectin. When rats were fed on the diets containing varying amounts of pectin (10, 30, 60 and 100 g/kg dietary levels), biliary excretion of bile acids increased as the dietary levels of pectin increased. The increase was entirely due to the glycine-conjugated bile acids. The biliary excretion of taurine-conjugated bile acid was somewhat decreased as the dietary level of the fibre increased. Consequently, most of the bile acids were conjugated with glycine in rats fed on the diet containing 100 g pectin/kg. On the other hand, dietary cellulose (60 and 100 g/kg) did not affect the biliary bile acid excretions. The major proportion of bile acids in rats receiving a fibre-free diet and the diets containing cellulose were conjugated with taurine. Hepatic taurine concentrations decreased as the dietary levels of pectin, but not of cellulose, increased. Although dietary pectin (100 g/kg) also slightly decreased the taurine concentration in the kidney, those concentrations in other non-hepatic tissues examined (heart, brain and serum) were unaffected by the dietary fibre. Supplementation of the diet containing 100 g pectin/kg with methionine (10 g/kg) and taurine (10 and 50 g/kg) strikingly increased hepatic taurine concentrations. In this situation, the conjugation of bile acid with glycine was almost abolished and taurine conjugates became abundant in the bile of these animals. It is suggested that dietary pectin mediated an increase in the biliary bile acid excretion which may have depleted the hepatic pool of taurine available for bile acid conjugation and, thus, increased glycine conjugation of bile acids.
Keywords: Bile acid conjugation; Pectin; Taurine; Rat
Document Type: Research article
DOI: 10.1079/BJN19890056
Affiliations: 1: Laboratory of Nutrition Chemistry, National Food Research Institute, Ministry of Agriculture, Forestry and Fisheries, Tsukuba Science City, 305, Japan
Folia Microbiol (Praha). 2006;51(4):306-8
Effect of chitosan on the growth of human colonic bacteria.Simůnek J, Tishchenko G, Hodrová B, Bartonová H.Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Prague, Czechia. simunek@iapg.cas.cz
Growth of 6 bacterial strains representing dominant members of the human colonic microflora was measured in the presence of 0.025, 0.05 and 0.5 % chitosan (from shrimp shells, with a 97 % final degree of deacetylation). The effect of chitosan was variable and dependent on bacterial species. The most susceptible to chitosan were bacteria belonging to genera Bacteroides and Clostridium (91-97% growth inhibition). On the other hand, Roseburia sp., Eubacterium sp. and Faecalibacterium sp. were more resistant (63-83 % inhibition of growth). Chitosan can thus be considered as one of the means for influencing the bacterial population in the human colon.PMID: 17007432
Exp Toxicol Pathol. 2003 Jun;54(5-6):381-6Influence of ethinyloestradiol propanolsulphonate on serum bile acids in healthy volunteers.
Barth A, Klinger G, Rost M.Institute of Pharmacology and Toxicology, Friedrich Schiller University Jena, Germany. Astrid.Barth@mti-n.uni-jena.de
The present work was done to clarify the relevance of altered serum bile acid (BA) profile in healthy women after the administration of the depot oestrogen ethinyloestradiol propanolsulphonate (EES). In the serum of 20 healthy women before and two times after oral EES application, 11 free and 14 taurine- and glycine-conjugated BA were analysed by HPLC with postcolumn derivatisation and fluorescence detection. EES significantly enhanced the total serum BA concentration and that of taurine-conjugated BAs, more pronounced the secondary BAs taurodeoxycholic, tauroursodeoxycholic and taurolithocholic acid. These secondary BAs are produced in the intestine by bacteria due to 7alpha-dehydroxylation of the primary BAs cholic and chenodeoxycholic acid. Because of unchanged free BAs, also produced by intestinal bacteria due to deconjugation, the results were interpreted as a sign of disturbed transport of BAs into the liver. Inhibition of the liver Na(+)-bile salt co-transporter (Ntcp) in the sinusoidal membrane by ethinyloestradiol, formed from the prodrug EES, may be responsible for the altered BA profile in serum.
PMID: 12877349
Res Microbiol. 2006 Nov;157(9):876-84
Effect of tea phenolics and their aromatic fecal bacterial metabolites on intestinal microbiota.
Lee HC, Jenner AM, Low CS, Lee YK.Department of Microbiology, National University of Singapore, 5 Science Drive 2, Singapore 117597, Republic of Singapore.
Tea is rich in polyphenols and other phenolics that have been widely reported to have beneficial health effects. However, dietary polyphenols are not completely absorbed from the gastrointestinal tract and are metabolized by the gut microflora so that they and their metabolites may accumulate to exert physiological effects. In this study, we investigated the influence of the phenolic components of a tea extract and their aromatic metabolites upon bacterial growth. Fecal homogenates containing bacteria significantly catalyzed tea phenolics, including epicatechin, catechin, 3-O-methyl gallic acid, gallic acid and caffeic acid to generate aromatic metabolites dependent on bacterial species. Different strains of intestinal bacteria had varying degrees of growth sensitivity to tea phenolics and metabolites. Growth of certain pathogenic bacteria such as Clostridium perfringens, Clostridium difficile and Bacteroides spp. was significantly repressed by tea phenolics and their derivatives, while commensal anaerobes like Clostridium spp., Bifidobacterium spp. and probiotics such as Lactobacillus sp. were less severely affected. This indicates that tea phenolics exert significant effects on the intestinal environment by modulation of the intestinal bacterial population, probably by acting as metabolic prebiotics. Our observations provide further evidence for the importance of colonic bacteria in the metabolism, absorption and potential activity of phenolics in human health and disease. The bioactivity of different phenolics may play an important role in the maintenance of gastrointestinal health.
PMID: 16962743
Nerissa
By seeing the relationship of taurine and glycine in chocolate cravers (taurine high in non-cravers and glycine high in cravers) and knowing that only these two amino acids conjugate with bile it is fairly easy to determine the bacteria that bile salts are involved.
PMID 7611405, below, points out the amazing fact that chocolate is a mimic for the taurine conjugated type of bile salt. PMID 17152920, also below, takes this information and indicates the bacteria that consume this type of bile salt. These bacteria, mostly of the bacteriodes type, should be the ones that induce a chocolate craving.
What to do? Simple - increase the bacteria that consume glycine conjugated bile. These will out-compete the ones that induce chocolate cravings. Consuming a high pectin diet will do this. Citrus fruit and in particular grapefruit is sky high in pectin.
Another thing that might help is to consume chitosan. This substance selectively inhibits bacteriodes bacteria. It is extracted from the shells of shrimp and other sea crustaceans.
Also, consider regular consumption of tea. PMID 16962743 indicates this lowers bacteroides.
Grapefruit, chitosan and tea are already commonly used in weight reduction programs. While they may not help any particular person drop excess body weight they should at least lower their chocolate craving which might be a start to a better diet.
Special note for the ladies and my male to female transsexual friends - PMID 12877349, below, indicates that estrogen increases taurine bile salt and furthermore that the bacterial activity on the bile salt is elevated. Can it be a surprise that estrogen increases chocolate craving? My experience in transitioning from male physiology to female physiology supports this idea.
http://news.yahoo.com/s/ap/20071012/ap_on_he_me/diet_chocolate_craving
Scientists explain chocolate cravings
By SETH BORENSTEIN, AP Science Writer
Fri Oct 12, 4:34 AM ET
WASHINGTON - If that craving for chocolate sometimes feels like it is coming from deep in your gut, that's because maybe it is.
A small study links the type of bacteria living in people's digestive system to a desire for chocolate. Everyone has a vast community of microbes in their guts. But people who crave daily chocolate show signs of having different colonies of bacteria than people who are immune to chocolate's allure.
That may be the case for other foods, too. The idea could eventually lead to treating some types of obesity by changing the composition of the trillions of bacteria occupying the intestines and stomach, said Sunil Kochhar, co-author of the study. It appears Friday in the peer-reviewed Journal of Proteome Research.
Kochhar is in charge of metabolism research at the Nestle Research Center in Lausanne, Switzerland. The food conglomerate Nestle SA paid for the study. But this isn't part of an effort to convert a few to the dark side (or even milk) side of cocoa, Kocchar said.
In fact, the study was delayed because it took a year for the researchers to find 11 men who don't eat chocolate.
Kochhar compared the blood and urine of those 11 men, who he jokingly called "weird" for their indifference to chocolate, to 11 similar men who ate chocolate daily. They were all healthy, not obese, and were fed the same food for five days.
The researchers examined the byproducts of metabolism in their blood and urine and found that a dozen substances were significantly different between the two groups. For example, the amino acid glycine was higher in chocolate lovers, while taurine (an active ingredient in energy drinks) was higher in people who didn't eat chocolate. Also chocolate lovers had lower levels of the bad cholesterol, LDL.
The levels of several of the specific substances that were different in the two groups are known to be linked to different types of bacteria, Kochhar said.
Still to be determined is if the bacteria cause the craving, or if early in life people's diets changed the bacteria, which then reinforced food choices.
How gut bacteria affect people is a hot field of scientific research.
Past studies have shown that intestinal bacteria change when people lose weight, said Dr. Sam Klein, an obesity expert and professor of medicine at Washington University in St. Louis.
Since bacteria interact with what you eat, it is logical to think that there is a connection between those microbes and desires for certain foods, said Klein, who wasn't part of Kochhar's study.
Kochhar's research makes so much sense that people should have thought of it earlier, said J. Bruce German, professor of food chemistry at the University of California Davis. While five outside scientists thought the study was intriguing, Dr. Richard Bergman at the University of Southern California School of Medicine, had concerns about the accuracy of the initial division of the men into groups that wanted chocolate or were indifferent to it.
What matters to Kochhar is where the research could lead.
Kochhar said the relationship between food, people and what grows in their gut is important for the future: "If we understand the relationship, then we can find ways to nudge it in the right direction."
Am J Physiol. 1995 Jun;268(6 Pt 1):G1051-9.
Role of amidation in bile acid effect on DNA synthesis by regenerating mouse liver.
Barbero ER, Herrera MC, Monte MJ, Serrano MA, Marin JJ.
Department of Physiology, Faculty of Pharmacy, University of Salamanca, Spain.
Effect of bile acids on DNA synthesis by the regenerating liver was investigated in mice in vivo after partial hepatectomy (PH). Radioactivity incorporation into DNA after [14C]thymidine intraperitoneal administration peaked at 48 h after PH. At this time a significant taurocholate-induced dose-dependent reduction in DNA synthesis without changes in total liver radioactivity content was found (half-maximal effect at approximately 0.1 mumol/g body wt). Effect of taurocholate (0.5 mumol/g body wt) was mimicked by chocolate, ursodeoxycholate, deoxycholate, dehydrocholate, tauroursodeoxycholate, taurochenodeoxycholate, and taurodeoxycholate. In contrast, chenodeoxycholate, glycocholate, glycochenodeoxycholate, glycoursodeoxycholate, glycodeoxycholate, 5 beta-cholestane, bromosulfophthalein, and free taurine lacked this effect. No relationship between hydrophobic-hydrophilic balance and inhibitory effect was observed. Analysis by high-performance liquid chromatography indicated that inhibition of thymidine incorporation into DNA was not accompanied by an accumulation of phosphorylated DNA precursors in the liver but rather by a parallel increase in nucleotide catabolism. Bile acid-induced modifications in DNA synthesis were observed in vivo even in the absence of changes in toxicity tests, which suggests that the inhibitory effect shared by most unconjugated and tauroconjugated bile acids but not by glycoconjugated bile acids should be accounted for by mechanisms other than nonselective liver cell injury.
PMID: 7611405
Lipids. 2006 Sep;41(9):835-43
Deoxycholic acid formation in gnotobiotic mice associated with human intestinal bacteria.
Narushima S, Itoha K, Miyamoto Y, Park SH, Nagata K, Kuruma K, Uchida K.
Laboratory of Veterinary Public Health, Graduate School of Agricultural and Life Sciences, The University of Tokyo, Bunkyo, Tokyo 113-8657, Japan.
In humans and animals, intestinal flora is indispensable for bile acid transformation. The goal of our study was to establish gnotobiotic mice with intestinal bacteria of human origin in order to examine the role of intestinal bacteria in the transformation of bile acids in vivo using the technique of gnotobiology. Eight strains of bile acid-deconjugating bacteria were isolated from ex-germ-free mice inoculated with a human fecal dilution of 10(-6), and five strains of 7alpha-dehydroxylating bacteria were isolated from the intestine of limited human flora mice inoculated only with clostridia. The results of biochemical tests and 16S rDNA sequence analysis showed that seven out of eight bile acid-deconjugating strains belong to a bacteroides cluster (Bacteroides vulgatus, B. distasonis, and B. uniformis), and one strain had high similarity with Bilophila wadsworthia. All five strains that converted cholic acid to deoxycholic acid had greatest similarity with Clostridium hylemonae. A combination of 10 isolated strains converted taurocholic acid into deoxycholic acid both in vitro and in the mouse intestine. These results indicate that the predominant bacteria, mainly Bacteroides, in human feces comprise one of the main bacterial groups for the deconjugation of bile acids, and clostridia may play an important role in 7aplha-dehydroxylation of free-form primary bile acids in the intestine although these strains are not predominant. The gnotobiotic mouse with bacteria of human origin could be a useful model in studies of bile acid metabolism by human intestinal bacteria in vivo.
PMID: 17152920
http://www.ingentaconnect.com/content/cabi/bjn/1989/00000062/00000003/art00005;jsessionid=2e953w9ke2hvh.alice?
Bile acid conjugation and hepatic taurine concentration in rats fed on pectin
Authors: Ide, T.1; Horii, M.1; Kawashima, K.1; Yamamoto, T.1
Source: British Journal of Nutrition, Volume 62, Number 3, November 1989 , pp. 539-550(12)
Publisher: CABI Publishing
A relationship between bile acid conjugation and hepatic taurine concentration was investigated in rats fed on citrus pectin. When rats were fed on the diets containing varying amounts of pectin (10, 30, 60 and 100 g/kg dietary levels), biliary excretion of bile acids increased as the dietary levels of pectin increased. The increase was entirely due to the glycine-conjugated bile acids. The biliary excretion of taurine-conjugated bile acid was somewhat decreased as the dietary level of the fibre increased. Consequently, most of the bile acids were conjugated with glycine in rats fed on the diet containing 100 g pectin/kg. On the other hand, dietary cellulose (60 and 100 g/kg) did not affect the biliary bile acid excretions. The major proportion of bile acids in rats receiving a fibre-free diet and the diets containing cellulose were conjugated with taurine. Hepatic taurine concentrations decreased as the dietary levels of pectin, but not of cellulose, increased. Although dietary pectin (100 g/kg) also slightly decreased the taurine concentration in the kidney, those concentrations in other non-hepatic tissues examined (heart, brain and serum) were unaffected by the dietary fibre. Supplementation of the diet containing 100 g pectin/kg with methionine (10 g/kg) and taurine (10 and 50 g/kg) strikingly increased hepatic taurine concentrations. In this situation, the conjugation of bile acid with glycine was almost abolished and taurine conjugates became abundant in the bile of these animals. It is suggested that dietary pectin mediated an increase in the biliary bile acid excretion which may have depleted the hepatic pool of taurine available for bile acid conjugation and, thus, increased glycine conjugation of bile acids.
Keywords: Bile acid conjugation; Pectin; Taurine; Rat
Document Type: Research article
DOI: 10.1079/BJN19890056
Affiliations: 1: Laboratory of Nutrition Chemistry, National Food Research Institute, Ministry of Agriculture, Forestry and Fisheries, Tsukuba Science City, 305, Japan
Folia Microbiol (Praha). 2006;51(4):306-8
Effect of chitosan on the growth of human colonic bacteria.Simůnek J, Tishchenko G, Hodrová B, Bartonová H.Institute of Animal Physiology and Genetics, Academy of Sciences of the Czech Republic, Prague, Czechia. simunek@iapg.cas.cz
Growth of 6 bacterial strains representing dominant members of the human colonic microflora was measured in the presence of 0.025, 0.05 and 0.5 % chitosan (from shrimp shells, with a 97 % final degree of deacetylation). The effect of chitosan was variable and dependent on bacterial species. The most susceptible to chitosan were bacteria belonging to genera Bacteroides and Clostridium (91-97% growth inhibition). On the other hand, Roseburia sp., Eubacterium sp. and Faecalibacterium sp. were more resistant (63-83 % inhibition of growth). Chitosan can thus be considered as one of the means for influencing the bacterial population in the human colon.PMID: 17007432
Exp Toxicol Pathol. 2003 Jun;54(5-6):381-6Influence of ethinyloestradiol propanolsulphonate on serum bile acids in healthy volunteers.
Barth A, Klinger G, Rost M.Institute of Pharmacology and Toxicology, Friedrich Schiller University Jena, Germany. Astrid.Barth@mti-n.uni-jena.de
The present work was done to clarify the relevance of altered serum bile acid (BA) profile in healthy women after the administration of the depot oestrogen ethinyloestradiol propanolsulphonate (EES). In the serum of 20 healthy women before and two times after oral EES application, 11 free and 14 taurine- and glycine-conjugated BA were analysed by HPLC with postcolumn derivatisation and fluorescence detection. EES significantly enhanced the total serum BA concentration and that of taurine-conjugated BAs, more pronounced the secondary BAs taurodeoxycholic, tauroursodeoxycholic and taurolithocholic acid. These secondary BAs are produced in the intestine by bacteria due to 7alpha-dehydroxylation of the primary BAs cholic and chenodeoxycholic acid. Because of unchanged free BAs, also produced by intestinal bacteria due to deconjugation, the results were interpreted as a sign of disturbed transport of BAs into the liver. Inhibition of the liver Na(+)-bile salt co-transporter (Ntcp) in the sinusoidal membrane by ethinyloestradiol, formed from the prodrug EES, may be responsible for the altered BA profile in serum.
PMID: 12877349
Res Microbiol. 2006 Nov;157(9):876-84
Effect of tea phenolics and their aromatic fecal bacterial metabolites on intestinal microbiota.
Lee HC, Jenner AM, Low CS, Lee YK.Department of Microbiology, National University of Singapore, 5 Science Drive 2, Singapore 117597, Republic of Singapore.
Tea is rich in polyphenols and other phenolics that have been widely reported to have beneficial health effects. However, dietary polyphenols are not completely absorbed from the gastrointestinal tract and are metabolized by the gut microflora so that they and their metabolites may accumulate to exert physiological effects. In this study, we investigated the influence of the phenolic components of a tea extract and their aromatic metabolites upon bacterial growth. Fecal homogenates containing bacteria significantly catalyzed tea phenolics, including epicatechin, catechin, 3-O-methyl gallic acid, gallic acid and caffeic acid to generate aromatic metabolites dependent on bacterial species. Different strains of intestinal bacteria had varying degrees of growth sensitivity to tea phenolics and metabolites. Growth of certain pathogenic bacteria such as Clostridium perfringens, Clostridium difficile and Bacteroides spp. was significantly repressed by tea phenolics and their derivatives, while commensal anaerobes like Clostridium spp., Bifidobacterium spp. and probiotics such as Lactobacillus sp. were less severely affected. This indicates that tea phenolics exert significant effects on the intestinal environment by modulation of the intestinal bacterial population, probably by acting as metabolic prebiotics. Our observations provide further evidence for the importance of colonic bacteria in the metabolism, absorption and potential activity of phenolics in human health and disease. The bioactivity of different phenolics may play an important role in the maintenance of gastrointestinal health.
PMID: 16962743
Nerissa
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