Colonic bacterial activity, biliary cholesterol saturation, and pathogenesis of gallstones

The relation between colonic bacterial metabolites in bile and saturation of bile with cholesterol was investigated. Eleven healthy men ingested metronidazole (2 g daily) for 10 days to inhibit anaerobic bacterial activity. Bile composition was determined in fasting samples aspirated from the duodenum before metronidazole was given, at the end of 10 days on metronidazole, and a month after the drug was discontinued. Bile cholesterol saturation fell in ten of the eleven subjects from a mean of 1.00 to 0.83 and rose in all eleven after the drug was stopped. At the same time the proportion of deoxycholate in bile acid decreased from a mean of 24% to 7%, returning to 22% of the total a month after metronidazole had been stopped, and the proportion of chenodeoxycholate changed significantly from 33% to 46% and back to 33%. There was little change in cholate concentrations. Deoxycholate is formed exclusively by bacterial action in the colon. Its administration increases cholesterol saturation of bile, while chenodeoxycholate reduces it. These results suggest that colonic function is important in regulating bile composition. Dietary measures which reduce the return of newly formed deoxycholate from the colon to the bile reduce cholesterol saturation and so are likely to reduce the risk of gallstones.

Dissolution of gallstones in hamsters by 3-hydroxy-3-methylglutaric acid

Addition of 0.05--0.20% of 3-hydroxy-3-methylglutaric acid to a lithogenic hamster diet resulted in a marked reduction in the incidence of gallstones in hamsters.

Effect of aging on biliary lipid composition and bile acid metabolism in normal Chilean women

Biliary lipid composition was determined in fasting gallbladder bile of 12 young and 12 elderly asymptomatic Chilean women with normal weights and recent, normal cholecystograms. The proportion of biliary cholesterol and the lithogenic index were significantly higher in elderly females. Moreover, supersaturated bile was present in 8.3% of the young and in 41.7% of the older women studied. Obesity enhances the saturation of bile in older females: lithogenic bile was found in 100% of 4 elderly, obese women with radiologically normal gallbladders. The bile acid pool and cholic acid metabolism were studied in 5 young and 4 older normal females. Both groups showed similar values of bile acid pool, cholic acid synthesis, and turnover. These results indicate that aging per se modifies the proportions of biliary lipids in Chilean women, and provide a partial explanation for the frequency of gallstones observed among them. The increment in the lithogenic index of gallbladder bile with age takes place without significant changes in bile acid metabolism, suggesting that the canalicular secretion of cholesterol increases with aging.

Physical exercise and the prevention of atherosclerosis and cholesterol gall stones

There is accumulating evidence in man and experimental animals that even mild exercise, if regularly repeated, may alter the metabolism of lipids. Exercise has been reported as decreasing peripheral tissue cholesterol in red blood cells, working muscle, lungs and the liver. During physical activity, the output of cholesterol and bile acids into the bile increases. This probably leads to higher faecal losses of sterols which may lead to lower cholesterol levels in the peripheral tissues and in the bile, when exercise is repeated regularly. Preferential release of unsaturated fatty acids from the adipose tissue during exercise and the linoleic acid-dependent LCAT enzyme (transporting plasma cholesterol) may be partly responsible for this effect of exercise. The experimental data reviewed provide supportive basis for epidemiological studies reporting on the beneficial effect of regular exercise.

Physical activity is an important factor in the phylogeny of all animal species, secondary only to food intake and reproduction. Exercise is readily available to all population groups. There is good evidence that the amount of exercise required for a protective effect is easily accessible for time-pressured and older individuals. Short bursts of activity repeated several times a day may be equally or more beneficial than prolonged exhaustive exercise. Modified exercise is also beneficial for patients with coronary heart disease and for elderly patients, provided this is done under strict medical supervision. To be effective, physical exercise should be regular and continuous throughout life.

The effect of added bran to the diet on the saturation of bilein people without gallstones

Bran was added to the diet of eleven volunteers without gallstones, and its effect on bile saturation, bile acid profile in bile, and serum cholesterol and triglycerides was determined. Bile cholesterol saturation was decreased after two months of feeding bran to those female subjects who had supersaturated bile. Bran may be effective in decreasing the lithogenic potential of bile in people without gallstones, and further studies on its place in the prevention of gallstones in susceptible individuals are indicated.

Feasibility of low-dose and intermittent chenodeoxycholic acid therapy of gallstones

Chenodeoxycholic acid, by reducing the concentration of biliary cholesterol relative to that of bile acid and phospholipid, dissolves cholesterol gallstones. This bile acid, however, has potential dose-related hepatotoxicity and causes dose-related diarrhea. Therefore, the feasibility of low-dose and intermittent therapy was assessed by studying the induction and persistence of chenodeoxycholic acid-induced biliary lipid changes. Biliary lipid composition with each of 3 doses of chenodeoxycholic acid was determined in bile samples obtained by cholecystokinin-stimulated duodenal drainage before, after one week and one month of treatment, and up to 9 weeks after discontinuation of treatment. The lowest dose that significantly reduced the relative concentration of biliary cholesterol was 250 mg/day. A significant reduction occurred one week after initiation of treatment and was maintained for 9 weeks following discontinuation of treatment. Thus, clinical trials on low-dose and intermittent chenodeoxycholic acid therapy for gallstone prophylaxis or dissolution are warranted.

Reduction of gallstone formation by ascorbic acid in hamsters

The addition of 0.5% of ascorbic acid to the lithogenic diet of golden hamsters whose body pool was labelled with 26-14C-cholesterol, lowered the formation of gallstones, the cholesterol concentration and half-life in blood plasma and in the liver, and accelerated cholesterol transformation to bile acids.

Effect of phenobarbital on biliary lipid metabolism in normal man

The efficacy of phenobarbital in altering biliary lipid composition in normal man was investigated by determining parameters of biliary lipid metabolism in 8 human subjects without biliary tract disease before and after oral phenobarbital administration at a dose of approximately 3 mg per kg per day for 25 to 54 days. In 8 subjects studied, phenobarbital did not produce any statistically significant changes in the following parameters: bile lipid composition, cholesterol saturation index, total bile acid pool size, daily fractional turnover rate of cholic acid, hepatic secretion rates of cholesterol, bile acids, or phospholipids, and the fraction of the total bile acid pool represented by individual bile acids. Therefore, phenobarbital is not an effective agent, at least when used alone, in inducing changes in bile lipid composition during a short term of administration in normal man. This would indicate that phenobarbital would not be a useful modality in the prevention of the development of cholesterol gallstones, but its prophylactic value in subjects with bile of higher lithogenicity cannot be predicted from these studies.

[Treatment of intrahepatic cholesterol stones by chenodeoxycholic acid (author's transl)]

Intrahepatic gallstones were demonstrated by operative cholangiography in two men, aged 34 and 46 years, respectively. The cholesterol stones were dissolved in both patients within eight and two months, respectively, by retrograde instillation of chendeoxycholic acid via a T-drain. Additional endoscopic papillotomy was performed because of a papillary stenosis in one instance, and extrahepatic occlusion during treatment in the other. During treatment there was a rise of transaminases of 5-fold levels, of gamma-glutamyl transferase up to 10-fold of normal. Since chenodeoxycholic-acid instillations both patients have been receiving the drug orally to prevent recurrence of gallstones. So far all biochemical values are within the normal range, the patients are without symptoms and have a normal exercise tolerance.

Prevention of gallstone formation in rabbits by the oral administration of kanamycin

Rabbits fed a diet containing 40 per cent casein, 15 per cent oleic acid and 45 per cent laboratory pellets developed glycoallodeoxycholic acid and glycodeoxycholic acid gallstones. The oral administration of kanamycin prevented allo bile acid stone formation in the oleic acid fed rabbit without leading to cholesterol gallstone formation. Kanamycin reduced the concentration of allodeoxycholic acid in the bile of oleic acid fed rabbits from 16.6+/-4.1 per cent of total bile acids to 1.1+/-1.1 per cent, with a reciprocal increase in deoxycholic acid concentration. The allodeoxycholate concentration was far below that found in control bile samples, 10.2+/-2.3 per cent. If the effect of kanamycin on the bile composition is by its antibiotic action, this eliminates the importance of a hepatic contribution to allodeoxycholate stone formation.

Definition of dietary fiber and hypotheses that it is a protective factor in certain diseases

Crude fiber (CF) is the residue of plant food left after extraction by dilute acid followed by dilute alkali. Dietary fiber (DF), a new term, is the residue of plant food resistant to hydrolysis by human alimentary enzymes. DF is composed of cellulose, hemicellulose, and lignin; these constituents are not reported in food tables. For instance, whole wheatmeal has DF about 11%, CF about 2%. It is suggested that a new term, dietary fiber complex (DFC), should include all substances of DF plus all chemical compounds naturally associated with, and concentrated around, these structural polymers. CF supplies from starchy staples, wheat and potato, in England and Wales were probably stationary from 1770 to 1860, fell greatly from 1860 to 1910, rose during food controls in 1942 to 1953, and declined slightly from 1954 to 1970. It is postulated that fiber is a protective factor against certain colonic disorders, such as diverticular disease, and certain metabolic diseases, such as ischemic heart disease, diabetes mellitus, and obesity. These three diseases had changing trends of mortality rates in England during the food control years. Westernization of African diets is accompanied by a large fall in CF from starchy foods and vegetables and an increased prevalence of the same three diseases.

Effect of Beta-sitosterol on cholesterol-cholic acid-induced gallstone formation in mice

Beta-sitosterol has been shown to prevent gallstone formation in mice fed 1.2% cholesterol and 0.5% cholic acid (lithogenic diet). The incidence of gallstone formation in the mouse by the addition of 2.5% sitosterol in the lithogenic diet is about 35.5% in male and 25% in female. The condition of the liver, whether fatty or normal, did not correlate with the presence or absence of cholelithiasis. The serum and liver cholesterol levels of mice fed either sitosterol and cholesterol or sitosterol and cholic acid is lower than those of mice fed cholesterol or cholic acid alone. Elevation of liver phospholipid concentration was noticed in mice fed sitosterol or a combination of sitosterol with cholesterol or cholic acid or both cholesterol and cholic acid.

Effect of dietary fibre on gallstone formation in hamsters

This study aimed at investigating the effect of different sources of dietary fibre on gallstone formation in hamsters. The substances studied were pectin, lignin and psyllium hydrocolloid. The two latter compounds protected hamsters against cholesterol gallstone formation. Lignin resulted in a decrease of the deoxycholic acid conentration and in a rise of the cholic/chenodeoxycholic acid ratio. These changes which are similar to those observed with cholestyramine suggest that lignin acts as a bile acid sequestrant. Psyllium hydrocolloid effected a similar shift of the cholic/chenodeoxycholic acid ratio but it also resulted in a rise of the deoxycholic concentration. This latter finding is not compatible with a bile acid sequestering role of this compound. The addition of alcohol to the drinking-water resulted in the formation of stones rich in pigment. Under these conditions the tendency to form such stones was not checked by either of the investigated substances.