Position of the American Dietetic Association: health implications of dietary fiber

Dietary fiber consists of the structural and storage polysaccharides and lignin in plants that are not digested in the human stomach and small intestine. A wealth of information supports the American Dietetic Association position that the public should consume adequate amounts of dietary fiber from a variety of plant foods. Recommended intakes, 20-35 g/day for healthy adults and age plus 5 g/day for children, are not being met, because intakes of good sources of dietary fiber, fruits, vegetables, whole and high-fiber grain products, and legumes are low. Consumption of dietary fibers that are viscous lowers blood cholesterol levels and helps to normalize blood glucose and insulin levels, making these kinds of fibers part of the dietary plans to treat cardiovascular disease and type 2 diabetes. Fibers that are incompletely or slowly fermented by microflora in the large intestine promote normal laxation and are integral components of diet plans to treat constipation and prevent the development of diverticulosis and diverticulitis. A diet adequate in fiber-containing foods is also usually rich in micronutrients and nonnutritive ingredients that have additional health benefits. It is unclear why several recently published clinical trials with dietary fiber intervention failed to show a reduction in colon polyps. Nonetheless, a fiber-rich diet is associated with a lower risk of colon cancer. A fiber-rich meal is processed more slowly, which promotes earlier satiety, and is frequently less calorically dense and lower in fat and added sugars. All of these characteristics are features of a dietary pattern to treat and prevent obesity. Appropriate kinds and amounts of dietary fiber for the critically ill and the very old have not been clearly delineated; both may need nonfood sources of fiber. Many factors confound observations of gastrointestinal function in the critically ill, and the kinds of fiber that would promote normal small and large intestinal function are usually not in a form suitable for the critically ill. Maintenance of body weight in the inactive older adult is accomplished in part by decreasing food intake. Even with a fiber-rich diet, a supplement may be needed to bring fiber intakes into a range adequate to prevent constipation. By increasing variety in the daily food pattern, the dietetics professional can help most healthy children and adults achieve adequate dietary fiber intakes.

A multicenter, placebo-controlled, randomized, double-blind, prospective trial of prophylactic ursodiol for the prevention of gallstone formation following gastric-bypass-induced rapid weight loss

BACKGROUND

Previous studies have documented a high incidence of gallstone formation following gastric-bypass (GBP)-induced rapid weight loss in morbidly obese patients. This study was designed to determine if a 6-month regimen of prophylactic ursodiol might prevent the development of gallstones.

METHODS

A multicenter, randomized, double-blind, prospective trial evaluated 3 oral doses of ursodiol: 300, 600, and 1,200 mg versus placebo beginning within 10 days after surgery and continuing for 6 months or until gallstone development, for patients with a body mass index (BMI) > or = 40 kg/m2. All patients had normal intraoperative gallbladder sonography. Transabdominal sonography was obtained at 2, 4, and 6 months following surgery, or until gallstone formation.

RESULTS

Of 233 patients with at least one postoperative sonogram, 56 were randomized to placebo, 53 to 300 mg ursodiol, 61 to 600 mg ursodiol, and 63 to 1,200 mg ursodiol. Preoperative age, sex, race, weight, BMI, and postoperative weight loss were not significantly different between groups. Gallstone formation occurred at 6 months in 32%, 13%, 2%, and 6% of the patients on the respective doses. Gallstones were significantly (P < 0.001) less frequent with ursodiol 600 and 1,200 mg than with placebo.

CONCLUSION

A daily dose of 600 mg ursodiol is effective prophylaxis for gallstone formation following GBP-induced rapid weight loss.

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.

Nutritional and metabolic complications of bariatric surgery

Bariatric surgery is an effective treatment for patients with clinically severe obesity. In addition to significant weight loss, it is also associated with improvements in comorbidities. Unfortunately, bariatric surgery also has the potential to cause a variety of nutritional and metabolic complications. These complications are mostly due to the extensive surgically induced anatomical changes incurred by the patient's gastrointestinal tract, particularly with roux-en-Y gastric bypass and biliopancreatic diversion. Complications associated with vertical banded gastroplasty are mostly due to decreased intake amounts of specific nutrients. Macronutrient deficiencies can include severe protein-calorie malnutrition and fat malabsorption. The most common micronutrient deficiencies are of vitamin B12, iron, calcium, and vitamin D. Other micronutrient deficiencies that can lead to serious complications include thiamine, folate, and the fat-soluble vitamins. Counseling, monitoring, and nutrient and mineral supplementation are essential for the treatment and prevention of nutritional and metabolic complications after bariatric surgery.

Aspirin prevention of cholesterol gallstone formation in prairie dogs

When prairie dogs (Cynomys ludovicianus) are fed a diet containing cholesterol, a marked increase in gallbladder mucin secretion parallels the evolution of cholesterol supersaturated bile. Gelation of mucin precedes the precipitation of cholesterol liquid and solid crystals and the development of gallstones. Aspirin given to prairie dogs inhibited mucin hypersecretion and gel accumulation and prevented gallstone formation without influencing the cholesterol content of supersaturated bile. This suggests that gallbladder mucin is a nucleation matrix for cholesterol gallstones.

Effects of ursodeoxycholic acid and aspirin on the formation of lithogenic bile and gallstones during loss of weight

We attempted to determine whether the administration of aspirin or ursodeoxycholic acid during loss of weight could prevent the development of lithogenic changes in bile and the formation of gallstones. Sixty-eight obese subjects without gallstones who were entered in a program (520 kcal per day) to lose weight were randomly assigned to receive ursodeoxycholic acid (1200 mg per day), aspirin (1300 mg per day), or placebo in double-blind fashion for up to 16 weeks. At entry, at four weeks of treatment, and at three weeks after the completion of treatment, the subjects underwent ultrasonography to detect gallstones and duodenal drainage of bile to detect cholesterol crystals and to determine the bile saturation index and glycoprotein concentration. No gallstones or cholesterol crystals formed in the patients treated with ursodeoxycholic acid. Among the patients given placebo, gallstones formed in five (P less than 0.05 vs. ursodeoxycholic acid) and cholesterol crystals in six (P less than 0.001 vs. ursodeoxycholic acid); among those given aspirin, gallstones formed in two and cholesterol crystals in one (no significant difference from ursodeoxycholic acid treatment). By the fourth week, the bile saturation index increased in the placebo group (from 1.07 +/- 0.26 to 1.29 +/- 0.27; P less than 0.001), decreased in the ursodeoxycholic acid group (from 1.11 +/- 0.34 to 0.91 +/- 0.24; P less than 0.001), and did not change significantly in the aspirin group. The concentration of glycoprotein in bile increased in the placebo group (27.9 +/- 14.5 percent; P less than 0.001) but did not change significantly in the groups treated with ursodeoxycholic acid or aspirin. We conclude that ursodeoxycholic acid prevents lithogenic changes in bile and the formation of gallstones in obese subjects during loss of weight.

Contributions of obesity and weight loss to gallstone disease

OBJECTIVE

To examine the relation of obesity and weight loss to the formation of gallstones according to pertinent clinical and research issues.

DATA SOURCES AND EXTRACTION

Original reports obtained through a MEDLINE search from 1966 to 1992 on gallstones plus obesity or reducing diets, supplemented by a manual search of bibliographies, a Current Contents title search from 1991 to 1992 on gallstones and gallbladder, and expert opinion. Only studies of humans were cited.

DATA SYNTHESIS

For women, but less so for men, obesity is a strong risk factor for gallstones, and this risk is increased during weight loss. Between 10% and 25% of obese men and women may develop gallstones within a few months of beginning a very low calorie diet, and perhaps one third of these will develop symptoms of gallstones. Persons with the highest body mass index before weight loss and those who lose weight most rapidly appear to be at the greatest risk for gallstones. Treatment with ursodeoxycholic acid (ursodiol) during weight loss dieting is the only proven prevention for the formation of gallstones. Issues to be resolved include how different diets affect the risk for developing gallstones, the identification of other risk factors for gallstone formation during weight loss, the effect of weight loss among people with preexisting gallstones, and the optimum means of preventing gallstones during weight loss.

CONCLUSIONS

During weight loss, particularly among the obese, an increased risk exists for symptomatic gallstone formation. This acute risk offers the opportunity to investigate the cause of gallstones and possibly to prevent them.

Predictors of gallstone formation after bariatric surgery: a multivariate analysis of risk factors comparing gastric bypass, gastric banding, and sleeve gastrectomy

BACKGROUND

Risk factors for gallstone formation in the general population have been well studied while those after weight reduction surgery are unknown. The aim of this study was to identify the risk factors for the development of symptomatic gallstones after bariatric surgery.

METHOD

Retrospective review was performed for patients who underwent laparoscopic Roux-en-Y gastric bypass (RYGBP), adjustable gastric banding (LAGB) or sleeve gastrectomy (LSG) between 2004 and 2006. Statistical evaluation was performed using a univariate and multivariate analysis. Risk factors, including age, gender, preoperative body mass index (BMI), BMI > 45 kg/m(2), diabetes mellitus, hyperlipidemia, types of operation, and weight loss >25% of original weight, were analyzed for their association with postoperative symptomatic gallstones formation.

RESULTS

670 laparoscopic RYGBP, 47 LAGB, and 79 LSG were performed in our institute. Preoperative gallbladder disease, as indicated by presence of gallstones or sludge on preoperative transabdominal ultrasound, or previous cholecystectomy, were found in 25.3, 14.9, and 30.4% of patients who subsequently had RYGBP, LAGB, and LSG, respectively. A total of 586 patients were included for analysis. Mean follow-up was 25.9 (range 12-42) months. Overall rate of symptomatic gallstone formation was 7.8% and mean time for its development was 10.2 (range 2-37) months. Incidence of symptomatic gallstones with complications as initial presentation was found in 1.9% of the patients. Logistic regression analysis showed that only postoperative weight loss of more than 25% of original weight was associated with symptomatic gallstones formation [B = 1.482, SE = 0.533, odds ratio 4.44, 95% confidence interval (CI) 1.549-12.498, p = 0.005].

CONCLUSIONS

Traditional risk factors for gallstone formation in the general population are not predictive of symptomatic gallstone formation after bariatric surgery. Weight loss of more than 25% of original weight was the only postoperative factor that can help selecting patients for postoperative ultrasound surveillance and subsequent cholecystectomy once gallstones were identified.

Moderate alcohol intake reduces bile cholesterol saturation and raises HDL cholesterol

The effect of alcohol on plasma high-density lipoprotein (HDL) cholesterol and on bile cholesterol saturation was measured in 12 healthy volunteers with a very low initial alcohol intake who drank 39 g alcohol daily for six weeks, and then abstained from alcohol for 6 weeks. HDL cholesterol (mean +/- SEM) rose significantly from 1.07 +/- 0.05 to 1.25 +/- 0.08 mmol/l (41.4 +/- 1.9 to 48.3 +/- 3.1 mg/dl) when alcohol was being consumed and fell to 1.04 +/- 0.06 mmol/l (40.2 +/- 2.3 mg/dl) during abstention. Bile cholesterol saturation index fell from 1.31 +/- 0.06 to 1.08 +/- 0.06 during the period of alcohol consumption and rose to 1.27 +/- 0.09 during abstention. There was a significant inverse correlation between bile saturation index and HDL cholesterol (r = -0.56). These data provide further evidence of a biochemical link between cardiovascular disease and cholesterol gallstones and suggest that moderate alcohol intake has some protective effect against both diseases.

Recreational physical activity and the risk of cholecystectomy in women

BACKGROUND

Physical activity may be an important determinant of the risk of gallstone disease in women, both independently and as a result of its role in maintaining body weight.

METHODS

We prospectively studied recreational physical activity (such as jogging, running, and bicycling) and sedentary behavior (such as spending hours watching television) in relation to the risk of cholecystectomy, a surrogate for symptomatic cholelithiasis, in a cohort of 60,290 women who were 40 to 65 years of age in 1986 and had no history of gallstone disease. As part of the Nurses' Health Study, the women reported on questionnaires mailed to them every two years both their activity level and whether they had undergone cholecystectomy. During a 10-year follow-up period (1986 to 1996), 3257 cases of cholecystectomy were documented.

RESULTS

Recreational physical activity was inversely related to the risk of cholecystectomy. The multivariate relative risk for women in the highest as compared with the lowest quintile of physical activity was 0.69 (95 percent confidence interval, 0.61 to 0.78). In contrast, sedentary behavior was independently related to an increased risk of cholecystectomy. As compared with women who spent less than 6 hours per week sitting while at work or driving, women who spent 41 to 60 hours per week sitting had a multivariate relative risk of 1.42 (95 percent confidence interval, 1.06 to 1.89), and women who spent more than 60 hours per week sitting while at work or driving had a multivariate relative risk of 2.32 (95 percent confidence interval, 1.26 to 4.26). These associations persisted after we controlled for body weight and weight change.

CONCLUSIONS

In women, recreational physical activity is associated with a decreased risk of cholecystectomy. The association is independent of other risk factors for gallstone disease, such as obesity and recent weight loss.

Effect of ezetimibe on the prevention and dissolution of cholesterol gallstones

BACKGROUND & AIMS

Cholesterol cholelithiasis is one of the most prevalent and most costly digestive diseases in developed countries and its incidence has increased markedly in Asian countries owing to the adoption of Western-type dietary habits. Because animal experiments showed that high efficiency of intestinal cholesterol absorption contributes to gallstone formation, we explored whether the potent cholesterol absorption inhibitor ezetimibe could prevent gallstones and promote gallstone dissolution in mice and reduce biliary cholesterol content in human beings.

METHODS

Male gallstone-susceptible C57L mice were fed a lithogenic diet and concomitantly administered with ezetimibe at 0, 0.8, 4, or 8 mg/kg/day for 8 or 12 weeks. Gallbladder biles and gallstones were examined by microscopy. Gallbladder emptying in response to cholecystokinin octapeptide was measured gravimetrically. Biliary lipid outputs were analyzed by physical-chemical methods. Cholesterol absorption efficiency was determined by fecal dual-isotope ratio and mass balance methods. Lipid changes in gallbladder biles of gallstone patients vs overweight subjects without gallstones were examined before (day 0) and at 30 days after ezetimibe treatment (20 mg/day).

RESULTS

Ezetimibe prevented gallstones by effectively reducing intestinal cholesterol absorption and biliary cholesterol secretion, and protected gallbladder motility function by desaturating bile in mice. Treatment with ezetimibe promoted the dissolution of gallstones by forming an abundance of unsaturated micelles. Furthermore, ezetimibe significantly reduced biliary cholesterol saturation and retarded cholesterol crystallization in biles of patients with gallstones.

CONCLUSIONS

Ezetimibe is a novel approach to reduce biliary cholesterol content and a promising strategy for preventing or treating cholesterol gallstones by inhibiting intestinal cholesterol absorption.

Genetics of responsiveness to high-fat and high-cholesterol diets in the mouse

The natural variation among inbred strains of mice was used to elucidate the genetic factors underlying the responsiveness to high-fat and high-cholesterol diets. The nine strains examined are the progenitors of recombinant inbred strain sets: C57BL/6J, C57L/J, SWR/J, SJL/J, SM/J, A/J, AKR/J, C3H/HeJ, and DBA/2J. Plasma lipids, liver lipids, the prevalence of cholesterol gallstones, and the size of aortic fatty streak lesions were examined after 18 wk of consumption of the diet containing 15% fat and 1% cholesterol. The variation in aortic lesions found among inbred strains provided the basis for several additional studies that demonstrated the existence of eight genes affecting atherosclerosis. These genes, named Ath1 to Ath8, are briefly described. The genetic analysis of variation in gallstone formation demonstrated that more than one gene affects this phenotype.

The relation of physical activity to risk for symptomatic gallstone disease in men

BACKGROUND

Gallstone disease is a major source of morbidity in the United States. Gallstones are twice as common in women as in men, but severe biliary events leading to surgery occur with equal frequency in the two sexes.

OBJECTIVE

To determine whether physical activity decreases risk for symptomatic gallstone disease in men.

DESIGN

Prospective cohort study.

SETTING

U.S. male health professionals.

PATIENTS

45,813 men 40 to 75 years of age were followed from 1986 to 1994.

MEASUREMENTS

Questionnaires mailed in 1986, 1988, 1990, 1992, and 1994 asked about physical activity, incidence of gallstone disease, age, body weight, dietary and alcohol intake, smoking habits, use of medications, and occurrence of diagnosed medical conditions other than gallstone disease.

RESULTS

828 men reported having newly symptomatic gallstones (diagnosed by ultrasonography or radiography) or undergoing cholecystectomy for recent symptoms. After adjustment for multiple confounders, increased physical activity was inversely related to risk for symptomatic gallstone disease. When extreme quintiles were compared, men younger than 65 years of age had a stronger inverse association (multivariate relative risk, 0.58 [95% CI, 0.44 to 0.78]) with risk than did men 65 years of age or older (relative risk, 0.75 [CI, 0.52 to 1.09]). In contrast, sedentary behavior was positively related to risk for symptomatic gallstone disease. Men who watched television more than 40 hours per week had a higher risk for symptomatic gallstones than men who watched less than 6 hours per week (relative risk for older men, 3.32 [CI, 1.51 to 7.27]; relative risk for younger men, 1.58 [CI, 0.38 to 6.48]).

CONCLUSIONS

Physical activity may play an important role in the prevention of symptomatic gallstone disease in men even beyond its benefit for control of body weight. The results of this study indicate that 34% of cases of symptomatic gallstone disease in men could be prevented by increasing exercise to 30 minutes of endurance-type training five times per week.

Prevention of gallstone formation in morbidly obese patients undergoing rapid weight loss: results of a randomized controlled pilot study

INTRODUCTION

An increased risk of gallstone (GS) formation has been linked to obesity and to episodes of rapid and significant weight loss. Previous reports have suggested that bile salt therapy (ursodeoxycholic acid) or prostaglandin inhibition (ibuprofen) may prevent gallstone formation in this high-risk group. The purpose of this study was to investigate GS prevention following bariatric surgery.

DESIGN

Randomized double blind controlled trial.

METHODS

Sixty patients without gallstones preoperatively (gender, 9 male, 51 female; average preop wt, 349.6 lb; mean age, 38 years) were randomly assigned to receive urso (600 mg/day, n = 20), ibuprofen (600 mg/d, n = 20), or placebo (n = 20). At the time of standard open gastric bypass, intraoperative ultrasonography confirmed the absence of stones or microcalculi, and bile samples were collected via puncture of the gallbladder for bile lipid analysis. Following recovery and resumption of a bariatric diet, study medication was prescribed for the first 6 months postop. Gallbladder emptying and GS formation were assessed using ultrasonograms preop and at 3, 6, 9, and 12 months postop (gallbladder emptying following a high-fat liquid test meal was assessed preop, and at 3 and 6 months postop).

RESULTS

Forty-one (68.3%, 8 male, 33 female) of the original 60 patients completed all phases of the study (15 urso, 15 ibuprofen, 11 placebo). The average weight loss was 98.5 +/- 7.2 lb over the 12-month period following bariatric surgery. Twenty-nine (71%) of 41 patients who completed the study developed GS. Of those who formed stones, 12 (41%) developed symptomatic GS and 8/12 (67%) underwent cholecystectomy (4 refused operation). Preoperative gallbladder emptying studies showed no differences in emptying between groups (urso 29%, ibuprofen 32%, and placebo 30%). There was no correlation found between the cholesterol saturation index (CSI mean 205.15, range 67-360) and the incidence of GS. There was a statistical difference (P < 0.01) between the ursodeoxycholic acid group and the ibuprofen group with respect to the incidence of stone formation. There was correlation between weight loss (mean 99 lb, range 21-278 lb) and GS formation, in that patients who lost more weight had a greater tendency to form gallstones. Complete medical compliance was achieved in only 17/60 (28%) of patients originally enrolled.

CONCLUSIONS

This pilot study confirms the high incidence of gallstone formation (71% of assessed patients) associated with rapid weight loss in patients undergoing gastric bypass. Despite active enrollment in a supervised prevention trial, the two therapies investigated to reduce gallstone formation were not efficacious, likely because compliance with medical therapy was poor. These findings highlight the significant risk of gallstone formation in this patient cohort even when prevention strategies are utilized.

Prophylaxis against gallstone formation with ursodeoxycholic acid in patients participating in a very-low-calorie diet program

OBJECTIVE

To determine whether prophylactic treatment with ursodeoxycholic acid can prevent gallstone formation in persons participating in a very-low-calorie weight reduction diet program.

DESIGN

Multicenter, double-blind, placebo-controlled, multidose clinical trial. Patients were treated with placebo or with 300 mg/d, 600 mg/d, or 1200 mg/d of ursodeoxycholic acid.

SETTING

31 Health Management Resources weight management centers.

PATIENTS

1004 patients were initially enrolled in a 16-week, 520-kcal/d, Health Management Resources liquid protein diet program. All patients had a body mass index of 38 kg/m2 or more and a normal gallbladder ultrasonogram before study entry. Bile analysis was done in 32 patients.

MEASUREMENTS

Body weight and body mass index were measured before the diet was started and at 2-week intervals for 16 weeks. Gallbladder ultrasonography was done before enrollment and after 8 and 16 weeks of dieting. Bile was obtained by endoscopy and analyzed for cholesterol crystals and lipid levels.

RESULTS

Mean body weight for all patients at the start of dieting was 128.2 kg +/- 23.2 kg; mean initial body mass index was 44.2 kg/m2 +/- 6.0 kg/m2. Gallstones developed in 28% (95% CI, 22% to 35%) of patients receiving placebo, in 8% (CI, 5% to 13%) of patients treated with 300 mg/d of ursodeoxycholic acid, in 3% (CI, 1% to 7%) of patients treated with 600 mg/d of ursodeoxycholic acid, and in 2% (CI, 0.5% to 5%) of patients treated with 1200 mg/d of ursodeoxycholic acid. The differences between patients receiving placebo and patients receiving ursodeoxycholic acid were statistically significant. The percentage of ursodeoxycholic acid in bile increased stepwise with increasing doses of ursodeoxycholic acid.

CONCLUSIONS

Ursodeoxycholic acid, 600 mg/d, is highly effective in preventing gallstone formation in patients having dietary-induced weight reduction.

Transgenic expression of cholesterol-7-alpha-hydroxylase prevents atherosclerosis in C57BL/6J mice

C57BL/6J mice are susceptible to atherosclerosis when fed a diet consisting of fat, cholesterol, and taurocholate. The susceptibility to diet-induced atherosclerosis is linked to a reduction in plasma high density lipoprotein (HDL). Diet-induced reduction of plasma HDL shows a physiological and a genetic correlation with repression of cholesterol-7-alpha-hydroxylase, the liver-specific enzyme that regulates the conversion of cholesterol into bile acids. To examine the hypothesis that the repression of cholesterol-7-alpha-hydroxylase is responsible for initiating the metabolic alterations leading to the formation of atherosclerosis and gallstones, we determined whether constitutive transgenic expression of cholesterol-7-alpha-hydroxylase in C57BL/6J mice would confer resistance to these 2 common human diseases. When fed the atherogenic diet, nontransgenic littermates, but not cholesterol-7-alpha-hydroxylase transgenic mice, accumulated cholesterol and cholesterol esters in their livers and plasma. Although the atherogenic diet caused a marked decrease in plasma HDL cholesterol in nontransgenic mice, HDL levels in transgenic mice remained relatively unchanged. Moreover, the ability of cholesterol-7-alpha-hydroxylase transgenic mice to maintain cholesterol and lipoprotein homeostasis completely prevented the formation of atherosclerosis and gallstones. These data establish the integral role that cholesterol-7-alpha-hydroxylase has in maintaining hepatic cholesterol homeostasis and, thus, in the susceptibility to the formation of gallstones and atherosclerosis.

Medically safe rate of weight loss for the treatment of obesity: a guideline based on risk of gallstone formation

OBJECTIVE

Currently recommended rates of weight loss for obese persons are not based on demonstrated health risks. The authors attempt to determine a medically safe rate of weight loss based on currently available data on the risk of gallstone formation during active weight loss.

METHODS

All prospective studies published in the English language on the formation of gallstones in obese persons during active weight loss were reviewed and evaluated. A statistical analysis was performed using studies of at least 4 weeks' duration that included information on diet composition, rates of weight loss, length of follow-up, and incidence of gallstone formation. A statistical model was fit to the data from the studies that met the criteria.

RESULTS

Nine subject groups derived from five published reports met the criteria for inclusion in the analysis. When the results of these groups were evaluated statistically, a curvilinear relationship between incidence of gallstone formation and rate of weight loss was demonstrated. The relationship was best described by an exponential regression curve, with an adjusted r2 of 0.98 and a dramatically increasing risk of gallstone formation at rates of weight loss above 1.5 kg per week.

CONCLUSION

Risk of gallstone formation in obese persons during active weight loss seems to increase in an exponential fashion. The data suggest that rates of weight loss should not exceed an average of 1.5 kg per week.

Gallbladder management in obesity surgery

BACKGROUND

In the 1980s, some surgeons recommended routine cholecystectomy for patients undergoing bariatric surgery. This was based on the high prevalence of gallstones in the obese and concern that rapid weight loss would increase the risk of gallbladder disease. Others recommended waiting for a lower weight and a definite need. With increasing prevalence and severity of obesity and increased use of gastric reduction surgery for weight control, it seemed appropriate to review the current standard of care for cholecystectomy. A survey was also made of ursodeoxycholic acid usage for prevention of gallstone formation.

METHODS

Data collected from active contributors for the 28th Report of the International Bariatric Surgery Registry (IBSR) were examined. Two questionnaires were also sent to members of the American Society for Bariatric Surgery (ASBS). The first (Q1) asked about the indications for cholecystectomy. The second (Q2) asked about ursodeoxycholic acid usage for prevention of gallstone formation during rapid weight loss following surgical treatment of obesity.

RESULTS

There has been an increase in concurrent cholecystectomy during the last 15 years. Some of this is due to a shift from simple gastric restrictive operations to gastric bypass with gastric restriction. When the most extensive bypass of intestine is used, as in distal Roux-en-Y gastric bypass (RYGBP-X) or biliopancreatic diversion with a duodenal switch (BPD-DS), all patients were reported to have undergone cholecystectomy. Only 30% of surgeons performing standard Roux-en-Y gastric bypass (RYGBP) remove normal-appearing gallbladders. Ursodeoxycholic acid is used to prevent gallstone formation in one-third of patients when a normal-appearing gallbladder is left in place.

CONCLUSIONS

Prophylactic cholecystectomy is left to the discretion of the surgeon when RYGBP is used. There has been an increase in cholecystectomy and malabsorptive operations during the last 15 years. When most of the small bowel is bypassed, all remaining gallbladders are removed. For patients with simple restriction operations, normal-appearing gallbladders are usually left in place. Urso-deoxycholic acid during rapid weight loss for prevention of gallstone formation is used in one-third of patients with remaining gallbladders.

Alcohol, wine, and health

BACKGROUND

For the past 20 years numerous epidemiological studies have correlated the consumption of alcohol and a variety of disease states: overall mortality, arteriosclerotic vascular diseases, hypertension, cancers, peptic ulcer, respiratory infections, gall stones, kidney stones, age-related macular degeneration, bone density, and cognitive function.

METHODS

A review of these articles reveals that each of these studies has compared the outcome of individuals at various levels of alcohol consumption with that of abstainers.

RESULTS

Each analysis has identified a U-shaped or J-shaped curve of reduced relative risk for a given disease state compared with abstainers. A clear definition of consumption in moderation becomes evident: for men it should not exceed 2 to 4 drinks per day, and for women it should not exceed 1 to 2 drinks per day.

CONCLUSIONS

Alcohol by itself has favorable effects on the level of high-density lipoprotein cholesterol, and inhibition of platelet aggregation. Wine, particularly red wine, has high levels of phenolic compounds that favorably influence multiple biochemical systems, such as increased high-density lipoprotein cholesterol, antioxidant activity, decreased platelet aggregation and endothelial adhesion, suppression of cancer cell growth, and promotion of nitric oxide production.

Diet and gallbladder cancer: a case-control study

Cancer of the gallbladder is rare but fatal, and has an unusual geographic and demographic distribution. Gallstones and obesity have been suggested as possible risk factors. As diet is known to influence both these factors, we carried out the present study to evaluate the possible role of diet in gallbladder carcinogenesis. A case-control study involving 64 newly diagnosed cases of gallbladder cancer and 101 cases of gallstones was carried out. The dietary evaluation was carried out by the dietary recall method based on a preset questionnaire developed specifically for the present study, keeping in mind the common dietary habits prevailing in this part of the world. Odds ratios (OR) and 95% confidence interval (CI) were calculated for various dietary items. A significant reduction in odds ratio was seen with the consumption of radish (OR 0.4; 95% CI 0.17-0.94), green chilli (OR 0.45; 95% CI 0.21-0.94) and sweet potato (OR 0.33; 95% CI 0.13-0.83) among vegetables, and mango (OR 0.4; 95% CI 0.16-0.99), orange (OR; 0.45; 95% CI 0.22-0.93), melon (OR 0.3; 95% CI 0.14-0.64) and papaya (OR 0.44; 95% 0.2-0.64) among fruits. A reduction in odds was also seen with the consumption of cruciferous vegetables, beans, onion and turnip, however the difference was not statistically significant. On the other hand, an increase in the odds was observed with consumption of capsicum (OR 2.2), beef (OR 2.58), tea (OR 1.98), red chilli (OR 1.29) and mutton (OR 1.2), however the difference was statistically not significant. In conclusion, the results of the present study show a protective effect of vegetables and fruits on gallbladder carcinogenesis, but red meat (beef and mutton) was found to be associated with increased risk of gallbladder cancer.

Coffee intake is associated with lower risk of symptomatic gallstone disease in women

BACKGROUND & AIMS

Metabolic studies have shown that coffee affects several hepatobiliary processes that are involved in cholesterol lithogenesis. We previously showed that coffee drinking was associated with a lower risk of symptomatic gallstone disease in men.

METHODS

We prospectively examined the association between coffee drinking and cholecystectomy, a surrogate of symptomatic gallstone disease, in a cohort of 80,898 women age 34-59 years in 1980 who had no history of gallstone disease. Coffee consumption and cholecystectomy were reported by participants on biennial mailed questionnaires.

RESULTS

During 20 years of follow-up to the year 2000, 7,811 women reported a cholecystectomy. Compared with women who consistently reported consuming no caffeinated coffee, the multivariate relative risks (adjusting for risk factors for gallstone disease) of cholecystectomy comparing increasing categories of consistent intake of caffeinated coffee (0, 1, 2-3, and > or =4 cups/day) were 1.0, 0.91, 0.78, and 0.72 (95% confidence interval comparing extreme categories, 0.62-0.84; P value of test for trend < 0.0001). Caffeine intake from beverages and dietary sources was also inversely associated with risk of cholecystectomy. The multivariate relative risks comparing increasing categories of caffeine intake (< or =25, 26-100, 101-200, 201-400, 401-800, and >800 mg/day) were 1.0, 1.03, 1.01, 0.94, 0.85, and 0.85 (95% confidence interval comparing extreme categories, 0.74-0.96; P value of test for trend < 0.0001). In contrast, decaffeinated coffee was not associated with risk.

CONCLUSIONS

These data suggest that consumption of caffeinated coffee may play a role in the prevention of symptomatic gallstone disease in women.

Prevention of gallstone recurrence by non-steroidal anti-inflammatory drugs

In laboratory animals, non-steroidal anti-inflammatory drugs (NSAIDs) are reported to inhibit diet-induced gallstone formation. To see if these drugs had a similar effect in man, 82 patients who had taken part in a comparison of ursodeoxycholic acid, placebo, and diet for prevention of gallstone recurrence were sent questionnaires about their use of NSAIDs during the period of the trial. 75 replied. After a mean follow-up of 33 (SEM 4) months none of the 12 regular users of NSAIDs had had gallstone recurrences, compared with 20 of the 63 who never or rarely used these drugs (p less than 0.02).

Intraoperative ultrasound and prophylactic ursodiol for gallstone prevention following laparoscopic gastric bypass

BACKGROUND

Previous studies have shown that ursodiol decreases gallstone formation from 32% to 2% following open gastric bypass, but no data exist on laparoscopic Roux-en-Y gastric bypass (LRYGB) using intraoperative ultrasound (IOUS) screening.

METHODS

LRYGB with IOUS were performed on 195 consecutive patients. Patients with gallstones underwent simultaneous cholecystectomy, and patients without gallstones were prescribed ursodiol, 300 mg twice daily, for 6 month. Follow-up survey and ultrasound.

RESULTS

Of 195 patients, 44 (23%) had had a prior cholecystectomy, 21 (11%) underwent a simultaneous cholecystectomy, 129 (66%) had gallbladders left intact, and one (0.5%) false negative IOUS was excluded. Of 69 patients with ultrasound and survey follow-up (mean, 10 months), 19 (28%) developed gallstones seven with symptoms), and 50 (72%) were gallstone free. Forty-one percent of patients were compliant with ursodiol. There was no difference in compliance between patients with and without gallstones. In patients with gallstones, all of the symptomatic patients were noncompliant, whereas none of the compliant patients developed symptoms. Medication side-effects occurred in 17 of 69 patients (25%).

CONCLUSIONS

IOUS during LRYGB efficiently screens for gallstones, and selective cholecystectomy followed by prophylactic ursodiol results in low morbidity. Improvements in compliance may lower the incidence of postoperative gallstone formation.