Effect of a very-high-fiber vegetable, fruit, and nut diet on serum lipids and colonic function

We tested the effects of feeding a diet very high in fiber from fruit and vegetables. The levels fed were those, which had originally inspired the dietary fiber hypothesis related to colon cancer and heart disease prevention and also may have been eaten early in human evolution. Ten healthy volunteers each took 3 metabolic diets of 2 weeks duration. The diets were: high-vegetable, fruit, and nut (very-high-fiber, 55 g/1,000 kcal); starch-based containing cereals and legumes (early agricultural diet); or low-fat (contemporary therapeutic diet). All diets were intended to be weight-maintaining (mean intake, 2,577 kcal/d). Compared with the starch-based and low-fat diets, the high-fiber vegetable diet resulted in the largest reduction in low-density lipoprotein (LDL) cholesterol (33% +/- 4%, P <.001) and the greatest fecal bile acid output (1.13 +/- 0.30 g/d, P =.002), fecal bulk (906 +/- 130 g/d, P <.001), and fecal short-chain fatty acid outputs (78 +/- 13 mmol/d, P <.001). Nevertheless, due to the increase in fecal bulk, the actual concentrations of fecal bile acids were lowest on the vegetable diet (1.2 mg/g wet weight, P =.002). Maximum lipid reductions occurred within 1 week. Urinary mevalonic acid excretion increased (P =.036) on the high-vegetable diet reflecting large fecal steroid losses. We conclude that very high-vegetable fiber intakes reduce risk factors for cardiovascular disease and possibly colon cancer. Vegetable and fruit fibers therefore warrant further detailed investigation.

Dietary fiber and colorectal cancer: what is appropriate advice?

Two recent studies question the role of dietary fiber in the prevention of colorectal cancer. However, the duration of dietary intervention, dose of fiber, and the complexity of polyp formation and transformation to carcinomas make interpretation of such studies difficult. Multiple rationales exist for promoting the consumption of high-fiber, low-fat, fruit- and vegetable-rich diets.

Cardiovascular disease and fiber: is insulin resistance the missing link?

Multiple mechanisms are likely for any effect of fiber on cardiovascular disease risk. One component that is described is the hypocholesterolemic activity of soluble fibers as they bind bile acids. New epidemiologic evidence indicates that fiber's modulation of insulin secretion and resistance deserves additional attention.

Dietary psyllium increases expression of ileal apical sodium-dependent bile acid transporter mRNA coordinately with dose-responsive changes in bile acid metabolism in rats

Psyllium (PSY), a type of dietary fiber containing mainly soluble components, has been shown to decrease serum cholesterol concentrations in several species; however, mechanisms involved are not clearly defined. Four groups of 10 rats were fed semipurified diets containing 10% dietary fiber from cellulose and/or PSY for 21 d. Increasing levels of PSY were fed (0,3.33, 6.67 and 10% PSY) with the remaining 10% made up with cellulose. Liver cholesterol, cholesterol 7alpha-hydroxylase (CYP7A) activity and mRNA, 3-hydroxy-3-methylglutaryl CoA reductase (HMGR) mRNA, ileal apical sodium-dependent bile acid transporter (ASBT) mRNA, fecal bile acids and total steroids, and intestinal bile acid content were measured. All variables responded in a dose-dependent manner to PSY in the diet. Total liver cholesterol content was significantly reduced in all groups fed PSY compared to cellulose-fed controls [138(a), 105(b), 105(b) and 93(c) micromol (SEM = 4.2) for 0, 3.33, 6.67 and 10% PSY, respectively]. Activity of CYP7A was significantly greater in all groups fed PSY compared to the cellulose-fed controls [6.36(c), 16.92(b), 15.28(b) and 20.37(a) pmol x min(-1) x mg protein(-1) (SEM = 3.19) for 0, 3.33, 6.67 and 10% PSY, respectively]. These differences in CYP7A activity were similar to differences in CYP7A, HMGR and ASBT mRNA levels. Fecal bile acid and total steroid excretion as well as total intestinal bile acids were significantly greater in rats fed PSY-containing diets compared to 0% PSY-fed rats. These results suggest that the reduction in liver cholesterol involves modulating the size and composition of the bile acid pool via regulation of ileal ASBT, CYP7A and HMGR mRNA levels.

Effect of soluble and insoluble fiber diets on serum prostate specific antigen in men

PURPOSE

We assess whether high fiber diets influence serum prostate specific antigen (PSA) related to effects on serum sex hormone levels and fecal steroid excretion.

MATERIALS AND METHODS

A randomized crossover controlled trial was performed on 14 healthy men with hyperlipidemia on 2 metabolic diets 4 months in duration with each containing foods high in soluble or insoluble fiber and approximately 25 to 30 gm. dietary fiber per 1,000 kilocalories. Serum PSA, free testosterone and estradiol, and fecal bile acid and neutral sterol excretion were evaluated.

RESULTS

Mean serum PSA was lower with the soluble than the insoluble fiber diet (0.07+/-0.03 ng./ml., p = 0.035). No treatment difference was seen in free testosterone or estradiol, although the latter decreased significantly with the insoluble fiber diet (9+/-3 pmol./l., p = 0.004). After 16 weeks total fecal bile acid output was greater with the soluble (341+/-56 mg. daily) compared to the insoluble (203+/-35, p = 0.001) fiber diet but no differences were seen in fecal neutral sterol elimination. The treatment difference in fecal lithocholic acid output related to the difference in serum PSA (r = 0.57, p = 0.035).

CONCLUSIONS

A small but statistically significantly lower serum PSA was seen in healthy men consuming soluble fiber, which was not related to changes in serum sex hormones but was related to the increased lithocholic acid output as a possible marker of increased fecal steroid elimination. The effect of soluble fiber on prostatic disease may warrant further investigation.

Effect of soluble and insoluble fiber diets on serum prostate specific antigen in men

PURPOSE

We assess whether high fiber diets influence serum prostate specific antigen (PSA) related to effects on serum sex hormone levels and fecal steroid excretion.

MATERIALS AND METHODS

A randomized crossover controlled trial was performed on 14 healthy men with hyperlipidemia on 2 metabolic diets 4 months in duration with each containing foods high in soluble or insoluble fiber and approximately 25 to 30 gm. dietary fiber per 1,000 kilocalories. Serum PSA, free testosterone and estradiol, and fecal bile acid and neutral sterol excretion were evaluated.

RESULTS

Mean serum PSA was lower with the soluble than the insoluble fiber diet (0.07+/-0.03 ng./ml., p = 0.035). No treatment difference was seen in free testosterone or estradiol, although the latter decreased significantly with the insoluble fiber diet (9+/-3 pmol./l., p = 0.004). After 16 weeks total fecal bile acid output was greater with the soluble (341+/-56 mg. daily) compared to the insoluble (203+/-35, p = 0.001) fiber diet but no differences were seen in fecal neutral sterol elimination. The treatment difference in fecal lithocholic acid output related to the difference in serum PSA (r = 0.57, p = 0.035).

CONCLUSIONS

A small but statistically significantly lower serum PSA was seen in healthy men consuming soluble fiber, which was not related to changes in serum sex hormones but was related to the increased lithocholic acid output as a possible marker of increased fecal steroid elimination. The effect of soluble fiber on prostatic disease may warrant further investigation.

Combined effect of vegetable protein (soy) and soluble fiber added to a standard cholesterol-lowering diet

Dietary treatment of hyperlipidemia focuses on reducing saturated fat and dietary cholesterol. Other aspects of diet are not emphasized at present, despite growing evidence that a number of plant components decrease serum cholesterol. We therefore determined whether a combination of two plant components, vegetable protein and soluble fiber, further reduce serum lipids when incorporated into the currently advocated low-saturated-fat diet. Thirty-one hyperlipidemic men and women ate two 1-month low-fat (<7% of total energy from saturated fat), low-cholesterol (<80 mg cholesterol/d) metabolic diets in a randomized crossover study. The major differences between test and control diets were an increased amount of vegetable protein (93% v 23% of total protein), of which 33 g/d was soy, and a doubling of soluble fiber. Fasting blood samples were obtained at the start and end of each phase. On the last 3 days of each phase, fecal collections were obtained. Compared with the low-fat control diet, the test diet decreased total cholesterol (6.2% +/- 1.2%, P < .001), low-density lipoprotein (LDL) cholesterol (6.7% +/- 1.7%, P < .001), apolipoprotein B (8.2% +/- 1.2%, P < .001), and the ratios of LDL to high-density lipoprotein (HDL) cholesterol (6.3% +/- 2.0%, P = .004) and apolipoprotein B to A-I (5.4% +/- 1.5%, P = .001). A combination of vegetable protein and soluble fiber significantly improved the lipid-lowering effect of a low-saturated-fat diet. The results support expanding the current dietary advice to include increased vegetable protein and soluble fiber intake so that the gap in effectiveness between a good diet and drug therapy is reduced.

Select 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitors vary in their ability to reduce egg yolk cholesterol levels in laying hens through alteration of hepatic cholesterol biosynthesis and plasma VLDL composition

The inability to markedly attenuate cholesterol levels in chicken eggs has led to speculation that cholesterol is essential for yolk formation and that egg production would cease when yolk cholesterol deposition was inadequate for embryonic survival. However, this critical level hypothesis remains unproven. Here, we determine the relative responsiveness of laying hens to three select inhibitors of 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGR), the rate-limiting enzyme of cholesterol biosynthesis. A control diet, either alone or supplemented with one of two dietary levels (0.03 or 0.06%) of atorvastatin, lovastatin, or simvastatin, was fed to White Leghorn hens for 5 wk. Liver cholesterol concentrations (mg/g tissue) were decreased (P </= 0.05) by each HMGR inhibitor; however, total liver cholesterol (mg) did not differ among treatments. Microsomal hepatic HMGR activities were increased one- to twofold in all HMGR inhibitor-treated groups, while HMGR mRNA levels were unaffected. Diameters of plasma VLDL particles, the main cholesterol-carrying yolk precursor macromolecules, were reduced (P </= 0.05) only in hens fed 0.06% atorvastatin, and the particles contained 38% less total cholesterol (P </= 0.05) than controls. Plasma total cholesterol concentrations were lowered (P </= 0.05) by both doses of atorvastatin (-56, -63%) and simvastatin (-36,-45%). Egg cholesterol contents were maximally reduced by 46% (P </= 0.05), 7% (P > 0.05), and 22% (P </= 0.05) in hens fed the 0.06% level of atorvastatin, lovastatin, and simvastatin, respectively, while overall egg production [-19% (P </= 0.05), +4% (P > 0.05), and -3% (P > 0.05)], was much less affected. We concluded that cholesterol per se may not be an obligatory component for yolk formation in chickens and, as such, may be amenable to further pharmacological manipulation

Increasing amounts of dietary fiber provided by foods normalizes physiologic response of the large bowel without altering calcium balance or fecal steroid excretion

Nine healthy, young men consumed constant diets to determine selected large-bowel, serum cholesterol and triacylglycerol, and calcium balance responses to 3 amounts of fiber provided by a mixture of fruit, vegetables, and grains. The diets, each consumed for 1 mo, contained 16, 30, and 42 g total fiber/d, of which 2.9, 4.8, and 7.7 g, respectively, was soluble. Mean daily wet and dry stool weights increased with each fiber addition. The first fiber addition increased defecation frequency and decreased fecal pH, bile acid concentration, and neutral steroid concentration; the second addition had no further effect. Mean weight of each defecation and stool moisture did not increase and serum cholesterol and triacylglycerol concentrations, calcium balance, and gastrointestinal transit time did not decrease as fiber intake increased. We conclude that 1) fiber provided by a mixed-food diet increases stool weight as effectively as does wheat or oat bran; 2) even high amounts of dietary fiber do not change transit time or defecation frequency if they are already approximately 1 and 2-3 d, respectively; 3) food patterns consistent with the food pyramid and incorporating legumes and whole grains are necessary to achieve recommended fiber intakes of 20-35 g/d, even if energy intake is > 12.55 MJ (3000 kcal); 4) soluble fiber provided by a mixture of whole foods has no effect on serum cholesterol concentrations or output of fecal bile acids; and 5) mixed-food fiber has little effect on calcium balance when calcium intakes are high (> or = 1.5 g/d).

Dietary psyllium increases fecal bile acid excretion, total steroid excretion and bile acid biosynthesis in rats

Psyllium, a source of dietary fiber rich in soluble components results in lower serum cholesterol concentration in several species. Suggested mechanisms for the hypocholesterolemic effect include a greater excretion of fecal bile acids and total steroids, and up-regulation of bile acid biosynthesis. The activity of cholesterol 7alpha-hydroxylase (7alphaOHase), the rate limiting enzyme in bile acid biosynthesis, is higher in rats fed 5% psyllium. Whether this higher activity corresponds to an increase in mRNA levels has not been determined. Four groups of 10 rats were fed a semipurified diet containing 5% cellulose (CEL; control), 5% cellulose plus 1% cholic acid (CCA), 5% cellulose plus 2% cholestyramine (CHY) or 5% psyllium hydrocolloid (PSY) for 3 wk. Liver cholesterol concentration, fecal bile acid and total steroid excretion, 7alphaOHase activity and 7alphaOHase mRNA levels were measured. Liver cholesterol content in rats fed CCA was significantly higher than in all other groups. Rats fed CHY and PSY had significantly lower liver cholesterol content than those fed CEL. Total fecal steroid and bile acid excretions were significantly greater in rats fed CCA, CHY and PSY than in those fed CEL. Activities and mRNA levels of 7alphaOHase in rats fed CHY and PSY were significantly higher than in rats fed CEL or CCA. These data indicate that feeding psyllium to rats increases fecal bile acid and total steroid excretion as well as 7alphaOHase activity and 7alphaOHase mRNA levels.

Intestinal fatty acid-binding protein variation associated with variation in the response of plasma lipoproteins to dietary fibre

Increased dietary fibre intake is a component of prudent dietary advice, although the mechanism of its beneficial effect is unclear. Furthermore, plasma lipoprotein response to dietary fibre seems to vary both between individuals and according to the type of fibre consumed. Two common genetic variants, A54 and T54, of the intestinal fatty acid-binding protein gene (FABP2) have different in vitro binding affinities for long-chain fatty acids. We have hypothesized that variation in FABP2 would be associated with interindividual variation in the response of plasma lipoproteins to either dietary soluble or insoluble fibre. We studied 43 subjects who participated in a year-long cross-over study of the effect of insoluble and soluble fibre on plasma lipoproteins. We tested for associations between FABP2 genotypes and the response of plasma lipoproteins to dietary fibre. When compared with subjects homozygous for FABP2 A54, we found that subjects with FABP2 T54 had significantly greater decreases in plasma total and low-density lipoprotein (LDL)-cholesterol and apoB during the period when the diet was high in soluble fibre than during the period when the diet was high in insoluble fibre. Furthermore, compared with subjects with the FABP2 A54 allele, subjects with the FABP2 T54 allele had significantly lower secretion of total fecal bile acids, but this did not increase with dietary soluble fibre. Genetic variation in FABP2 may thus contribute to interindividual variation in the response of plasma lipoproteins to different dietary fibres, but the mechanism does not appear to be related to increases in fecal bile acid secretion.

Long-term effect of soluble-fiber foods on postprandial fat metabolism in dyslipidemic subjects with apo E3 and apo E4 genotypes

To determine the long-term effect of soluble fiber on postprandial fat metabolism, we studied 33 dyslipidemic subjects, 16 with apolipoprotein (apo) E3/3 (E3) and 17 with E3/4 or E4/4 (E4) genotypes. They ate preweighed low-fat (20% of energy), high-fiber (> 5.7 g/MJ) diets for two 4-mo periods separated by a 2-mo washout period according to a randomized, crossover design. One diet contained foods rich in insoluble fiber and the other foods rich in soluble fiber. On 1 d during the last 2 wk of each diet, subjects ingested a standard, fiber-free, fatty liquid meal containing retinyl palmitate as a marker of intestinally derived lipoproteins. Plasma samples were obtained at hourly intervals for 10 h. Compared with the insoluble-fiber diet, soluble fiber reduced fasting plasma total cholesterol in both E3 (6.6 +/- 2.1%, P = 0.007)and E4 subjects (5.6 +/- 2.1%, P = 0.017). Soluble fiber increased fecal total bile acid output in both E3 (76 +/- 18%, P < 0.001) and E4 subjects (85 +/- 19%, P < 0.001). The incremental area under the chylomicron triacylglycerol response curve was significantly greater after soluble fiber than after insoluble fiber in E3 (3.56 +/- 0.56 compared with 2.87 +/- 0.38 mmol x h/L, respectively, P = 0.046) but not in E4 subjects (5.19 +/- 0.78 compared with 4.92 +/- 0.81 mmol x h/L). Kinetic analysis suggested an increase in retinyl palmitate absorption in E3 subjects after soluble fiber, but no difference in E4 subjects. These results suggest that a long-term increase in dietary soluble fiber has no effect on postprandial fat metabolism in subjects with an apo E3/4 or E4/4 genotype. However, soluble fiber enhances apparent fat absorption in E3 subjects, which could be due to an increased bile acid pool and increased micelle formation.

Randomized, double-blinded, placebo-controlled study of effect of wheat bran fiber and calcium on fecal bile acids in patients with resected adenomatous colon polyps

BACKGROUND

Ongoing epidemiologic and nutritional studies suggest that colorectal carcinogenesis is consistent with complex interactions between genetic susceptibility and environmental and dietary factors. Among the dietary components found to reduce colon cancer risk are high intakes of dietary fiber and calcium.

PURPOSE

We designed and conducted a randomized, double-blinded, placebo-controlled trial involving supplementation of the customary dietary intake with fiber and calcium and measurements of fecal bile acids to examine the potential mechanisms by which added dietary interventions might reduce colorectal cancer risk.

METHODS

In a randomized, double-blinded, phase II study, we used a factorial design to measure the effects of dietary wheat bran fiber (2.0 or 13.5 g/day) in the form of cereal and supplemental calcium carbonate (250 or 1500 mg/day elemental calcium) taken as a tablet on fecal bile acid concentrations and excretion rates. Measurements were made at base-line randomization (i.e., after a 3-month placebo run-in period using 2.0 g wheat bran fiber plus 250 mg calcium carbonate) and after 3 and 9 months on treatment in a randomly selected 52-patient subsample of the 95 fully assessable study participants who had a history of colon adenoma resection. Concentrations of fecal bile acids, total, primary (i.e., chenodeoxycholic and cholic), and secondary (i.e., deoxycholic, lithocholic, and ursodeoxycholic), were measured in 72-hour stool samples by gas-liquid chromatography. All P values resulted from two-sided tests.

RESULTS

All geometric mean fecal bile acid concentrations and excretion rates were lower at 9 months than at 0 months or 3 months on treatment in the high-dose fiber, high-dose calcium, and high-dose fiber/high-dose calcium treatment groups. The high-dose fiber effect at 9 months of supplementation was statistically significant with respect to virtually all geometric mean fecal bile acid concentrations and excretion rates. For example at 9 months versus 0 months, high-dose fiber supplementation caused a reduction in fecal concentrations of total bile acids (52% reduction; P = .001) and deoxycholic acid (48% reduction; P = .003). High-dose calcium supplementation also had a significant, but lower, effect at 9 months versus 0 months on the geometric mean total bile acid (35% reduction; P = .044) and deoxycholic fecal bile acid (36% reduction; P = .052) concentrations.

CONCLUSIONS

High-dose wheat bran fiber and calcium carbonate supplements given for 9 months are associated with statistically significant reductions in both total and secondary fecal bile acid concentrations and excretion rates in patients with resected colon adenomas. This study supports the hypothesis that one of the important ways in which a high intake of wheat bran fiber and calcium may reduce the risk of colorectal neoplasia and cancer is by reduction of the concentrations of fecal bile acids.

IMPLICATION

Phase III studies of these agents in the prevention of adenoma recurrence are necessary to confirm this hypothesis and have now been initiated at multiple institutions.

Cholesterol 7 alpha-hydroxylase activity is increased by dietary modification with psyllium hydrocolloid, pectin, cholesterol and cholestyramine in rats

Sources of dietary fiber known to alter cholesterol metabolism and/or bile acid pool size were fed to rats, and activity of the rate-limiting step in bile acid synthesis, cholesterol 7 alpha-hydroxylase, was measured. In the first experiment, semipurified diets containing 5% cellulose, psyllium hydrocolloid, pectin or oat bran as dietary fiber sources or 2% cholestyramine were fed to groups of 10 male Wistar rats for 4 wk. In the second experiment, groups of six rats were fed diets containing 5% cellulose, rice bran, oat bran or psyllium with and without 0.25% cholesterol. In the first experiment, the activity of cholesterol 7 alpha-hydroxylase (pmol.min-1.mg protein-1) was highest in the cholestyramine-treated group (95.6 +/- 3.6), followed by groups fed psyllium (35.5 +/- 3.5) or pectin (36.0 +/- 4.5), which exhibited more than twice the enzyme activity of groups fed cellulose (16.9 +/- 1.9) or oat bran (12.3 +/- 2.0). In the second experiment, feeding cholesterol resulted in significantly higher enzyme activity when cellulose (65%), oat bran (118%) and rice bran (60%) were fed, but no difference in activity was observed when cholesterol was added to the psyllium-containing diet. Higher activity of cholesterol 7 alpha-hydroxylase when pectin or psyllium rather than cellulose was fed may explain the almost twofold higher bile acid pool sizes previously reported in response to feeding either of these fibers. These data support the hypothesis that the hypocholesterolemic effect of soluble fibers is modulated through increased synthesis and therefore pool size of bile acids.

Mechanism of serum cholesterol reduction by oat bran

Nine normolipidemic young men consumed a constant diet for 2 mo into which oat bran was incorporated during the second month so that we might test the hypotheses that oats lower serum cholesterol concentrations by decreasing bile acid and fat absorption and increasing bile acid synthesis. Bile acid kinetics were determined by measuring the 13C enrichment of serum cholic and chenodeoxycholic acids. Oat bran consumption decreased serum cholesterol levels (p < 0.01) and cholic acid pool size (p < 0.05). Deoxycholic acid pool size (p < 0.01) and the synthesis and fractional turnover rates of both primary bile acids (p < 0.05) increased. Total bile acid pool size did not change. Fecal excretion of total bile acids, the two secondary bile acids and fat increased significantly. The results demonstrate that oat bran lowers serum cholesterol levels in part by altering bile acid metabolism. In addition, the substantial increase in the proportion of the total bile acid pool that was deoxycholic acid is consistent with the hypothesis that oat bran also decreases cholesterol synthesis.

Dietary psyllium hydrocolloid and pectin increase bile acid pool size and change bile acid composition in rats

Bile acid composition, synthetic rate and pool size were determined in rats fed diets containing 5 g cellulose, 5 g pectin or 5 g psyllium hydrocolloid/100 g diet using the washout technique. Bile acid pool sizes were similar for pectin- and psyllium-fed rats, and both were higher than the pool size for rats fed cellulose (5.48 +/- 1.22, 4.70 +/- 0.71 and 1.77 +/- 0.41 mumol/100 g body wt, respectively). Bile acid secretion rates showed a similar pattern [1730 +/- 496, 1551 +/- 252 and 572 +/- 88 nmol/(h.100 g body wt)], as did basal synthetic rates [129 +/- 25, 126 +/- 42 and 87 +/- 18 pmol/(h.100 g body wt)]. Individual and total bile acid pool sizes were generally higher in animals fed the pectin- or psyllium-supplemented diet compared with rats fed cellulose. Pectin or psyllium consumption resulted in a lower hydrophobicity of the bile acid pool and a lower ratio of circulating 12 alpha-hydroxylated to non-12 alpha-hydroxylated bile acids compared with cellulose consumption. This reduced hydrophobicity has been shown to reduce feedback inhibition of bile acid synthesis and may be responsible for the larger bile acid pool size. Changes in the location of reabsorption of bile acids may also be responsible for changes in the pool size and composition. These changes are characteristic of greater sterol excretion.

Ultracentrifugal and electrophoretic characteristics of the plasma lipoproteins of miniature schnauzer dogs with idiopathic hyperlipoproteinemia

To better characterize the idiopathic hyperlipoproteinemia of Miniature Schnauzer dogs, the plasma lipoproteins of 20 Miniature Schnauzers (MS) and 11 dogs of other breeds (DOB) were evaluated by ultracentrifugation, electrophoresis, and biochemical tests. Seventeen MS were healthy; 3 had diabetes mellitus. Plasma from 6 of 17 healthy and all 3 diabetic MS was visibly lipemic. Lipemia was slight to marked in healthy lipemic MS, and marked in diabetic ones. All DOB had clear plasma; 8 were healthy and 3 had diabetes. All healthy lipemic MS and diabetic lipemic MS had hypertriglyceridemia associated with excess very low density lipoproteins. Chylomicronemia was present in 4 of 6 healthy lipemic MS and all 3 diabetic lipemic MS. Lipoproteins with ultracentrifugal and electrophoretic characteristics of normal low density lipoprotein were lacking in 4 of 6 healthy lipemic MS. The lipoprotein patterns of 4 of 11 healthy nonlipemic MS were characterized by mild hypertriglyceridemia associated with increased very low density lipoproteins and a lack of lipoproteins with characteristics of normal low density lipoproteins. Lipoprotein patterns of diabetic DOB closely resembled those of healthy DOB; those of diabetic lipemic MS resembled those of markedly lipemic healthy lipemic MS. In conclusion, the hyperlipoproteinemia of Miniature Schnauzers is characterized by increased very low density lipoproteins with or without accompanying chylomicronemia; some affected dogs may have decreased low density lipoproteins.

Effects of psyllium hydrophilic mucilloid on LDL-cholesterol and bile acid synthesis in hypercholesterolemic men

The goal of the current study was to determine the mechanism of the hypocholesterolemic effect of psyllium using a randomized, double-blind, crossover design. Twenty males (age 44 +/- 4 yr, weight 79 +/- 10 kg) with moderate hypercholesterolemia (total 265 +/- 17 mg/dl, low density lipoprotein (LDL) 184 +/- 15 mg/dl) were studied at baseline (B) and after randomization to receive a 40-day course of 15 g/day of either psyllium (Ps) or placebo (Pl) (cellulose). After a washout period (11 +/- 2 days), subjects were crossed over to the other fiber treatment for an additional 40 days and restudied. Intestinal cholesterol absorption, cholesterol synthesis in isolated peripheral blood mononuclear cells, bile acid kinetics, gallbladder motility, and intestinal transit were measured at each study period. Psyllium lowered LDL cholesterol (x:184 (B), 169 (Ps), and 179 (Pl) mg/dl; Ps vs. B,Pl: P less than 0.004, P less than 0.02), decreased relative cholesterol absorption (x:51 (B), 45 (Ps), and 49 (Pl) %; Ps vs. B,Pl: P less than 0.03, P less than 0.03), did not alter absolute cholesterol absorption, and increased the fractional turnover of both chenodeoxycholic acid (x:0.176 (B), 0.203 (Ps), and 0.170 (Pl) day-1; Ps vs. B,Pl: P less than 0.0001, P less than 0.01) and cholic acid (x:0.303 (B), 0.411 (Ps), and 0.301 (Pl) d-1; Ps vs. B, Pl: P less than 0.006, P less than 0.002). Bile acid synthesis increased in subjects whose LDL cholesterol was lowered by more than 10% (Ps vs. B: 1304 +/- 489 vs 992 +/- 307 mumol/day, P less than 0.006; Ps vs. PI: 1304 +/- 489 vs. 914 +/- 321 mumol/day, P less than 0.0002). We conclude that psyllium lowers LDL cholesterol primarily via stimulation of bile acid synthesis.

Lymph chylomicron size is modified by fat saturation in rats

Mesenteric lymph chylomicrons were characterized during and after the establishment of steady-state triglyceride transport. Chylomicrons were isolated from lymph at 0, 2, 4, 6, 8 and 12 h after the start of an 8-h infusion of triglyceride emulsion (prepared using either corn or butter oil) at 160 mumol/(kg.h). Lymph flow was not influenced by triglyceride source. Output of triglyceride, measured both in whole lymph and in the chylomicron fraction, was not significantly affected by triglyceride source. Butter oil infusion produced a higher output of chylomicron phospholipid and unesterified cholesterol than was observed in response to corn oil emulsion. Ratios of transported phospholipid to triglyceride for butter oil chylomicrons were higher (1.3- to 1.7-fold) than those for corn oil chylomicrons at every time point examined after the start of lipid infusion. No other compositional differences in chylomicrons due to triglyceride source were observed. These results support the hypothesis that differences in efficiency of absorption and transport between saturated and unsaturated fat are sufficient to explain size differences in secreted chylomicrons in response to corn and butter oil infusions, and suggest that chylomicron number may be influenced by dietary fat saturation.

Lymph chylomicron composition and size are modified by level of intestinally infused cholesterol and triglyceride source in rats

Mesenteric lymph chylomicrons were characterized following acute continuous intestinal infusion of triglyceride emulsions in rats. Emulsions were prepared using corn, olive or butter oils with graded doses of cholesterol (0, 3, 10, 20, 30, 60, 100 mg/g triglyceride) added to each. Chylomicron cholesterol content varied directly with dose of cholesterol infused, ranging from approximately 1.5% (by weight) with no added cholesterol to 5-10% at 100 mg cholesterol/g triglyceride. Minimum effective dose for increasing chylomicron cholesterol content (about twofold) was 20 mg/g triglyceride regardless of the triglyceride source. Esterified cholesterol accounted for most of the increase in chylomicron total cholesterol with corn oil infusion, whereas increases in the unesterified fraction accounted for 10-30% of the increase in total cholesterol during infusion of olive or butter oils. The effect of infused cholesterol on chylomicron lipid composition was dependent on triglyceride source: no effect on phospholipid:triglyceride ratio with corn and butter oils, but increased phospholipid:triglyceride ratio with olive oil at cholesterol doses greater than 20 mg/g triglyceride. Infusion of butter emulsions produced smaller chylomicrons than those produced during infusion of corn or olive oil emulsions.

Bile acid analysis: methods and problems

What is the ideal method for analysis of faecal bile acids? Selection of an ideal system for a specific situation requires consideration of several factors, eg the information sought, availability of equipment and time constraints. Each laboratory will select procedures based on these constraints. A situation in which a large number of subjects are to be screened for total bile acid concentration might suggest use of single-day collections, lyophilization prior to homogenization, extraction using the Evrard and Janssen method and quantification by 3 alpha-hydroxysteroid dehydrogenase. However if the ratio of glycine to taurine conjugates and the daily excretion were of interest, separation of subclasses with Lipidex 1000 followed by both gas chromatography (of free bile acids) and HPLC (of conjugated bile acids) would be selected. There is not a best method for all situations. What does the future hold for improving this methodology in order to improve our ability to use faecal bile acid analysis clinically? The biggest problem facing the application of faecal bile acid analysis to clinical situations in the lack of ability to devise a rapid method (24-48 h) which retains the accuracy of current methods. One promising development is the potential application of immunological methods to faecal bile acids. These detection methods have been applied primarily to serum to date but if extraction and/or purification methods could be coupled with this method of quantification, a clinically acceptable method may result.(ABSTRACT TRUNCATED AT 250 WORDS)

Studies of women eating diets with different fatty acid composition. I. Plasma lipoproteins and steroid excretion

Moderate changes in dietary fat composition have been recommended to improve plasma cholesterol status. Such changes have not been studied extensively in women. This research evaluates plasma lipoprotein and steroid excretion changes in young women who consumed a diet similar to US average consumption in 1974 [40 en% fat, polyunsaturated (P) to saturated fatty acid (S) ratio, P/S = 0.3, US74] or a diet modified to contain 30 en% fat, P/S = 1.0 (MOD). Following a preexperimental period of self-selected diets, young women were fed the diets for 28-day periods in a crossover design with 10 women at the University of Nebraska, Lincoln, and 10 at Iowa State University, Ames. Plasma lipoproteins and steroid excretion were quantitated and the compositions determined. Data were analyzed for race (five Chinese, 14 Caucasians) and for diet carryover effects, as well as for primary diet effects. In the Chinese women, the US74 diet raised total and very-low-density lipoprotein (VLDL) cholesterol compared to prior self-selected or modified diets; in the Caucasian women the MOD diet lowered total, low-density lipoprotein (LDL), and VLDL cholesterol. The diet carryover was evident in total high-density lipoprotein (HDL) and HDL3 cholesterol. Total HDL and HDL3 cholesterol in response to the US74 diet were unchanged from the MOD diet when the US74 diet followed the MOD diet, but were lower than modified when the US74 diet followed self-selected diets. The US74 diet resulted in greater neutral sterol excretion than the MOD diet; this response was more marked in the self-selected, US74, MOD sequence than in the self-selected, MOD, US74 sequence.(ABSTRACT TRUNCATED AT 250 WORDS)

Assessment of endogenous opioid mediation in stress-induced hypercholesterolemia in the rat

Stressful stimuli are known to elevate total plasma cholesterol levels and activate endogenous opioid systems. In cholesterol-cholic, acid-fed female rats, a 5-day unpredictable immobilization stress paradigm increased levels of low plus very low density lipoprotein cholesterol and reduced levels of high density lipoprotein cholesterol. Pretreatment with the opiate antagonist, naltrexone (1.0 mg/kg, sc) prevented the stress-induced changes. Five-day morphine pellet implants (75 mg) duplicated the cholesterol alterations seen in immobilized rats. In addition, plasma triglyceride levels were elevated in morphine pelleted rats, but hepatic and aortic cholesterol levels were unchanged. Unchanged plasma sorbitol dehydrogenase activity and hepatic triglyceride levels indicated that both regimens were not hepatotoxic. These findings support the possible role for endogenous opioid systems in stress-induced hypercholesterolemia.

Stress- and morphine-induced elevations of plasma and tissue cholesterol in mice: reversal by naltrexone

Our earlier studies indicated that stress-induced facilitation of gallstone formation could be prevented by the opiate antagonist naltrexone. In view of the possible link between gallstone formation and atherosclerosis, the present study examined the possibility that endogenous opioids might also mediate stress-induced hypercholesterolemia. A 28-day immobilization stress schedule was used to induce increases in plasma, aortic and liver cholesterol of mice maintained on a high cholesterol diet. These stress-induced increases in plasma, hepatic and aortic cholesterol were reversed by pretreatment with the opiate antagonist, naltrexone (1 mg/kg). Exposure of mice to morphine (0.1% in the drinking water for 28 days) resulted in elevations of plasma, liver, and aortic cholesterol levels, similar to those observed following immobilization. In contrast, chronic exposure to the peripherally restricted opiate agonist, loperamide (0.1% in the drinking water for 28 days), was ineffective. The antagonism by naltrexone and duplication by morphine but not loperamide suggest that stress-induced hypercholesterolemia may require the activation of central endogenous opioid systems.

Dietary fiber supplementation and fecal bile acids, neutral steroids and divalent cations in rats

Young adult rats were fed ad libitum for 4 wk on defined diets containing either no fiber, 10% levels of insoluble fiber sources [cellulose, wheat bran, alfalfa, mixed fibers (Fibyrax)], 5% levels of soluble fiber sources [pectin, guar gum, psyllium (Metamucil)] or 2% cholestyramine (Questran), a bile acid sequestrant. Fecal samples were obtained from paired rats over a 3-d period, were analyzed for neutral and acidic steroid levels and compositions and, together with the food, were assayed for divalent cations (Ca2+, Mg2+, Fe2+ and Zn2+). Animals in all groups were in balance for divalent cations, and there appeared to be no relationship between the extent of cation balance and the type of fiber fed. All insoluble fiber diets and the guar gum and psyllium diets resulted in significantly higher daily fecal mass and, in general, resulted in significant dilution of total fecal steroids. With the insoluble fibers, there was a general dilution of fecal neutral steroids, which was not apparent with the soluble fibers or cholestyramine. In addition, except for the pectin- and mixed fiber-containing diets, there was reduced bacterial conversion of the primary bile acids to secondary bile acids or metabolites.

Short-term changes in hepatic HMG-CoA reductase in rats fed diets containing cholesterol or oat bran

In vivo regulation of hepatic HMG-CoA reductase (HMGR) (mevalonate:NADP+ oxidoreductase [acylating CoA]; EC 1.1.1.34] by phosphorylation/dephosphorylation has not been demonstrated. Rats were meal-fed semipurified diets; effects of inclusion of cholesterol (2%) or oat bran (15%) in a single meal on expressed (phosphorylated) and total (dephosphorylated) activities of HMGR were measured from 15 min to 4 hr after presentation of the meal. Expressed activity was not significantly altered in response to the control diet during the time periods examined, while total HMGR activity declined by 15 min and increased through 4 hr to an activity about 1.5 times control levels. Addition of cholesterol resulted in little change in expressed activity but a greater and more sustained reduction in total activity. Oat bran caused reductions in both total and expressed activities, which were maintained through 4 hr. Total HMGR activity was best correlated with apparent demand for cholesterol synthesis.

Morphine-induced alterations in plasma and tissue cholesterol levels

In rats fed a cholesterol-cholic acid supplemented diet, implantation of a 75 mg morphine pellet elevated total plasma cholesterol, raised low density lipoprotein (LDL) plus very low density lipoprotein (VLDL) cholesterol, and lowered high density lipoprotein (HDL) cholesterol levels. The resultant increase of the atherogenic index was accompanied by enhanced aortic cholesterol deposition. These alterations were prevented by daily administration of naltrexone (1.0 mg/kg, sc), and were not associated with hyperphagic or hepatotoxic actions of morphine. An increase in total plasma cholesterol and in LDL plus VLDL cholesterol was also observed in morphine pelleted rats maintained on a normal diet. The possible implications of opiate-induced hypercholesterolemia are discussed.

Fatty acid composition of mature human milk of Egyptian and American women

Fatty acid composition of mature human milk of rural Egyptian and American women was determined by gas-liquid chromatography. Milk of Egyptian women contained significantly higher percentages of capric, lauric, myristic, linoleic and arachidonic acids, saturated fatty acids (SFA), and polyunsaturated fatty acids (PUFA). Conversely, milk of American women contained higher percentages of stearic and oleic acids, total unsaturated fatty acids, and monounsaturated fatty acids. The PUFA:SFA ratio in Egyptian samples was 0.54 +/- 0.18 compared to 0.47 +/- 0.22 in American samples. Increased percentages of medium-chain SFA in Egyptian milk suggested increased mammary gland lipid synthesis. Analysis of Egyptian diets indicated high-carbohydrate and low-fat intakes may have resulted in limited availability and incorporation of dietary fatty acids into milk triglycerides. Thus, increased percentages of medium-chain SFA observed in Egyptian milk may reflect mammary gland synthesis in an attempt to maintain lipid concentrations in milk.

Effect of increasing levels of hard wheat fiber on fecal weight, minerals and steroids and gastrointestinal transit time in healthy young women

Hard red wheat bran (HRWB) baked in a yeast-leavened bread was fed to 36 healthy young college women consuming a basal diet of traditional foods, which contained 15 +/- 3 g/d dietary fiber (DF). Three levels of HRWB were added supplying, respectively, 5.7, 17.1 and 28.5 g/d DF; an additional treatment group did not receive any HRWB. Fecal collections were carried out in the last 5 d of treatment. Fecal wet weight, fecal dry weight and fecal ash increased significantly for each increase in HRWB (P less than 0.05). Fecal dry matter percent changed significantly only at the highest level of HRWB (P less than 0.05). After accounting for the minerals in the HRWB, there was an increased fecal loss of Ca, but not of Zn, Cu, Fe or Mg compared to the women fed no HRWB. HRWB at a level of 17.2 g/d induced faster transit times (TT) than no HRWB and 66 g/d HRWB induced faster TT than either 17.2 or 39.6 g/d HRWB (P less than 0.05). Total daily fecal steroids were not altered by changes in HRWB. Daily total bile acid excretion increased significantly (P less than 0.05) at the two higher levels of HRWB due primarily to higher excretion of chenodeoxycholic acid.

An improved assay for cholesterol 7 alpha-hydroxylase activity using phospholipid liposome solubilized substrate

A persistent problem in measurement of cholesterol 7 alpha-hydroxylase (7 alpha-OHase) activity by isotope incorporation has been solubilization of cholesterol substrate. Solubilization with Tween 20, for example, resulted in a 75% reduction in 7 alpha-OHase activity after a 60 min incubation of substrate with microsomes. Incorporation of cholesterol substrate into small, unilamellar phospholipid vesicles (liposomes) prevented this effect, resulting in a 50% increase in activity over the same 60 min incubation at optimal concentrations. Using cholesterol in liposomes as substrate, standard assay conditions were determined to be: preparation of liposomes with 180 microM cholesterol substrate and 0.5 mg phospholipid/assay; incubation of these liposomes with 0.5 mg microsomal protein at 37 C for 60 min; addition of a NADPH generating system to start the reaction, and incubation at 37 C for 30 min before stopping the reaction and determining the amount of 7 alpha-hydroxycholesterol formed. In addition to preventing the detergent-related inhibition of the enzyme, liposome-solubilized substrate also reduced the variation among replicates from a coefficient of 45% with Tween 20 to 4.2% with phospholipid. This method provides a sensitive and reliable alternative to methods which require more sophisticated equipment and allows total control of substrate concentration in a form readily accessible to the enzyme.

Effect of type of diet and feeding status on modulation of hepatic HMG-CoA reductase in rats

The effect of diet type and feeding status on hepatic HMG-CoA reductase (HMGR) [mevalonate: NADP+ oxidoreductase (acylating CoA); EC 1.1.1.34] was studied in rats. Animals fed a ground, commercial, stock diet exhibited higher expressed and total activities of HMGR in the fed state than animals fed a semi-purified diet. The differences did not appear in meal-trained animals when measured before the onset of the meal after a 22-hr fast. When expressed activity was taken as a per cent of total activity, fed animals from both diet groups used about 10% of their available activity. When animals on commercial diets were fasted, 20% of the activity was expressed. Fasted animals on the semi-purified diet also increased the per cent of expressed reductase activity, but this increase was not as great (13.3%). These data suggest that, in the rat, regulation of cholesterol synthesis in response to decreased total HMGR during fasting and increased levels after a meal results from alterations in the percentage of enzyme which is expressed. The semi-purified diet used here resulted in consistently lower levels of HMG-CoA reductase activity than the commercial diet regardless of feeding pattern.

Interactions of alfalfa plant and sprout saponins with cholesterol in vitro and in cholesterol-fed rats

The in vitro interactions of saponins from alfalfa plant and alfalfa sprouts with cholesterol and the effects of alfalfa plant and sprout and saponin-free alfalfa plant on diet-induced liver cholesterol accumulation, bile acid excretion, and jejunal and colonic morphology were examined. Cholesterol-saponin interactions have been suggested as mechanisms for the observed hypocholesterolemic effects of alfalfa as well as the changes in intestinal morphology. Alfalfa plant saponins bound significant quantities of cholesterol both from ethanol solution and from micellar suspension. Alfalfa sprout saponins interacted with cholesterol to a lesser but significant extent. Sprout saponins also inhibited growth of Trichoderma viride significantly, another measure of saponin-cholesterol interaction. Bile acid adsorption was greatest for alfalfa plant and was not reduced by removal of saponins from the plant material. The ability of alfalfa to reduce liver cholesterol accumulation in cholesterol-fed rats was enhanced by removal of saponins and alfalfa sprouts did not prevent accumulation. Removal of saponins from alfalfa reduced the changes in intestinal morphology previously reported, but interaction with membrane cholesterol did not appear to be the cause of this effect of saponins. Saponin-cholesterol interaction is an important part of the hypocholesterolemic action of alfalfa but interaction of bile acids with other components of alfalfa may be of equal importance.

Alteration of regression of cholesterol accumulation in rats by dietary pectin

Male, Wistar rats (50-74 g) were given a semi-purified diet containing cholesterol (10 g/kg diet) for 4 weeks, groups of control and experimental animals killed, and the remainder of the cholesterol-fed animals given either a semi-purified cholesterol-free diet without a fibre source or a similar diet with pectin (50 g/kg diet) for 8 weeks. Animals were killed at 2-week intervals and serum and liver cholesterol and triglycerides, faecal neutral steroids and acidic steroids measured. Animals given pectin had significantly lower serum cholesterol levels than animals given the basal diet after 4 and 6 weeks. Both experimental groups efficiently decreased their liver cholesterol levels during regression. Bile acid excretion was elevated in both groups, especially in rats receiving pectin, but neutral steroid excretion was unchanged. The increase in bile acid excretion was primarily in the form of chenodeoxycholic acid and its metabolites. This increased bile acid excretion is postulated to result from stimulation of the normal mechanism for increased steroid excretion in the rat, i.e. a change in the value of cholic: chenodeoxycholic acid or from a mechanism not yet elucidated.

Dietary carbohydrate and atherosclerosis

Epidemiologic evidence indicated a relationship between refined sugar intake and increased serum cholesterol levels and atherosclerotic heart disease, which resulted in a series of human and animal experiments examining this relationship. Sucrose and fructose were found to be more atherogenic in rabbits and baboons when fed as part of a semipurified diet. However, serum lipid levels were not always elevated when more severe atherosclerosis was present. Human studies generally observed increases in serum triglycerides and, less consistently, serum cholesterol in response to substitution of sucrose for starch or glucose. These differences in lipid levels and experimental atherosclerosis are thought to arise from 1) increased endogenous triglyceride synthesis, present in serum as very low-density lipoproteins; 2) impaired clearance of these lipoproteins; 3) slowed turnover of cholesterol into bile acids; and 4) possible changes in aortic connective tissue metabolism.

Experimental atherosclerosis in rabbits fed cholesterol-free diets. Part 9. Beef protein and textured vegetable protein

Rabbits were fed a semipurified diet containing 40% sucrose, 25% protein, 15% fiber and 14% tallow. The proteins fed were beef (B), textured vegetable protein (TVP) and casein (C). One diet contained beef-TVP (1 : 1) and in another a soy carbohydrate fraction, spent flakes, was added to the diet; it provided 2.2% protein and 10.5% fiber. TVP provided 6.4% soluble carbohydrate and 10.5% fiber. The diets were fed from 8 months. Diets containing beef protein or casein gave significantly higher serum cholesterol levels and atherosclerosis and significantly lower serum HDL-cholesterol than did the other 3 diets. The beef-TVP (1 : 1) diet gave low serum cholesterol (67% below beef) levels and atherosclerosis (47% below beef). This effect is probably due to the protein. The diet containing spent flakes gave low serum cholesterol levels (44% below beef) and atherosclerosis (45% below beef). This effect is attributed to the different fiber. The lowest serum cholesterol levels and least severe atherosclerosis were observed in the rabbits fed TVP.

Age-strain interrelations in lipid metabolism of rats

Various aspects of lipid metabolism were compared in Fisher 344 (F) and Sprague-Dawley (SD) rats aged 2, 6, 12, 18 and 24 months. The analyses included free and total cholesterol of serum and liver, LCAT, hepatic HMG-CoA reductase, cholesterol 7 alpha-hydroxylase, fatty acid synthetase, acetyl CoA carboxylase and cholesterol synthesis from acetate or mevalonate. The body weight of SD rats increases with age whereas that of F rats plateaus at 9-12 months. Liver and aorta cholesterol levels were comparable for the 2 strains. Serum cholesterol varied but was usually lower in F rats. HMG-CoA reductase and cholesterol 7 alpha-hydroxylase activities were not significantly different. Cholesterol synthesis from acetate was significantly higher only in 2-month-old F rats; synthesis from mevalonate was similar at each level. Acetyl CoA carboxylase and fatty acid synthetase activity were generally higher in F rats at every age level. The major difference between F and SD rats is in their pattern of weight gain with age. Differences in lipid metabolism are most marked between the young (2-month) rats.

Effect of chronic intake of dietary fibers on the ultrastructural topography of rat jejunum and colon: a scanning electron microscopy study

This report is an attempt to quantitate the observable topographical characteristics of small and large intestine after a specific dietary regimen under well-defined states of lipid absorption and metabolism. Alfalfa, white wheat bran, cellulose, and pectin were fed for 6 wk at a level of 15 g/100 g diet to four groups of rats (12 rats per dietary group). A 5th control group was maintained on Purina Rat Chow. Three animals from each group were blind-coded for morphological assessment. After anesthesia, the jejunum and mid-colon were removed and processed for scanning electron microscopy. Beginning with the mildest mucosal surface changes, the observed order in terms of increasing severity is bran less than cellulose less than pectin less than alfalfa. Our observations suggest that altered rates of cell loss in intestinal tract cytokinetics may be occurring with particular feeding patterns and should be considered as a possible mechanism in the nutritional consequences of dietary fiber intake.

Effect of bile salt-binding resins on the morphology of rat jejunum and colon. A scanning electron microscopy study

One mechanism suggested to account for the hypocholesteremic effect of dietary fibers is their ability to sequester bile salts. Since bile salts have been found to alter intestinal structure, the morphological effects of several commonly used, xenobiotic, bile salt-binding agents was investigated. Wistar rats were fed a purified stock diet, ad libitum, for 6 weeks containing either 2% cholestyramine, 2% colestipol, or 2% DEAE-Sephadex. The bile salt-binding capacity of these substances was tested in vitro using taurocholate and glycocholate. The effect of in vivo feeding of the resins was to evoke ultrastructural topographical deviations from control appearance in both jejunal and colonic mucosae. Colonic cell injury was more severe than that observed in the jejunum of both colestipol- and DEAE-Sephadex-fed animals while the reverse was true for the rats fed cholestyramine. The degree of distortion in each condition was positively correlated with the extent of bile salt-binding capability in vitro. The rank order of both effects in terms of increasing severity was DEAE-Sephadex less than colestipol less than cholestyramine.