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Original Article

Effect on Blood Lipids of Very High Intakes of Fiber in Diets Low in Saturated Fat and Cholesterol

List of authors.
  • David Jenkins,
  • Thomas Wolever,
  • A. Venketeshwer Rao,
  • Robert A. Hegele,
  • Steven J. Mitchell,
  • Thomas Ransom,
  • Dana L. Boctor,
  • Peter J. Spadafora,
  • Alexandra L. Jenkins,
  • Christine Mehling,
  • Lisa Katzman Relle,
  • Philip W. Connelly,
  • Jon A. Story,
  • Emily J. Furumoto,
  • Paul Corey,
  • and Pierre Wursch

Abstract

Background

It is known that soluble fiber in the diet can lower blood lipid levels. It is less certain, however, that eating foods with soluble fiber will further lower blood lipids when the intake of saturated fat and cholesterol has already been reduced to very low levels. Furthermore, the mechanism of the lipid-lowering effect of fiber has not been elucidated.

Methods

To address these questions, we studied 43 volunteers with hyperlipidemia in a crossover study involving two four-month dietary periods. The two metabolic diets contained foods high in either soluble or insoluble fiber and were separated by a two-month National Cholesterol Education Program Step 2 diet. The metabolic diets were low in saturated fat (<4 percent of total calories) and cholesterol (<25 mg per 1000 kcal), high in carbohydrate ( ≥ 60 percent of total calories), and very high in fiber (>24 g per 1000 kcal).

Results

Blood lipids fell to their lowest levels by week 4 of both study diets. When the soluble-fiber period was compared with the insoluble-fiber period, the subjects' total, low-density lipoprotein (LDL), and high-density lipoprotein (HDL) cholesterol levels were found to be lower by a mean (±SE) of 4.9 ±0.9 percent (P<0.001), 4.8 ±1.3 percent (P<0.001), and 3.4 ±1.3 percent (P = 0.014), respectively. In contrast, the ratio of total to HDL cholesterol was not significantly different during the two dietary periods. The loss of fecal bile acids was 83 ±14 percent greater during the soluble-fiber period than during the insoluble-fiber period (P<0.001) and was related to the differences in total and LDL cholesterol and apolipoprotein B levels (r = 0.42, P = 0.005; r = 0.49, P<0.001; and r = 0.33, P = 0.035, respectively). The difference in serum cholesterol levels between the two dietary periods was greater among the men (7.5 ±1.2 percent, P<0.001) than among the women (3.4 ±1.2 percent, P = 0.008).

Conclusions

Very high intakes of foods rich in soluble fiber lower blood cholesterol levels even when the main dietary modifiers of blood lipids -- namely, saturated fat and cholesterol -- are greatly reduced.

Introduction

To reduce blood cholesterol levels and prevent coronary heart disease, major agencies recommend reduced consumption of saturated fat and cholesterol1,2 and increased intake of carbohydrate foods high in fiber, especially soluble fiber. One benefit of eating high-carbohydrate foods is that they displace saturated fat and cholesterol from the diet3,4. Indeed, it has been doubted whether a high intake of fiber can further reduce plasma lipids after marked reductions in dietary saturated fat and cholesterol have been achieved3.

To address this issue and the possible mechanisms involved, we fed volunteers with hyperlipidemia foods high in soluble fiber that had been reported to lower serum lipid levels,5-9 as part of metabolic diets that were high in carbohydrate and very low in saturated fat and cholesterol. The control diet was high in wheat fiber, an insoluble fiber that is generally regarded as lipid neutral9.

Methods

We studied 43 healthy subjects (15 men and 28 postmenopausal women). The subjects were predominantly of normal weight (mean [±SE] percent of ideal body weight, 107 ±4; range, 95 to 172), and their mean age was 58 ±3 years (range, 29 to 70). They had previously been found to have mild-to-severe hyperlipidemia. After following a National Cholesterol Education Program Step 2 diet1 for at least two months, all but 2 subjects had plasma lipid levels above the desirable range (22 had low-density lipoprotein [LDL] cholesterol levels >160 mg per deciliter [4.1 mmol per liter]; 5 had triglyceride levels >200 mg per deciliter [2.3 mmol per liter]; and 14 had both LDL cholesterol levels >160 mg per deciliter and triglyceride levels >200 mg per deciliter)1. The subjects were randomly assigned to two metabolically controlled diets, each for four months. One diet was high in soluble fiber, and the other high in insoluble fiber. No attempt was made to blind the subjects or study personnel to the dietary assignments. The metabolic diets were separated by a two-month return to an ad libitum Step 2 diet (total fat, <30 percent of calories; saturated fat, <7 percent of calories; and cholesterol, <200 mg daily). None of the subjects had clinical or biochemical evidence of diabetes, hepatic disease, or renal disease, and none were taking hypolipidemic agents. Three women were taking estrogen-replacement therapy, one man and one woman were taking levothyroxine, and one man and two women were taking beta-blocking agents. Dosage levels were the same for both study periods, except that one subject took a low dose of propranolol during the soluble-fiber period only. All the subjects were asked to keep their level of physical activity constant.

Before the study began and at weeks 2, 4, 8, 12, 14, and 16 of each metabolic diet, blood samples were taken for lipid analysis while the subjects were fasting. Buffy coat was obtained to determine the apolipoprotein E genotype10. During the last two weeks of each dietary period, the subjects spent two separate days in the clinical nutrition center. On one, a day profile was determined. The subjects were given their usual breakfast and, four hours later, their lunch. Blood samples were obtained at the outset and 30, 60, 120, and 240 minutes after each meal for the measurement of lipids, glucose, insulin, metabolites, and short-chain fatty acids. Results are reported for the first 11 patients. On a separate day, usually the last day of each dietary period, a fat-tolerance test was conducted involving the consumption of a “milkshake” containing 5 ml of water, 0.5 g of corn oil, 1.38 g of skim-milk powder, and 0.5 g of glucose per kilogram of body weight and a total of 50,000 units of vitamin A palmitate. Blood was obtained at the outset and after 30, 60, 180, 240, and 300 minutes for glucose and insulin measurements and every hour for 10 hours for retinyl palmitate and lipid measurements. Results are reported for the first eight patients.

Three-day fecal collections were made on an outpatient basis at the end of week 15 of both metabolic diets, placed on frozen carbon dioxide in a polystyrene container, and returned by courier to the laboratory, where the samples were weighed and stored at -20 °C before freeze-drying. Seventy-four complete three-day collections were obtained, of a possible total of 86 for both metabolic diets. Seven subjects provided only two-day collections for one or both diets, one subject provided a single-day collection during the soluble-fiber diet, and one subject did not collect his feces. Values for feces are expressed as mean output per day.

On completing both metabolic diets, the subjects were asked to rate their feelings of satiety using a seven-point scale, with -3 representing extremely hungry, 0 neutral, and +3 completely satiated.

The study was approved by the ethics committee of the University of Toronto. Informed consent was obtained from all the subjects.

Diet

The two metabolic diets shared a common core, to which foods high in soluble or insoluble fiber or prepared dishes containing the fiber under study were added. Our aim was to provide 20 percent or less of the dietary calories as fat, 20 percent as protein, and 60 percent or more as available carbohydrate (with 2.5 to 3 g of fiber per 100 kcal), and to provide less than 50 mg of dietary cholesterol daily. Two-week repeating menus were planned to suit individual tastes.

The foods high in soluble fiber were barley, dried lentils, peas and beans in precooked form (as instant soups, in cans or glass jars, or as frozen dinners such as kidney-bean chili), oat bran, and a commercially available breakfast cereal enriched with psyllium. The foods high in insoluble fiber included a wheat-bran breakfast cereal, high-fiber crackers, and a high-fiber bread containing fine ground wheat bran and added gluten, chosen to resemble the nutrient profile of dried legumes. The gluten was added to maintain the same proportion of vegetable protein in both diets.

Very low intakes of fat and cholesterol were achieved through the use of low-fat dairy foods (skim milk, low-fat yogurt, cottage cheese, and skim-milk cheese) and vegetable-protein products (including soybean products, tofu, and foods containing wheat gluten). We assessed caloric requirements using standard Lipid Research Clinics tables,11 with adjustment for the subject's physical activity and seven-day dietary record. We devised the diets using a data base in which the majority of the foods had been analyzed in the laboratory with Association of Official Analytical Chemists methods for macronutrients12 and fiber13. The fatty-acid composition was determined by gas chromatography14. The food-composition tables of the U.S. Department of Agriculture were used15 for foods that had not been analyzed directly. The percentage figures for soluble and insoluble fiber were derived from tables16 and were applied to our values for total dietary fiber to give the absolute amounts of soluble and insoluble fiber. Certain products that were not listed in the tables were analyzed specifically for soluble and insoluble fiber13. At each clinic visit, the dietitian assessed compliance using the subject's menus, on which each food was checked when eaten. Additional items were noted in a blank column opposite the prescribed diet. Body weight was measured at each clinic visit, and the results were used to adjust total caloric intake. All diet foods were packed at a central location and delivered weekly by courier to the subjects' homes at a time convenient to them.

Analyses

Total, LDL, and high-density lipoprotein (HDL) cholesterol and triglyceride were measured in fresh plasma after ultracentrifugal flotation into fractions with densities of ≤ 1.006 and >1.006 g per milliliter on the day of collection. Quality-control procedures were followed as described in the Manual of Laboratory Operations of the Lipid Research Clinics17. Apolipoproteins AI and B were measured by nephelometry at the end of the study in serum stored at -70 °C18. The average within-run coefficients of variation, as determined in seven runs with six replicates per run for each of three pools, were 3.36 percent for apolipoprotein AI (range, 3.04 to 3.54) and 2.74 percent for apolipoprotein B (range, 1.82 to 2.91). Serum samples from each subject were analyzed in a single batch. Lipoprotein(a) was measured with a commercial enzyme-linked immunosorbent assay (Terumo, Elkton, Md.).

Fecal acidic and neutral sterols were measured in finely ground freeze-dried feces from the three-day collections after extraction, thin-layer chromatography, and methylation and trimethylsylylation for bile acids and neutral steroids followed by gas-liquid chromatography with a DB-1 column (J&W Scientific, Folsom, Calif.), with 5beta-cholinic acid and 5alpha-cholestane, respectively, as internal standards5.

Glucose was measured in capillary blood19. Serum insulin20 and urinary C-peptide21 levels were estimated by radioimmunoassay at the end of the study in samples stored at -70 °C. Serum formate and acetate were measured by high-performance liquid chromatography22. Retinyl palmitate was measured in duplicate in the chylomicron fraction and the fractions with flotation coefficients of <400 and densities of ≤ 1.006 or >1.006 g per milliliter by high-performance liquid chromatography23.

Statistical Analysis

The results are expressed as means ±SE. Weight change in grams per week was estimated for each metabolic diet from the regression of each subject's body weight against time. The significance of the difference between diets was assessed by Student's t-test (two tailed) for paired data and by the general-linear-model procedure with SAS software,24 with sex and base-line values included in the basic model as covariates. Weight change and total caloric intake were also included in mechanistic analyses to allow for differences between diets in amount of exercise.

Results

Table 1. Table 1. Mean (±SE) Daily Intake of the Study Diets.

A total of 22 subjects received the soluble-fiber diet first, and 21 received the insoluble-fiber diet first. The diets were well accepted, and compliance was good, as judged by close agreement between the macronutrient profile of the prescribed diets and the diet recorded as consumed (Table 1). On the soluble-fiber and insoluble-fiber diets, the subjects consumed 91.4 ±1.4 percent and 91.4 ±1.6 percent, respectively, of the calories prescribed. The corresponding figures for total fiber were 91.6 ±1.5 percent and 90.9 ±1.8 percent.

During both diets, the subjects ate as much food as they desired. The satiety rating was 1.8 ±0.2 units for the soluble-fiber diet and 1.5 ±0.2 units for the insoluble-fiber diet. There was a mean weight loss of 29 ±16 g per week with the soluble-fiber diet and 62 ±19 g per week with the insoluble-fiber diet. This difference approached significance (P = 0.058).

Fasting Blood Lipids and Apolipoproteins

Figure 1. Figure 1. Mean (±SE) Fasting Blood Lipid and Lipoprotein Levels during the Soluble-Fiber Diet (open circle) and the Insoluble-Fiber Diet (solid circle).

To convert values for cholesterol to milligrams per deciliter, multiply by 38.67.

Table 2. Table 2. Mean (±SE) Plasma Lipid and Lipoprotein Levels before and during the Study Diets, Day-Profile Measurements, and Fecal Bile Acid Output at the End of Both Diets.

During both diets, blood lipids had fallen to their lowest levels by week 4 (Figure 1). These declines were sustained for the remaining three months of each study period (Figure 1). Simple paired comparison showed that the mean lipid values from week 4 to week 16 of the soluble-fiber diet were in general lower than the values during the insoluble-fiber diet (Table 2). The percentage differences between dietary periods were as follows: total cholesterol, 4.9 ±0.9 percent (P<0.001); LDL cholesterol, 4.8 ±1.3 percent (P<0.001); HDL cholesterol, 3.4 ±1.3 percent (P = 0.014); ratio of total cholesterol to HDL cholesterol, 0.7 ±1.4 percent (P = 0.60); triglyceride, 1.3 ±2.5 percent (P = 0.59); apolipoprotein AI, 3.3 ±1.0 percent (P = 0.001); apolipoprotein B, 5.8 ±1.1 percent (P = 0.001); ratio of apolipoprotein B to apolipoprotein AI, 2.3 ±1.3 percent (P = 0.07); and lipoprotein(a) levels, 3.2 ±2.3 percent (P = 0.17). When the significant differences were expressed as absolute values, their significance was maintained, and the reduction in the ratio of apolipoprotein B to apolipoprotein AI was also significant (P = 0.001) after adjustment for sex and base-line values in the general linear model (Table 2).

After additional adjustment (for weight change and caloric intake), the ratio of total cholesterol to HDL cholesterol and the lipoprotein(a) level were significantly lower during the soluble-fiber diet than during the insoluble-fiber diet (P = 0.011 and P = 0.021, respectively).

The men had greater percentage reductions than the women for total and LDL cholesterol and apolipoprotein B when following the soluble-fiber as compared with the insoluble-fiber diet (respective reductions among the men: 7.5 ±1.2 percent, P<0.001; 9.6 ±1.9 percent, P<0.001; and 9.2 ±1.5 percent, P<0.001; among the women: 3.4 ±1.2 percent, P = 0.008; 2.2 ±1.4 percent, P = 0.141; and 4.0 ±1.4 percent, P = 0.006) (Figure 1). These percentage differences were all significantly greater for the men than for the women (P = 0.033, P = 0.004, and P = 0.024, respectively).

The 22 subjects with only a high LDL cholesterol level had a significant percentage difference in LDL cholesterol between the soluble-fiber and insoluble-fiber diets (4.6 ±1.3 percent, P = 0.001); there was a similar but nonsignificant reduction in the 14 subjects who had high LDL cholesterol and triglyceride levels (2.6 ±2.7 percent, P = 0.351).

Five subjects were classified as having the E3/E2 genotype, 18 were homozygous for E3, and 20 either had E4/E3 (n = 18) or were homozygous for E4 (n = 2). E3 homozygotes and E4 carriers had similar percentage reductions in LDL cholesterol levels (5.4 ±2.0 percent [P = 0.017] vs. 5.4 ±1.1 percent [P<0.001], respectively).

Fecal Bile Acids and Neutral Steroids

Figure 2. Figure 2. Mean (±SE) Differences between the Soluble-Fiber Diet and the Insoluble-Fiber Diet in the Excretion of Bile Acids and Neutral Sterols at Week 15.

Values represent measurements in 42 subjects and are the results obtained during the soluble-fiber diet minus the results obtained during the insoluble-fiber diet. LC denotes lithocholic acid, DC deoxycholic acid, CDC chenodeoxycholic acid, C cholic acid, UDC ursodeoxycholic acid, CL coprostanol, CH cholesterol, and CNE coprostanone.

Total fecal excretion of bile acid was 83 ±14 percent higher during the soluble-fiber diet than during the insoluble-fiber diet (241 ±27 vs. 147 ±16 mg per day, P<0.001) (Table 2). The output of bile acid among the men was significantly greater than the output among the women during both the soluble-fiber diet (P = 0.008) and the insoluble-fiber diet (P = 0.014). For men (n = 14), the percentage increase in fecal bile acid excretion during the soluble-fiber diet as compared with the insoluble-fiber diet was 75 ±15 percent (341 ±56 vs. 202 ±36 mg per day, P<0.001); and for women (n = 28) the corresponding increase was 88 ±19 percent (190 ±26 vs. 119 ±15 mg per day, P<0.001). These differences were reflected in values for the individual bile acids (Figure 2).

Total excretion of neutral steroids was similar during both diets: 441 ±34 mg per day during the soluble-fiber diet and 431 ±35 mg per day during the insoluble-fiber diet (Figure 2). The mean fecal cholesterol excretion was 38 ±18 percent higher during the soluble-fiber diet than during the insoluble-fiber diet, a difference that was marginally significant (134 ±21 vs. 113 ±14 mg per day, P = 0.047).

Figure 3. Figure 3. Relation between the Difference in Plasma Total Cholesterol and the Difference in Daily Fecal Bile Acid Excretion between the Soluble-Fiber Diet and the Insoluble-Fiber Diet.

Values represent measurements in 42 men (solid circle) and women (solid squares). To convert values for cholesterol to millimoles per liter, divide by 38.67.

The difference between diets in fecal bile acid output was significantly related to the differences in total and LDL cholesterol levels and apolipoprotein B levels (r = -0.42, P = 0.005; r = -0.49, P<0.001; and r = -0.33, P = 0.035, respectively; n = 42) (Figure 3). No significant difference between diets was seen in mean fecal wet weight.

Other Tests

The reduction in fasting total and LDL cholesterol levels during the soluble-fiber diet was maintained in the 11 subjects whose day profiles were studied. No differences were seen between the mean levels of short-chain fatty acids, blood glucose, serum insulin, or 24-hour urinary C peptide.

In the eight subjects studied, the area under the chylomicron-triglyceride response curve was significantly greater after the soluble-fiber diet than after the insoluble-fiber diet (5.60 ±1.16 vs. 4.4 ±1.12 mmol-hr per liter, P = 0.024), but in none of the lipid fractions measured did the difference in retinyl palmitate levels reach significance.

No difference was seen in the postprandial blood glucose or serum insulin responses assessed as part of the fat-tolerance test.

Discussion

Our study shows that a diet containing a high amount of soluble fiber, as compared with a diet high in insoluble fiber, reduced plasma LDL cholesterol and apolipoprotein B levels. Part of the value of soluble fiber may be in replacing saturated fat and cholesterol in the diet1. However, even after dietary saturated fat and cholesterol have been reduced, a further reduction in blood lipid levels can result from the consumption of foods high in soluble fiber. These data therefore support current recommendations to increase the consumption of soluble-fiber foods in the context of a low-fat, low-cholesterol diet.

Levels of LDL cholesterol and apolipoprotein B fell in the subjects who consumed the maximal acceptable amounts of foods rich in soluble fiber in diets that were already very low in saturated fat and cholesterol. These reductions in blood lipid levels were generally well maintained. HDL cholesterol and apolipoprotein AI levels also fell. Similar decreases in HDL cholesterol have also been seen consistently in studies involving dried legumes25. Some reduction in HDL cholesterol is associated with many of the currently recommended dietary changes that reduce serum lipid levels,26 and this has prompted the development of additional strategies27,28. Lower total cholesterol and apolipoprotein B levels relative to HDL cholesterol and apolipoprotein AI levels are associated with a reduced risk of coronary heart disease29-34. The lipid changes we observed, although small, provide additional support for dietary advice to increase the intake of foods high in soluble fiber. Qualitatively similar lipid changes were noted in studies on the regression of human arteriosclerosis that incorporated dietary change35-37. It has been suggested that a 5-to-10-g increase in dietary soluble fiber will reduce serum total cholesterol by approximately 5 percent,38 a reduction comparable to that observed in our study.

A further reason for concern over claims that dietary fiber has a lipid-lowering effect is the lack of a clear mechanism. Originally, it was proposed that fiber increased the binding and fecal loss of bile acids39. Soluble fibers increase the fecal output of bile acids9 and the size of the bile acid pool,40 but the increased steroid losses (20 to 80 percent) have not been considered sufficient to account fully for the reduction in plasma cholesterol levels9. However, the larger differences in fiber-induced sterol losses observed in our study could contribute to the reduction in plasma cholesterol, as indicated by the significant relation between increased loss of bile acid and reduced serum lipid levels.

There is concern that increasing concentrations of fecal bile acids may enhance the risk of colon cancer9. In our subjects, however, the concentration of total bile acids during the soluble-fiber diet was, if anything, lower than that observed during the prestudy Step 2 diet.

Men had greater lipid reductions than women during the soluble-fiber diet. Nonetheless, there was no significant difference in response to the diets on the basis of lipid phenotypes or apolipoprotein E polymorphism.

The fiber intakes in our study were higher than those generally recommended,9 and the levels of saturated fat and cholesterol were lower than those normally advised even in therapeutic situations1. After marked reductions in the intake of saturated fat and cholesterol, the additional lipid-lowering effect of fiber was small. Other studies have noted greater reductions in serum lipid levels with lower intakes of fiber in subjects following more normal diets5,9.

Funding and Disclosures

Supported by grants from the Heart, Lung, and Blood Institute, National Institutes of Health (R01 HL 39689), and Loblaw Companies Limited.

We are indebted to the following companies for the donation of products: Archer Daniels Midland, Decatur, Ill.; Danby Products, Guelph, Ont.; Kellogg Company, Battle Creek, Mich., for breakfast cereals; President's Choice Too Good To Be True Products, Loblaw International Merchants, Toronto; Lumen Food Corporation, Lake Charles, La.; Mandarin Enterprises, Richmond, B.C.; MGM Brands, Scarborough, Ont.; Nestle, Don Mills, Ont., and Vevey, Switzerland; Spring Creek Natural Foods, Spencer, W.Va.; Uncle Ben's, Toronto; Westbrae Natural Foods, Commerce, Calif.; Will-Pak Foods, San Pedro, Calif.; Yves Fine Foods, Vancouver, B.C.; and T.J. Lipton, Toronto. We are also indebted to Mr. Larry Griffin and Mr. Bill Snelling for help in carrying out the study and ensuring quality control, and to Mrs. Anna Maria Spadafora and her team, whose diligence in diet preparation made this study possible.

Author Affiliations

From the Departments of Nutritional Sciences (D.J.A.J., T.M.S.W., A.V.R., S.J.M., T.P.P.R., D.L.B., P.J.S., C.M., L.K.R.) and Preventive Medicine and Biostatistics (P.C.), Faculty of Medicine, University of Toronto, Toronto; the Clinical Nutrition and Risk Factor Modification Center (D.J.A.J., T.M.S.W., R.A.H., A.L.J.) and Division of Endocrinology and Metabolism (D.J.A.J., T.M.S.W., R.A.H., P.W.C.), St. Michael's Hospital, University of Toronto, Toronto; the Department of Foods and Nutrition, Purdue University, West Lafayette, Ind. (J.A.S., E.J.F.); and the Carbohydrate Research Division, Nestle Research Center, Lausanne, Switzerland (P.W.).

Address reprint requests to Dr. David Jenkins at the Clinical Nutrition and Risk Factor Modification Center, St. Michael's Hospital, 61 Queen St. East, Toronto, ON M5C 2T2, Canada.

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Citing Articles (195)

    Figures/Media

    1. Table 1. Mean (±SE) Daily Intake of the Study Diets.
      Table 1. Mean (±SE) Daily Intake of the Study Diets.
    2. Figure 1. Mean (±SE) Fasting Blood Lipid and Lipoprotein Levels during the Soluble-Fiber Diet (open circle) and the Insoluble-Fiber Diet (solid circle).
      Figure 1. Mean (±SE) Fasting Blood Lipid and Lipoprotein Levels during the Soluble-Fiber Diet (open circle) and the Insoluble-Fiber Diet (solid circle).

      To convert values for cholesterol to milligrams per deciliter, multiply by 38.67.

    3. Table 2. Mean (±SE) Plasma Lipid and Lipoprotein Levels before and during the Study Diets, Day-Profile Measurements, and Fecal Bile Acid Output at the End of Both Diets.
      Table 2. Mean (±SE) Plasma Lipid and Lipoprotein Levels before and during the Study Diets, Day-Profile Measurements, and Fecal Bile Acid Output at the End of Both Diets.
    4. Figure 2. Mean (±SE) Differences between the Soluble-Fiber Diet and the Insoluble-Fiber Diet in the Excretion of Bile Acids and Neutral Sterols at Week 15.
      Figure 2. Mean (±SE) Differences between the Soluble-Fiber Diet and the Insoluble-Fiber Diet in the Excretion of Bile Acids and Neutral Sterols at Week 15.

      Values represent measurements in 42 subjects and are the results obtained during the soluble-fiber diet minus the results obtained during the insoluble-fiber diet. LC denotes lithocholic acid, DC deoxycholic acid, CDC chenodeoxycholic acid, C cholic acid, UDC ursodeoxycholic acid, CL coprostanol, CH cholesterol, and CNE coprostanone.

    5. Figure 3. Relation between the Difference in Plasma Total Cholesterol and the Difference in Daily Fecal Bile Acid Excretion between the Soluble-Fiber Diet and the Insoluble-Fiber Diet.
      Figure 3. Relation between the Difference in Plasma Total Cholesterol and the Difference in Daily Fecal Bile Acid Excretion between the Soluble-Fiber Diet and the Insoluble-Fiber Diet.

      Values represent measurements in 42 men (solid circle) and women (solid squares). To convert values for cholesterol to millimoles per liter, divide by 38.67.

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