No glycemic benefit from guar administration in NIDDM

Effect of viscous soluble dietary fiber on glucose and lipid metabolism in patients with type 2 diabetes mellitus: a systematic review and meta-analysis on randomized clinical trials

Background

The effect of viscous soluble dietary fiber on glucose and lipid metabolism in type 2 diabetes mellitus (T2DM) remains controversial, and the dose-response relationship of its effect on blood glucose and blood lipid level is still unclear.

Methods

We conducted comprehensive searches in several databases up to 17 January 2023. We conducted a dose-response analysis of randomized controlled trials (RCTs) to investigate the effect of viscous dietary fiber on glucose and lipid metabolism in patients with T2DM.

Results

Statistical significance was observed in the decreases of glycosylated hemoglobin (HbA1c) (mean difference) [MD = -0.47; 95%CI: (-0.66, -0.27)], fasting blood glucose (FBG) [MD = -0.93; 95%CI: (-1.46, -0.41)], total cholesterol (TC) [MD = -0.33; 95%CI: (-0.46, -0.21)], and low-density lipoprotein and cholesterol (LDL-C) [MD = -0.24; 95%CI: (-0.35, -0.13)]. Contrarily, no difference was observed regarding the level of high-density lipoprotein cholesterol (HDL-C) or triglyceride (TG). In addition, the effect on fasting insulin remains unclear. Results from the subgroup analyses showed that an intervention duration longer than 6 weeks had a significant effect on the HbA1c level; a treatment dosage higher than 8.3 g/day had a significant effect on the FBG level.

Conclusions

Supplementation of viscous dietary fiber is beneficial to control blood glucose and blood lipid in T2DM.

The effects of guar gum supplementation on glycemic control, body mass and blood pressure in adults: A GRADE-assessed systematic review and meta-analysis of randomized clinical trials

BACKGROUND

This systematic review and meta-analysis sought to evaluate the effects ofguar gum supplementation on glycemic control, blood pressure, and body mass in adults.

METHODS

Relevant studies were obtained by searching the PubMed, SCOPUS, Embase, and Web of Science databases (from inception to January 2022). Weighted mean differences (WMD) and 95% confidence intervals (CIs) were pooled using a random-effects model. Heterogeneity, sensitivity analysis, and publication bias were reported using standard methods.

RESULTS

Pooled analysis of 14 randomized controlled trials (RCTs) revealed that guar gum supplementation led to significant reductions in hemoglobin A1c (HbA1c) (WMD: -0.47 mg/dL, 95% CI: -0.75, -0.18, p = 0.001). However, there was no effect on fasting blood sugar (FBS), systolic and diastolic blood pressure, and body mass among adults in comparison with the control group. A subgroup analysis demonstrated that intervention in patients with type 2 diabetes (T2DM), and high supplementation dosages (>15 g/d) significantly decreased FBS concentrations, but not in other subgroups.

CONCLUSION

Guar gum supplementation may yield a beneficial effect on glycemic control in T2DM patients. However, the extant clinical trials, thus far, are not sufficient enough to form guidelines for clinical practice.

The role of selected nutraceuticals in management of prediabetes and diabetes: An updated review of the literature

Dysglycemia is a disease state preceding the onset of diabetes and includes impaired fasting glycemia and impaired glucose tolerance. This review aimed to collect and analyze the literature reporting the results of clinical trials evaluating the effects of selected nutraceuticals on glycemia in humans. The results of the analyzed trials, generally, showed the positive effects of the nutraceuticals studied alone or in association with other supplements on fasting plasma glucose and post-prandial plasma glucose as primary outcomes, and their efficacy in improving insulin resistance as a secondary outcome. Some evidences, obtained from clinical trials, suggest a role for some nutraceuticals, and in particular Berberis, Banaba, Curcumin, and Guar gum, in the management of prediabetes and diabetes. However, contradictory results were found on the hypoglycemic effects of Morus, Ilex paraguariensis, Omega-3, Allium cepa, and Trigonella faenum graecum, whereby rigorous long-term clinical trials are needed to confirm these data. More studies are also needed for Eugenia jambolana, as well as for Ascophyllum nodosum and Fucus vesiculosus which glucose-lowering effects were observed when administered in combination, but not alone. Further trials are also needed for quercetin.

Could Dietary Modification Independent of Energy Balance Influence the Underlying Pathophysiology of Type 2 Diabetes? Implications for Type 2 Diabetes Remission

High-quality clinical trial data demonstrate that remission is possible for people living with type 2 diabetes (T2D) if they lose a large amount of weight (≥ 10 kg). Durable remission appears predicated on the long-term maintenance of weight loss. Unfortunately, long-term follow-up data from lifestyle-based weight loss programmes show that, on average, most people regain at least some of the weight lost. In addition, restoration of a diminished first-phase insulin response also appears necessary for durable remission, and this becomes less likely as T2D progresses. A pragmatic approach to enhance the effects of weight loss on durable remission is to consider whether dietary components could help control blood glucose, independent of caloric balance. This manuscript reviews current evidence on weight-neutral effects of diet on blood glucose, including high-protein, low-carbohydrate, high-fibre and plant-based diets, with a particular focus on the effect of nutrition on the underlying pathophysiology of T2D, including the first-phase insulin response. The importance of mechanistic data in enhancing our understanding of dietary strategies in T2D remission is described, and suggestions are made for future advances in remission research.

Effects of soluble fiber supplementation on glycemic control in adults with type 2 diabetes mellitus: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND & AIMS

Soluble dietary fiber is prompted as an important part of reducing blood glucose, ameliorating insulin resistance and controlling body weight. Thus, we performed this systematic review and meta-analysis of randomized controlled trials (RCTs) to quantify and synthesize the effects of soluble fiber supplementation on glycemic control and BMI modification in adults with type 2 diabetes.

METHODS

We searched MEDLINE, Embase, Web of Science, ClinicalTrials.gov, and Cochrane databases until February 13, 2020 to identify RCTs that detected the effects of soluble fiber supplementation on glycemic control in adults with type 2 diabetes. A random-effects model with the generic inverse variance method was used to analyze the pooled data. The meta-regression and subgroup analyses were conducted to identify the variables that influenced the pooled results. The robust error meta-regression model was used to conduct the dose-response test. The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) system was undertaken to evaluate the overall quality of the evidence.

RESULTS

A total of 29 RCTs (33 comparisons) involving 1517 participants were identified in this meta-analysis. Results showed that supplemental soluble dietary fiber significantly reduced glycosylated hemoglobin (HbA1c, MD -0.63%, 95% CI [-0.90, -0.37]; P < 0.00001), fasting plasma glucose (FPG, MD -0.89 mmol/L, 95% CI [-1.28, -0.51]; P < 0.00001), fasting insulin (SMD -0.48, 95% CI [-0.80, -0.17]; P = 0.003), homeostatic model assessment of insulin resistance (HOMA-IR, SMD -0.58, 95% CI [-0.86, -0.29], P < 0.0001), fructosamine (SMD -1.03, 95% CI [-1.51, -0.55]; P < 0.0001), 2-h postprandial plasma glucose (SMD -0.74, 95% CI [-1.00, -0.48]; P < 0.00001), and BMI (SMD -0.31, 95% CI [-0.61, -0.00], P = 0.05) compared with control diets in patients with type 2 diabetes. Specifically, dose-response meta-analyses presented that a daily dosage of 7.6-8.3 g was recommended.

CONCLUSION

Intake of soluble fiber supplementation is effective in improving glycemic control and BMI level in type 2 diabetes and is also a convenient way to help individuals meet standard dietary fiber needs. But due to the evidence of substantial heterogeneity in most pooled estimates, further long-term and high-quality RCTs are needed.

Should Viscous Fiber Supplements Be Considered in Diabetes Control? Results From a Systematic Review and Meta-analysis of Randomized Controlled Trials

OBJECTIVE

Evidence from randomized controlled trials (RCTs) suggests that viscous dietary fiber may offer beneficial effects on glycemic control and, thus, an improved cardiovascular disease risk profile. Our purpose was to conduct a systematic review and meta-analysis of RCTs to synthesize the therapeutic effect of viscous fiber supplementation on glycemic control in type 2 diabetes.

RESEARCH DESIGN AND METHODS

MEDLINE, Embase, and Cochrane Central Register of Controlled Trials were searched through 15 June 2018. We included RCTs ≥3 weeks in duration that assessed the effects of viscous fiber on markers of glycemic control in type 2 diabetes. Two independent reviewers extracted data. Data were pooled using the generic inverse variance method and expressed as mean differences (MD) with 95% CIs. Heterogeneity was assessed (Cochran Q statistic) and quantified (I ² statistic). The Grading of Recommendations Assessment, Development, and Evaluation (GRADE) approach was used to evaluate the overall certainty of the evidence.

RESULTS

We identified 28 eligible trial comparisons (n = 1,394). Viscous fiber at a median dose of ∼13.1 g/day significantly reduced HbA_1c (MD -0.58% [95% CI -0.88, -0.28]; P = 0.0002), fasting blood glucose (MD -0.82 mmol/L [95% CI -1.32, -0.31]; P = 0.001), and HOMA-insulin resistance (IR) (MD -1.89 [95% CI -3.45, -0.33]; P = 0.02) compared with control and in addition to standard of care. The certainty of evidence was graded moderate for HbA_1c, fasting glucose, fasting insulin, and HOMA-IR and low for fructosamine.

CONCLUSIONS

Viscous fiber supplements improve conventional markers of glycemic control beyond usual care and should be considered in the management of type 2 diabetes.

The Effects of Prebiotics and Substances with Prebiotic Properties on Metabolic and Inflammatory Biomarkers in Individuals with Type 2 Diabetes Mellitus: A Systematic Review

BACKGROUND

Intestinal bacteria composition and prebiotics may play a role in the management of type 2 diabetes mellitus (T2DM).

OBJECTIVE

The objective of this systematic review was to evaluate the effect of prebiotics and substances with prebiotic properties on the metabolic and inflammatory biomarkers of individuals with T2DM compared with placebo.

METHODS

A literature search to identify articles published up to March 31, 2018, was conducted utilizing PubMed, Science Direct, and Cochrane Central Register of Controlled Trials. Individuals at aged 18 years or older with T2DM from randomized controlled trials investigating prebiotics or substances with prebiotic properties were included. Metabolic and inflammatory biomarkers associated with T2DM were the primary outcome measures.

RESULTS

Twenty-seven publications were analyzed. All but seven of these publications reported a beneficial effect on metabolic and/or inflammatory biomarkers. Interventions included mostly women, lasted 4 days to 12 weeks, and diabetes duration ranged from 6 months to 11 years. Nineteen publications reported improvements in glycemia, 15 in cardiovascular markers, nine in body weight, and nine in inflammatory markers. Benefits from resistant starch, resistant dextrin, and oligofructose-enriched inulin were most frequent. A smaller number of studies utilizing other substances with prebiotic properties also yielded improvements.

CONCLUSIONS

Based on these results, there is fair evidence that prebiotics and substances with prebiotic properties may improve metabolic and inflammatory biomarkers related to T2DM in women aged 18 years at least. Interventions with resistant starch, resistant dextrin, and oligofructose-enriched inulin exhibited the strongest evidence for improvements due to the quantity of publications and quality grades. Other prebiotics and substances with prebiotic properties show promise but the number of studies is few. Additional studies that are longer in duration, include both sexes, and include other prebiotics or substances with prebiotic properties are needed.

Impact of diet restriction in the management of diabetes: evidences from preclinical studies

The inappropriate dietary habits lead to the onset of age-related pathologies which include diabetes and cardiovascular ailments. Dietary restriction and nutritional therapy play an important role in the prevention of these chronic ailments. Preclinical research provides a basis for the therapeutic exploration of new dietary interventions for the clinical trials to potentiate the scientific management of diabetes and its related complications which further help in translating these nutritional improvements from bench to bedside. Within the same context, numerous therapeutically proved preclinical dietary interventions like high-fiber diet, caloric restriction, soy isoflavone-containing diets, etc., have shown the promising results for the management of diabetes and the associated complications. The focus of the present review is to highlight the various preclinical evidences of diet restriction for the management of diabetes and which will be helpful for enlightening the new ideas of nutritional therapy for future research exploration. In addition, some potential approaches are also discussed which are associated with various nutritional interventions to combat progressive diabetes and the associated disorders. Graphical abstract ᅟ.

Ayurvedic treatments for diabetes mellitus

BACKGROUND

Patients with diabetes frequently use complimentary and alternative medications including Ayurvedic medications and hence it is important to determine their efficacy and safety.

OBJECTIVES

To assess the effects of Ayurvedic treatments for diabetes mellitus.

SEARCH METHODS

We searched The Cochrane Library (issue 10, 2011), MEDLINE (until 31 August 2011), EMBASE (until 31 August 2011), AMED (until 14 October 2011), the database of randomised trials from South Asia (until 14 October 2011), the database of the grey literature (OpenSigle, until 14 October 2011) and databases of ongoing trials (until 14 October 2011). In addition we performed hand searches of several journals and reference lists of potentially relevant trials.

SELECTION CRITERIA

We included randomized trials of at least two months duration of Ayurvedic interventions for diabetes mellitus. Participants of both genders, all ages and any type of diabetes were included irrespective of duration of diabetes, antidiabetic treatment, comorbidity or diabetes related complications.

DATA COLLECTION AND ANALYSIS

Two authors independently extracted data. Risk of bias of trials was evaluated as indicated in the Cochrane Handbook for Systematic Reviews of Intervention.

MAIN RESULTS

Results of only a limited number of studies could be combined, in view of different types of interventions and variable quality of data. We found six trials of proprietary herbal mixtures and one of whole system Ayurvedic treatment. These studies enrolled 354 participants ( 172 on treatment, 158 on controls, 24 allocation unknown). The treatment duration ranged from 3 to 6 months. All these studies included adults with type 2 diabetes mellitus.With regard to our primary outcomes, significant reductions in glycosylated haemoglobin A1c (HbA1c), fasting blood sugar (FBS) or both were observed with Diabecon, Inolter and Cogent DB compared to placebo or no additional treatment, while no significant hypoglycaemic response was found with Pancreas tonic and Hyponidd treatment. The study of whole system Ayurvedic treatment did not provide data on HbA1c and FBS values. One study of Pancreas tonic treatment did not detect a significant change in health-related quality of life. The main adverse effects reported were drug hypersensitivity (one study, one patient in the treatment arm); hypoglycaemic episodes (one study, one participant in the treatment arm; none had severe hypoglycaemia) and gastrointestinal side effects in one study (1 of 20 in the intervention group and 0 of 20 participants in the control group). None of the included studies reported any deaths, renal, hematological or liver toxicity.With regard to our secondary outcomes, post prandial blood sugar (PPBS) was lower among participants treated with Diabecon, was unchanged with Hyponidd and was higher in patients treated with Cogent DB. Treatment with Pancreas tonic and Hyponidd did not affect lipid profile significantly, while patients treated with Inolter had significantly higher HDL- and lower LDL-cholesterol as well as lower triglycerides. Cogent DB treated participants also had lower total cholesterol and triglycerides.Studies of treatment with Diabecon reported increased fasting insulin levels; one study of treatment with Diabecon reported higher stimulated insulin levels and fasting C-peptide levels in the treatment group. There was no significant difference in fasting and stimulated C-peptide and insulin levels with Hyponidd, Cogent DB and Pancreas tonic treatment. The study of Inolter did not assess these outcomes.No study reported on or was designed to investigate diabetic complications, death from any cause and economic data.

AUTHORS' CONCLUSIONS

Although there were significant glucose-lowering effects with the use of some herbal mixtures, due to methodological deficiencies and small sample sizes we are unable to draw any definite conclusions regarding their efficacy. Though no significant adverse events were reported, there is insufficient evidence at present to recommend the use of these interventions in routine clinical practice and further studies are needed.

Effects of dietary fibre on subjective appetite, energy intake and body weight: a systematic review of randomized controlled trials

Dietary fibres are believed to reduce subjective appetite, energy intake and body weight. However, different types of dietary fibre may affect these outcomes differently. The aim of this review was to systematically investigate the available literature on the relationship between dietary fibre types, appetite, acute and long-term energy intake, and body weight. Fibres were grouped according to chemical structure and physicochemical properties (viscosity, solubility and fermentability). Effect rates were calculated as the proportion of all fibre-control comparisons that reduced appetite (n = 58 comparisons), acute energy intake (n = 26), long-term energy intake (n = 38) or body weight (n = 66). For appetite, acute energy intake, long-term energy intake and body weight, there were clear differences in effect rates depending on chemical structure. Interestingly, fibres characterized as being more viscous (e.g. pectins, β-glucans and guar gum) reduced appetite more often than those less viscous fibres (59% vs. 14%), which also applied to acute energy intake (69% vs. 30%). Overall, effects on energy intake and body weight were relatively small, and distinct dose-response relationships were not observed. Short- and long-term effects of dietary fibres appear to differ and multiple mechanisms relating to their different physicochemical properties seem to interplay. This warrants further exploration.

[Dietary fibers: current trends and health benefits in the metabolic syndrome and type 2 diabetes]

Dietary fiber may contribute to both the prevention and treatment of type 2 diabetes mellitus (T2DM). In epidemiological studies the intake of insoluble fiber, but not the intake of soluble fiber, has been inversely associated with the incidence of T2DM. In contrast, in postprandial studies, meals containing sufficiently quantities of beta-glucan, psyllium, or guar gum have decreased insulin and glucose responses in both healthy individuals and patients with T2DM. Diets enriched sufficiently in soluble fiber may also improve overall glycemic control in T2DM. Insoluble fiber has little effect on postprandial insulin and glucose responses. Fiber increases satiety. In some studies, insoluble fiber has been associated with less weight gain over time. Limited cross-sectional evidence suggests an inverse relationship between intake of cereal fiber and whole-grains and the prevalence of the metabolic syndrome. Although long-term data from trials focusing on specifically dietary fiber are lacking, meeting current recommendations for a minimum fiber intake of 25 g/d based on a diet rich in whole grains, fruits and legumes will probably decrease the risk of obesity, the metabolic syndrome and T2DM.

Therapeutic effects of psyllium in type 2 diabetic patients

OBJECTIVE

The aim of this study was to evaluate the effects of psyllium in type 2 diabetic patients.

DESIGN

The study included three phases: phase 1 (1 week), phase 2 (treatment, 14 g fibre/day, 6 weeks) and phase 3 (4 weeks). At the end of each phase a clinical evaluation was performed after the ingestion of a test breakfast of 1824.2 kJ (436 kcal). Measurements included concentrations of blood glucose, insulin, fructosamine, GHbA(1c), C-peptide and 24 h urinary glucose excretion. In addition, uric acid, cholesterol and several mineral and vitamin concentrations were also evaluated.

SETTING

The study was performed at the Department of Pharmacology, Toxicology and Nursing at the University of León (Spain).

SUBJECTS

Twenty type 2 diabetic patients (12 men and 8 women) participated in the study with a mean age of 67.4 y for men and 66 y for women. The mean body mass index of men was 28.2 kg/m(2) and that of women 25.9 kg/m(2).

RESULTS

Glucose absorption decreased significantly in the presence of psyllium (12.2%); this reduction is not associated with an important change in insulin levels (5%). GHbA(1c), C-peptide and 24 h urinary glucose excretion decreased (3.8, 14.9 and 22.5%, respectively) during the treatment with fibre (no significant differences) as well as fructosamine (10.9%, significant differences). Psyllium also reduced total and LDL cholesterol (7.7 and 9.2%, respectively, significant differences), and uric acid (10%, significant difference). Minerals and vitamins did not show important changes, except sodium that increased significantly after psyllium administration.

CONCLUSIONS

The results obtained indicate a beneficial therapeutic effect of psyllium (Plantaben) in the metabolic control of type 2 diabetics as well as in lowering the risk of coronary heart disease. We also conclude that consumption of this fibre does not adversely affect either mineral or vitamin A and E concentrations. Finally, for a greater effectiveness, psyllium treatment should be individually evaluated.

Beneficial effects of high dietary fiber intake in patients with type 2 diabetes mellitus

BACKGROUND

The effect of increasing the intake of dietary fiber on glycemic control in patients with type 2 diabetes mellitus is controversial.

METHODS

In a randomized, crossover study, we assigned 13 patients with type 2 diabetes mellitus to follow two diets, each for six weeks: a diet containing moderate amounts of fiber (total, 24 g; 8 g of soluble fiber and 16 g of insoluble fiber), as recommended by the American Diabetes Association (ADA), and a high-fiber diet (total, 50 g; 25 g of soluble fiber and 25 g of insoluble fiber), containing foods not fortified with fiber (unfortified foods). Both diets, prepared in a research kitchen, had the same macronutrient and energy content. We compared the effects of the two diets on glycemic control and plasma lipid concentrations.

RESULTS

Compliance with the diets was excellent. During the sixth week, the high-fiber diet, as compared with the the sixth week of the ADA diet, mean daily preprandial plasma glucose concentrations were 13 mg per deciliter [0.7 mmol per liter] lower (95 percent confidence interval, 1 to 24 mg per deciliter [0.1 to 1.3 mmol per liter]; P=0.04) and mean median difference, daily urinary glucose excretion 1.3 g (0.23; 95 percent confidence interval, 0.03 to 1.83 g; P= 0.008). The high-fiber diet also lowered the area under the curve for 24-hour plasma glucose and insulin concentrations, which were measured every two hours, by 10 percent (P=0.02) and 12 percent (P=0.05), respectively. The high-fiber diet reduced plasma total cholesterol concentrations by 6.7 percent (P=0.02), triglyceride concentrations by 10.2 percent (P=0.02), and very-low-density lipoprotein cholesterol concentrations by 12.5 percent (P=0.01).

CONCLUSIONS

A high intake of dietary fiber, particularly of the soluble type, above the level recommended by the ADA, improves glycemic control, decreases hyperinsulinemia, and lowers plasma lipid concentrations in patients with type 2 diabetes.

Cholesterol-lowering effects of dietary fiber: a meta-analysis

BACKGROUND

The effects of dietary soluble fibers on blood cholesterol are uncertain.

OBJECTIVE

This meta-analysis of 67 controlled trials was performed to quantify the cholesterol-lowering effect of major dietary fibers.

DESIGN

Least-squares regression analyses were used to test the effect on blood lipids of pectin, oat bran, guar gum, and psyllium. Independent variables were type and amount of soluble fiber, initial cholesterol concentration, and other important study characteristics.

RESULTS

Soluble fiber, 2-10 g/d, was associated with small but significant decreases in total cholesterol [-0.045 mmol L(-1).g soluble fiber(-1) (95% CI: -0.054, -0.035)] and LDL cholesterol [-0.057 mmol.L(-1).g(-1) (95% CI: -0.070, -0.044)]. The effects on plasma lipids of soluble fiber from oat, psyllium, or pectin were not significantly different. We were unable to compare effects of guar because of the limited number of studies using 2-10 g/d. Triacylglycerols and HDL cholesterol were not significantly influenced by soluble fiber. Lipid changes were independent of study design, treatment length, and background dietary fat content.

CONCLUSIONS

Various soluble fibers reduce total and LDL cholesterol by similar amounts. The effect is small within the practical range of intake. For example, 3 g soluble fiber from oats (3 servings of oatmeal, 28 g each) can decrease total and LDL cholesterol by approximately 0.13 mmol/L. Increasing soluble fiber can make only a small contribution to dietary therapy to lower cholesterol.

Antidiabetic plants and their active constituents

Diabetes mellitus is a debilitating and often life-threatening disease with increasing incidence in rural populations throughout the world. A scientific investigation of traditional herbal remedies for diabetes may provide valuable leads for the development of alternative drugs and therapeutic strategies. Alternatives are clearly needed because of the inability of current therapies to control all of the pathological aspects of diabetes, and the high cost and poor availability of current therapies for many rural populations, particularly in developing countries. This review provides information on more than 1200 species of plants reported to have been used to treat diabetes and/or investigated for antidiabetic activity, with a detailed review of representative plants and some of great diversity of plant constituents with hypoglycemic activity, their mechanisms of action, methods for the bioassay of hypoglycemic agents, potential toxicity problems, and promising directions for future research on antidiabetic plants. The objective of this work is to provide a starting point for programs leading to the development of indigenous botanical resources as inexpensive sources for standardized crude or purified antidiabetic drugs, and for the discovery of lead compounds for novel hypoglycemic drug development.

Blood glucose, plasma insulin and sensory responses to guar-containing wheat breads: effects of molecular weight and particle size of guar gum

The effectiveness of guar gum in reducing post-prandial blood glucose and plasma insulin levels in human subjects seems to depend mainly on its ability to increase the viscosity of digesta in the small intestine. However, the precise relationship between the rheological properties of guar gum (either in vitro or in vivo) and the changes in blood metabolites and hormones is unknown. The aim of the present study, therefore, was to investigate the effects of wheat breads containing guar gum samples varying in molecular weight (Mw) and particle size (characteristics that strongly influence the rheological properties of guar gum) on post-prandial blood glucose and plasma insulin levels in healthy subjects. The sensory qualities of breads containing guar-gum flours of different Mw were also evaluated using a hedonic scoring technique. No significant differences in the post-prandial blood glucose responses were found between the control and guar breads. However, all the guar breads elicited significant (P less than 0.05) decreases in the post-prandial rise in plasma insulin, an effect that did not appear to be influenced by large variations in Mw or particle size of guar gum. Moreover, the sensory qualities of guar bread were markedly improved by using low Mw grades of guar gum.

Effect of method of administration of psyllium on glycemic response and carbohydrate digestibility

To determine whether there was any advantage to taking a soluble fiber supplement separate from food, as opposed to incorporated into a food, we used psyllium as a model, either taken in water just before a flaked bran cereal test meal, sprinkled on top of the cereal, or actually incorporated into the flake. In normal subjects, psyllium reduced the glycemic response when sprinkled onto or incorporated into the cereal, but not when taken before the cereal. Varying the amount of psyllium incorporated into the cereal from 0 to 20% resulted in a linear dose-dependent reduction of the glycemic index (GI) (GI = 101 -2.2 x % psyllium; r = 0.950; p less than 0.002). In subjects with diabetes, the blood-glucose-lowering effect of the psyllium flake cereal was similar to that in normal subjects. Mixing psyllium with the cereal or incorporating it into the cereal reduced the rate of digestion of bran flakes in vitro but was not associated with increased breath hydrogen levels in vivo as an index of rapid colonic fermentation. The bran flakes with psyllium incorporated was rated as no less palatable than the bran flakes cereal alone, and significantly more palatable (p less than 0.05) than taking psyllium in water before the cereal or sprinkling psyllium onto the cereal. These studies confirm earlier reports that viscous fibers must be intimately mixed with the food to have the effect of reducing blood glucose responses, and that the mechanism of action relates to a reduced rate of digestion rather than carbohydrate malabsorption.(ABSTRACT TRUNCATED AT 250 WORDS)

Importance of the rate of hydration of pharmaceutical preparations of guar gum; a new in vitro monitoring method

Dietary supplements of guar gum are known to improve blood glucose control in diabetic patients. The efficacy of guar is probably dependent mainly upon its capacity to hydrate rapidly and thus to increase viscosity in the small intestine post-prandially. Measurement of the rate of hydration in vitro might therefore be a useful index of the effectiveness of guar formulations. A simple method for monitoring the hydration rate of guar gum has been developed, which involves measuring the changes in viscosity at discrete time intervals over a period of 5 h using a Brookfield RVT rotoviscometer. Six different samples of guar gum (four pharmaceutical preparations and two food grades of guar flour) were hydrated in sealed glass jars rotated at 6 rev min-1 in order to prevent particle aggregation. Marked differences in hydration rate and ultimate (maximum) viscosity between the different guar samples were observed. Three of the four pharmaceutical preparations were lower in viscosity than the food grades of guar flour during the first 60 min of hydration. Two of the preparations hydrated so slowly that even after 5 h they attained viscosity levels of only 60% of their ultimate viscosity. These results may explain why some guar gum preparations are clinically ineffective.

Metabolic effects and clinical value of beet fiber treatment in NIDDM patients

In the present study a randomized cross-over design was used to determine the clinical usefulness of adding 16 g of beet fiber to the ordinary diet of non-insulin dependent diabetic (NIDDM) out-patients. In addition, fiber effects on the gastrointestinal hormone responses to a standardized test meal were evaluated. The study included five patients treated with diet alone and eight patients treated with diet and sulphonylurea (SU). Beet fiber supplementation resulted in a 10% reduction (P less than 0.01) of serum cholesterol in SU-treated patients. No differences were found for fasting blood glucose, glycated hemoglobin, serum triglycerides or body weight. In the diet-treated patients, fasting plasma somatostatin was elevated during the fiber period. However, postprandial responses of insulin, C-peptide, glucagon, gastric inhibitory peptide and somatostatin were not influenced by an increased fiber intake in any group. All patients experienced mild gastrointestinal discomfort during the fiber period. In view of the limited metabolic benefit of beet fiber treatment we conclude that there is little use for this type of dietary fiber in the routine treatment of patients with NIDDM.

The dietary treatment of diabetes mellitus

The most important dietary goal for individuals with type I diabetes mellitus is the establishment of a regular meal pattern with consistent day-to-day caloric and carbohydrate intake. Ideally, the diet should contain 55 to 60 per cent of total calories as carbohydrate, less than 30 per cent of calories as fat, less than 10 per cent of calories as saturated fat, and less than 300 mg of cholesterol per day. The best tool for helping type I individuals achieve these objectives is the Exchange Lists for Meal Planning. A second important dietary goal in type I diabetes is to avoid weight gain during intensive treatment programs. The most important dietary and therapeutic goal in obese persons with type II diabetes is weight loss. Unfortunately, no dietary method, whether initiated by self-help groups like TOPS, physicians, or other health care professionals, has been demonstrated to be effective in achieving and maintaining weight loss. Nevertheless, some individual patients will be successful, and it therefore is appropriate to attempt weight reduction with a balanced diet moderately restricted in calories. A reduction of 500 calories per day below the weight maintenance level is reasonable and can be expected to produce weight loss of about 1 lb per week. For those type II diabetic patients who are not able to lose weight and are at least twice their ideal body weight, gastric reduction surgery could be considered. The Glycemic Index of Foods is a new concept that has not been evaluated adequately. Recent evidence suggests that differences among foods are reduced when the foods are combined in a meal and thus raises questions about the utility of glycemic indexing. The longstanding restriction on the use of sucrose in the diabetic diet is without scientific basis. Recognizing this, the American Diabetes Association recently sanctioned consumption of modest amounts of sucrose in the diabetic diet. Although conclusive evidence is not yet available that high fiber diets improve glycemic control or reduce serum lipids in diabetic persons, it appears reasonable to encourage the consumption of natural foods high in soluble fiber. Vegetables (particularly legumes), oats, and many fruits are good sources. The American Diabetes Association recommends a goal of 40 g of soluble fiber intake per day. The dietary treatment of diabetes is likely to be more successful if physicians learn more about its essential features and pay it greater attention. The goals of dietary therapy are difficult to achieve and often require significant sacrifices.(ABSTRACT TRUNCATED AT 400 WORDS)

Long-term effects of guar gum and microcrystalline cellulose on glycaemic control and serum lipids in type 2 diabetes

The effects of guar gum (GG) and microcrystalline cellulose (MC) on metabolic control and serum lipids were compared in a double-blind, cross-over trial in 18 poorly controlled Type 2 diabetic patients. There were two 12 week treatment periods separated by a 4 week wash-out period. A significant reduction in fasting BG was found after 6 weeks treatment with GG, but the initial level was regained after further 6 weeks, at the end of the treatment period. No statistically significant change in fasting BG was observed with MC. Serum cholesterol was lowered by 10% during GG treatment. Microcrystalline cellulose had no effect on serum lipids. The results suggest, that during 12 weeks supplementation with guar gum, the improvement in glycemic control was not sustained, but that it might reduce the risk of macrovascular disease in diabetic patients.