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

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 lipid profile in adults: a GRADE-assessed systematic review, meta-regression and dose-response meta-analysis of randomised placebo-controlled trials

Recent meta-analytic work indicated that guar gum supplementation might improve lipid profile markers in different populations. However, critical methodological limitations such as the use of some unreliable data and the lack of inclusion of several relevant studies, and the scarcity in assessments of regression and dose-specific effects make it difficult to draw meaningful conclusions from the meta-analysis. Therefore, current evidence regarding the effects of guar gum supplementation on lipid profile remains unclear. The present systematic review, meta-regression and dose-response meta-analysis aimed to examine the effects of guar gum supplementation on lipid profile (total cholesterol (TC), LDL, TAG and HDL) in adults. Relevant studies were obtained by searching the PubMed, SCOPUS, Embase and Web of Science databases (from inception to September 2021). Weighted mean differences (WMD) and 95 % CI were estimated via a random-effects model. Heterogeneity, sensitivity analysis and publication bias were reported using standard methods. Pooled analysis of nineteen randomised controlled trials (RCT) revealed that guar gum supplementation led to significant reductions in TC (WMD: -19·34 mg/dl, 95 % CI -26·18, -12·49, P < 0·001) and LDL (WMD: -16·19 mg/dl, 95 % CI -25·54, -6·83, P = 0·001). However, there was no effect on TAG and HDL among adults in comparison with control group. Our outcomes suggest that guar gum supplementation lowers TC and LDL in adults. Future large RCT on various populations are needed to show further beneficial effects of guar gum supplementation on lipid profile and establish guidelines for clinical practice.

Guar gum-based nanoformulations: Implications for improving drug delivery

Poorly soluble drugs are reported to easily degrade in the gastrointestinal tract and contribute in limiting the effect of drug to its targeted site. Oral administration of drug is one of the prominent ways to deliver a drug, although, it experiences barriers like acidic pH, presence of microflora and enzymes in the gastrointestinal tract. Collectively all of these participate in the degradation of drug before it reaches its target site and thus, they impede the sustained effect of drug. A quest of choosing a polymer with good stability profile and releasing the drug to its targeted site is always been a challenge for the scientists worldwide. Many polymers have been reported to prevent the degradation of drug and one such naturally occurring biocompatible polymer is guar gum. Guar gum-based nanoformulations have been extensively used in past decades to achieve controlled drug release which defines its importance. The coating of guar gum over the drug improves the bioavailability of the drug and thus helps in minimizing the risk of drug degradation. This review intends to highlight the beneficial role of guar gum-based nanoformulations to improve drug delivery by ameliorating the bioavailibility.

Galactomannans are the most effective soluble dietary fibers in type 2 diabetes: a systematic review and network meta-analysis

BACKGROUND

Soluble dietary fibers are known to reduce the levels of blood glucose and lipids in patients with type 2 diabetes mellitus (type 2 diabetes). Although several different dietary fiber supplements are utilized, to our knowledge, no previous study has ranked their efficacy yet.

OBJECTIVES

We performed this systematic review and network meta-analysis to rank the effects of different types of soluble dietary fibers.

METHODS

We performed our last systematic search on November 20, 2022. Eligible randomized controlled trials (RCTs) included adult patients with type 2 diabetes and compared the intake of soluble dietary fibers with that of another type of dietary fiber or no fiber. The outcomes were related to glycemic and lipid levels. The Bayesian method was used to perform a network meta-analysis and calculate the surface under the cumulative ranking (SUCRA) curve values to rank the interventions. The Grading of Recommendations Assessment, Development, and Evaluation system was applied to evaluate the overall quality of the evidence.

RESULTS

We identified 46 RCTs, including data from 2685 patients who received 16 types of dietary fibers as intervention. Galactomannans had the highest effect on reducing the levels of HbA1c (SUCRA: 92.33%) and fasting blood glucose (SUCRA: 85.92%). With regard to fasting insulin level, HOMA-IR, β-glucans (SUCRA: 73.45%), and psyllium (SUCRA: 96.67%) were the most effective interventions. Galactomannans were ranked first in reducing the levels of triglycerides (SUCRA: 82.77%) and LDL cholesterol (SUCRA: 86.56%). With regard to cholesterol and HDL cholesterol levels, xylo-oligosaccharides (SUCRA: 84.59%) and gum arabic (SUCRA: 89.06%) were the most effective fibers. Most comparisons had a low or moderate certainty of evidence.

CONCLUSIONS

Galactomannans were the most effective dietary fiber for reducing the levels of HbA1c, fasting blood glucose, triglycerides, and LDL cholesterol in patients with type 2 diabetes. This study was registered at PROSPERO as ID CRD42021282984.

Higher intake of microbiota-accessible carbohydrates and improved cardiometabolic risk factors: a meta-analysis and umbrella review of dietary management in patients with type 2 diabetes

BACKGROUND

Microbiota-accessible carbohydrates (MACs) are critical substrates for intestinal microbes; the subsequent production of SCFAs may have some potential benefits for patients with type 2 diabetes mellitus (T2DM).

OBJECTIVES

We conducted a meta-analysis of randomized controlled trials (RCTs) to assess the effects of higher compared with lower MAC intakes on cardiovascular risk factors in T2DM patients and performed an umbrella review of RCTs to evaluate the evidence quality concerning existing dietary T2DM interventions.

METHODS

Publications were identified by searching MEDLINE, EMBASE, and CINAHL. In the meta-analysis, random-effects models were used to calculate pooled estimates, and sensitivity analyses, meta-regression, subgroup analyses, and Egger's test were performed. For the umbrella review, we summarized pooled estimates, 95% CIs, heterogeneity, and publication bias. The Grading of Recommendations Assessment, Development and Evaluation (GRADE) and modified NutriGrade were used to assess the quality of evidence in the meta-analysis and umbrella review, respectively.

RESULTS

Forty-five RCTs with 1995 participants were included in the meta-analysis. High MAC intake significantly reduced glycated hemoglobin (HbA1c) (weighted mean difference [WMD] -0.436% [-0.556, -0.315]), fasting glucose (WMD -0.835 mmol/L [-1.048, -0.622]), total cholesterol (WMD -0.293 mmol/L [-0.397, -0.190]), triglycerides (WMD -0.118 mmol/L [-0.308, -0.058]), BMI (WMD -0.476 [-0.641, -0.312]), and systolic blood pressure (WMD -3.066 mmHg [-5.653, -0.478]), with a moderate-to-high quality of evidence, compared with low intake. Region, dose, and MAC type were key variables. The umbrella review of all dietary interventions for cardiovascular risk factors in patients with T2DM included 26 meta-analyses with 158 pooled estimates. The evidence quality of MACs, dietary fiber, high-protein diet, ω-3 (n-3), viscous fiber, vitamin D, and vitamin E intake was moderate to high.

CONCLUSIONS

When compared with lower intake, increased MAC intake improved glycemic control, blood lipid, body weight, and inflammatory markers for people with T2DM. This trial was registered at PROSPERO (https://www.crd.york.ac.uk/PROSPERO/#recordDetails) as CRD42019120531.

Carbohydrates: Separating fact from fiction

The role of carbohydrate in a healthy diet has been controversial. The confusion over carbohydrate has come from the long standing limitation of dietary recall studies as well as inability in many of these studies to delineate between the different types of carbohydrates. It is the aim of this paper, to understand and review the data on the role of carbohydrate as pertaining to weight, insulin resistance, diabetes, inflammation, lipids, as well as epidemiological data on long-term cardiovascular outcome and all-cause mortality. We have reviewed the latest epidemiological and intervention studies on fiber, whole grain, and refined carbohydrates on weight, diabetes, lipids as well as major adverse cardiac events that we deemed were scientifically rigorous. High intakes of dietary fiber and whole grains are associated with positive effects on metabolic health while diet high in sugar and refined carbohydrates have negative effects on cardiometabolic health. Consistent evidence indicates that low fat and low carbohydrate diets at comparable energy levels have similar effects on body weight. Large epidemiological studies show when carbohydrates are substituted for animal-derived fat or protein mortality increased while carbohydrate exchanged with plant based protein was associated with mortality reduction. Types of carbohydrate appear to be critical for mortality and cardiovascular events. Evidence shows that quality of the carbohydrate determine cardiometabolic health and cardiovascular events. Given that most people worldwide currently consume less than 20 g of dietary fiber per day with persistently high consumption of refined carbohydrates, current evidence emphasize the need for additional measures to increase the amount and the diversity of fiber intake for improvement of cardiometabolic and cardiovascular outcomes.

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.

Dietary fibre and whole grains in diabetes management: Systematic review and meta-analyses

BACKGROUND

Fibre is promoted as part of a healthy dietary pattern and in diabetes management. We have considered the role of high-fibre diets on mortality and increasing fibre intake on glycaemic control and other cardiometabolic risk factors of adults with prediabetes or diabetes.

METHODS AND FINDINGS

We conducted a systematic review of published literature to identify prospective studies or controlled trials that have examined the effects of a higher fibre intake without additional dietary or other lifestyle modification in adults with prediabetes, gestational diabetes, type 1 diabetes, and type 2 diabetes. Meta-analyses were undertaken to determine the effects of higher fibre intake on all-cause and cardiovascular mortality and increasing fibre intake on glycaemic control and a range of cardiometabolic risk factors. For trials, meta regression analyses identified further variables that influenced the pooled findings. Dose response testing was undertaken; Grading of Recommendations Assessment, Development and Evaluation (GRADE) protocols were followed to assess the quality of evidence. Two multicountry cohorts of 8,300 adults with type 1 or type 2 diabetes followed on average for 8.8 years and 42 trials including 1,789 adults with prediabetes, type 1, or type 2 diabetes were identified. Prospective cohort data indicate an absolute reduction of 14 fewer deaths (95% confidence interval (CI) 4-19) per 1,000 participants over the study duration, when comparing a daily dietary fibre intake of 35 g with the average intake of 19 g, with a clear dose response relationship apparent. Increased fibre intakes reduced glycated haemoglobin (HbA1c; mean difference [MD] -2.00 mmol/mol, 95% CI -3.30 to -0.71 from 33 trials), fasting plasma glucose (MD -0.56 mmol/L, 95% CI -0.73 to -0.38 from 34 trials), insulin (standardised mean difference [SMD] -2.03, 95% CI -2.92 to -1.13 from 19 trials), homeostatic model assessment of insulin resistance (HOMA IR; MD -1.24 mg/dL, 95% CI -1.72 to -0.76 from 9 trials), total cholesterol (MD -0.34 mmol/L, 95% CI -0.46 to -0.22 from 27 trials), low-density lipoprotein (LDL) cholesterol (MD -0.17 mmol/L, 95% CI -0.27 to -0.08 from 21 trials), triglycerides (MD -0.16 mmol/L, 95% CI -0.23 to -0.09 from 28 trials), body weight (MD -0.56 kg, 95% CI -0.98 to -0.13 from 18 trials), Body Mass Index (BMI; MD -0.36, 95% CI -0·55 to -0·16 from 14 trials), and C-reactive protein (SMD -2.80, 95% CI -4.52 to -1.09 from 7 trials) when compared with lower fibre diets. All trial analyses were subject to high heterogeneity. Key variables beyond increasing fibre intake were the fibre intake at baseline, the global region where the trials were conducted, and participant inclusion criteria other than diabetes type. Potential limitations were the lack of prospective cohort data in non-European countries and the lack of long-term (12 months or greater) controlled trials of increasing fibre intakes in adults with diabetes.

CONCLUSIONS

Higher-fibre diets are an important component of diabetes management, resulting in improvements in measures of glycaemic control, blood lipids, body weight, and inflammation, as well as a reduction in premature mortality. These benefits were not confined to any fibre type or to any type of diabetes and were apparent across the range of intakes, although greater improvements in glycaemic control were observed for those moving from low to moderate or high intakes. Based on these findings, increasing daily fibre intake by 15 g or to 35 g might be a reasonable target that would be expected to reduce risk of premature mortality in adults with diabetes.

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.

Gastrointestinal Transit Time, Glucose Homeostasis and Metabolic Health: Modulation by Dietary Fibers

Gastrointestinal transit time may be an important determinant of glucose homeostasis and metabolic health through effects on nutrient absorption and microbial composition, among other mechanisms. Modulation of gastrointestinal transit may be one of the mechanisms underlying the beneficial health effects of dietary fibers. These effects include improved glucose homeostasis and a reduced risk of developing metabolic diseases such as obesity and type 2 diabetes mellitus. In this review, we first discuss the regulation of gastric emptying rate, small intestinal transit and colonic transit as well as their relation to glucose homeostasis and metabolic health. Subsequently, we briefly address the reported health effects of different dietary fibers and discuss to what extent the fiber-induced health benefits may be mediated through modulation of gastrointestinal transit.

Re-evaluation of celluloses E 460(i), E 460(ii), E 461, E 462, E 463, E 464, E 465, E 466, E 468 and E 469 as food additives

Following a request from the European Commission, the EFSA Panel on Food Additives and Nutrient Sources added to Food (ANS) was asked to deliver a scientific opinion re-evaluating the safety of microcrystalline cellulose (E 460(i)), powdered cellulose (E 460(ii)), methyl cellulose (E 461), ethyl cellulose (E 462), hydroxypropyl cellulose (E 463), hydroxypropyl methyl cellulose (E 464), ethyl methyl cellulose (E 465), sodium carboxy methyl cellulose (E 466), enzymatically hydrolysed carboxy methyl cellulose (E 469) and cross-linked carboxy methyl cellulose (E 468) as food additives. The Joint FAO/WHO Expert Committee on Food Additives (JECFA) and the Scientific Committee on Food (SCF) established an acceptable daily intake (ADI) 'not specified' for unmodified and modified celluloses. Celluloses are not absorbed and are excreted intact in the faeces; in addition, microcrystalline cellulose, powdered and modified celluloses could be fermented by the intestinal flora in animals and humans. Specific toxicity data were not always available for all the celluloses evaluated in the present opinion and for all endpoints. Given their structural, physicochemical and biological similarities, the Panel considered it possible to read-across between all the celluloses. The acute toxicity of celluloses was low and there was no genotoxic concern. Short-term and subchronic dietary toxicity studies performed with E 460(i), E 461, E 462, E 463, E 464, E 466 and E 469 at levels up to 10% did not indicate specific treatment related adverse effects. In chronic toxicity studies performed with E 460(i), E 461, E 463, E 464, E 465 and E 466, the no observed adverse effect level (NOAEL) values reported ranged up to 9,000 mg/kg body weight (bw) per day. No carcinogenic properties were detected for microcrystalline cellulose and modified celluloses. Adverse effects on reproductive performance or developmental effects were not observed with celluloses at doses greater than 1,000 mg/kg bw by gavage (often the highest dose tested). The combined exposure to celluloses (E 460-466, E 468 and E 469) at 95th percentile of the refined (brand-loyal) exposure assessment for the general population was up to 506 mg/kg bw per day. The Panel concluded that there was no need for a numerical ADI and that there would be no safety concern at the reported uses and use levels for the unmodified and modified celluloses (E 460(i); E 460(ii); E 461-466; E 468 and E 469). The Panel considered an indicative total exposure of around 660-900 mg/kg bw per day for microcrystalline, powdered and modified celluloses.

Functionality and nutritional aspects of microcrystalline cellulose in food

Microcrystalline cellulose (MCC) is among the most commonly used cellulose derivatives in the food industry. In order assess the recent advances of MCC in food product development and its associated nutraceutical implications, google scholar and database of journals subscribed by Jiangnan university, China were used to source literature. Recently published research articles that reported physicochemical properties of MCC for food application or potential application in food and nutraceutical functions were reviewed and major findings outlined. The selected literature reviewed demonstrated that the material has been extensively explored as a functional ingredient in food including meat products, emulsions, beverages, dairy products, bakery, confectionary and filling. The carbohydrate polymer also has many promising applications in functional and nutraceutical food industries. Though widely used as control for many dietary fiber investigations, MCC has been shown to provide positive effects on gastrointestinal physiology, and hypolipidemic effects, influencing the expression of enzymes involved in lipid metabolism. These techno-functional and nutraceutical properties of MCC are influenced by the physicochemical of the material, which are defined by the raw material source and processing conditions. Apart from these functional properties, this review also highlighted limitations and gaps regarding the application of material in food and nutritional realms. Functional, Nutritional and health claims of MCC.

Improvement of the metabolic syndrome profile by soluble fibre - guar gum - in patients with type 2 diabetes: a randomised clinical trial

A diet rich in fibre seems to protect against the metabolic syndrome (MetS), but there is scarce information about the role of fibre intake in patients with the MetS and diabetes. The aim of the present study was to evaluate the effects of soluble fibre from partially hydrolysed guar gum (PHGG) on the MetS and cardiovascular risk factors in patients with type 2 diabetes. In the present randomised controlled clinical trial, forty-four patients with type 2 diabetes (males 38·6 %, age 62 (SD 9) years, diabetes duration 14·2 (SD 9·6) years) and the MetS underwent clinical, laboratory and dietary evaluations at baseline, 4 and 6 weeks. All patients followed their usual diet and the intervention group (n 23) received an additional 10 g/d of PHGG. In the intervention group, waist circumference (WC), glycated Hb (HbA1c), 24 h urinary albumin excretion (UAE) and serum trans-fatty acids (FA) were reduced in comparison with baseline after 4 and 6 weeks: WC 103·5 (SD 9·5) to 102·1 (SD 10) to 102·3 (SD 9·7) cm; HbA1c 6·88 (SD 0·99) to 6·64 (SD 0·94) to 6·57 (SD 0·84) %; 24 h UAE 6·8 (interquartile range 3·0-17·5) to 4·5 (interquartile range 3·0-10·5) to 6·2 (interquartile range 3·0-9·5) mg; trans-FA 71 (interquartile range 46-137) to 67 (interquartile range 48-98) to 57 (interquartile range 30-110) mg/l (P< 0·05 for all). The only change in the control group was weight reduction: 77·0 (SD 13·5) to 76·2 (SD 13·3) to 76·1 (SD 13·4) kg (P= 0·005). Other MetS components (blood pressure, TAG, HDL-cholesterol, fasting plasma glucose), total and LDL-cholesterol, C-reactive protein and endothelin-1 did not change in either group. In patients with type 2 diabetes and the MetS, the addition of PHGG to the usual diet improved cardiovascular and metabolic profiles by reducing WC, HbA1c, UAE and trans-FA.

Do Sugar Substitutes Have Any Impact on Glycemic Control in Patients with Diabetes?

Objective:

To evaluate the impact of nonnutritive sugar substitutes on glycemic control in patients with diabetes.

Data Sources:

A comprehensive review of the literature was conducted in PubMed (1966-March 2012) and Scopus. A combination of MeSH terms and keywords were used, including acesulfame, aspartame, diabetes, neotame, rebiana, saccharin, stevia, and sucralose.

Study Selection and Data Extraction:

Clinical studies evaluating the impact of nonnutritive sweeteners on measures of diabetic control, including, but not limited to, blood glucose levels, postprandial blood glucose, and hemoglobin A1c were selected for review. Searches were limited to only nonnutritive sweeteners available in the US.

Data Synthesis:

Nine clinical trials that evaluated nonnutritive sweeteners in a total of 490 patients with diabetes were found. Doses of sweeteners in the studies varied from below acceptable daily intake levels for 3 consecutive days to daily dosing for up to 18 weeks and up to 3.5 times the acceptable daily intake levels. No significant differences in overall effects on glycemic control and insulin response were found.

Conclusions:

Nonnutritive sweeteners do not appear to affect glycemic control in patients with diabetes. Patients should be counseled to maintain an appropriate energy balance in their diet, with or without the use of nonnutritive sweeteners.

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.

Dietary fiber improves lipid homeostasis and modulates adipocytokines in hamsters

BACKGROUND

The hypocholesterolemic and hypoglycemic effects of various natural and semisynthetic dietary fibers have been studied for their potential use in the prevention and improvement of metabolic syndrome. Of these dietary fibers, hydroxypropyl methylcellulose (HPMC) has been shown to lower plasma cholesterol and reduce weight gain. However, the underlying mechanisms are not known. In the present study, we examined associations between plasma adipocytokine levels and both lipid metabolism and insulin sensitivity after HPMC intake in golden Syrian hamsters. In addition, endogenous adiponectin from hamster plasma was purified and characterized.

METHODS

Hamsters were treated with HPMC (2% and 4% in a high-fat diet) or 2% or 4% microcrystalline cellulose (MCC; control diet) for 8 weeks. Plasma glucose, insulin, lipids, adiponectin, leptin, and hepatic lipid levels were assessed using standard techniques.

RESULTS

After 8 weeks of feeding, plasma total cholesterol and triglyceride levels in hamsters fed the 4% HPMC-supplemented diet were significantly lower than in hamsters fed the control diet. Moreover, a significant increase in adiponectin levels and a decrease in leptin levels were observed in hamsters fed the 4% HPMC-supplemented diet. Hamster adiponectin was found to be comprised of 244 amino acid residues with an apparent molecular weight of 30 kDa, consistent with the adiponectin reported in other species.

CONCLUSIONS

Reductions in plasma cholesterol and triglyceride levels were correlated with a decrease in plasma leptin and an increase in adiponectin. These results suggest that adipocytokines are regulated by HPMC and may play a pivotal role in the hypocholesterolemic effect.

Guar Gum: A Miracle Therapy for Hypercholesterolemia, Hyperglycemia and Obesity

The number of hypercholesterolemic and hyperglycemic people is increasing rapidly in the world. The prevention against these health problems is related to a complex management of conventional and non-conventional risk factors. The inclusion of dietary fiber in the diet is the right approach to reduce these risks. Cholesterol and glucose lowering effects are most often associated with gelling, mucilaginous, and viscous fibers such as guar gum, an edible thickening agent. It has widespread applications in the food industry due to its ability to hydrate without heating. The demand for guar gum is still growing rapidly because in addition to its indispensable role in lowering serum cholesterol and glucose levels, it is also considered helpful in weight loss programs. The main thrust of therapeutic and medicinal properties lies in the soluble dietary fiber content of guar gum to improve the serum biochemical profile of human and non-human primates, reducing total serum cholesterol, triglycerides, increasing the high density lipoprotein cholesterol level, and the management of glycemic indices and obesity. Among the various intervention strategies, diet diversification is the right approach to overcome these problems. Composite flours containing wheat and legumes have proven practical uses and are being utilized in many parts of the world to improve the nutritional and functional properties of flour. The main focus of this manuscript is to review the available information on various aspects of guar gum with special reference to its effectiveness in reducing the cardiovascular disease risk, diabetes and weight loss programs.

Guar gum for body weight reduction: meta-analysis of randomized trials

PURPOSE

To determine the efficacy of the dietary fiber guar gum as a therapeutic option for reducing body weight by conducting a meta-analysis of randomized controlled trials.

METHODS

Literature searches were performed on the electronic databases Medline, Embase, Biosis, Amed, and the Cochrane Library. Manufacturers of commercial guar gum preparations and experts on the subject were contacted to provide any published or unpublished trials. For inclusion, trials had to state that they were randomized, double blinded, and placebo controlled, used guar gum monopreparations, and reported body weight as an endpoint. No language restrictions were imposed. Two reviewers independently extracted data in a standardized manner according to predefined criteria and evaluated methodological quality using the scoring system developed by Jadad. Discrepancies were settled through discussion.

RESULTS

Thirty-four trials were identified and 20 could be included. Eleven trials provided data that were suitable for statistical pooling. The meta-analysis indicated a nonsignificant difference in patients receiving guar gum compared with patients receiving placebo (weighted mean difference -0.04 kg; 95% confidence interval (CI): -2.2 to 2.1). Analysis of six trials with similar methodologic features corroborates these findings (weighted mean difference -0.3 kg; 95% CI: -4.0 to 3.5). Adverse events most frequently reported were abdominal pain, flatulence, diarrhea, and cramps. Overall, 11 patients (3%) dropped out owing to adverse events.

CONCLUSIONS

This meta-analysis suggests that guar gum is not efficacious for reducing body weight. Considering the adverse events associated with its use, the risks of taking guar gum outweigh its benefits for this indication. Therefore, guar gum cannot be recommended as a treatment for lowering body weight.

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.