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

The effect of psyllium on fasting blood sugar, HbA1c, HOMA IR, and insulin control: a GRADE-assessed systematic review and meta-analysis of randomized controlled trials

There is equivocal evidence that psyllium can prevent or attenuate increases in fasting blood sugar. Therefore, this systematic review and meta-analysis sought to investigate the influence of psyllium on hemoglobin A1C (HbA1c), fasting blood sugar (FBS), insulin, and Homeostatic Model Assessment of Insulin Resistance (HOMA IR). We searched PubMed, ISI Web of Science (WOS), and Scopus for eligible publications, up to 15 July 2022, including randomized controlled trials (RCT) assessing the effect of psyllium on HbA1c, FBS, insulin, and HOMA IR levels in adults. Using a random effects model, we report the weighted mean differences (WMD) with 95% confidence intervals (CI). In this article, 19 RCT studies, consisting of 962 participants, were included. Psyllium significantly decreased FBS, HbA1c, and HOMA IR levels, but not insulin levels, as compared to placebo (FBS: WMD): -6.89; 95% CI: -10.62, -3.16; p < .001), HbA1c: (WMD: -0.75; 95% CI: -1.21, -0.29; p < .001), HOMA IR: (WMD: -1.17; 95% CI: -2.11, -0.23; p < .05), and insulin: (WMD: -2.08; 95% CI: -4.21, -0.035; p > .05)). Subgroup analyses illustrated differences in the effects of psyllium on FBS: dosages less than and more than 10 g/d showed significant differences (p value < 0.05). However, it was not significant in intervention durations less than 50 days (p value > 0.05). For HbA1c: psyllium consumption less than 10 g/d (p value > 0.05) was non-significant. For HOMA IR and insulin: no significant changes were noted with psyllium consumption less than vs. more than 10 g/d. In conclusion, we found that psyllium could significantly decrease FBS, HbA1c, and HOMA IR levels, but not insulin levels, as compared to placebo.

Dietary supplements: clinical cholesterol-lowering efficacy and potential mechanisms of action

This review aims to analyse the efficacy of dietary supplements in reducing plasma cholesterol levels. Focusing on evidence from meta-analyses of randomised controlled clinical trials, with an emphasis on potential mechanisms of action as supported by human, animal, and cell studies. Certain dietary supplements including phytosterols, berberine, viscous soluble dietary fibres, garlic supplements, soy protein, specific probiotic strains, and certain polyphenol extracts could significantly reduce plasma total and low-density lipoprotein (LDL) cholesterol levels by 3-25% in hypercholesterolemic patients depending on the type of supplement. They tended to be more effective in reducing plasma LDL cholesterol level in hypercholesterolemic individuals than in normocholesterolemic individuals. These supplements worked by various mechanisms, such as enhancing the excretion of bile acids, inhibiting the absorption of cholesterol in the intestines, increasing the expression of hepatic LDL receptors, suppressing the activity of enzymes involved in cholesterol synthesis, and activating the adenosine monophosphate-activated protein kinase signalling pathway.

No benefit of soluble fiber on liver function

Background: To conduct a systematic review and dose-response meta-analysis of current findings from randomized controlled trials (RCTs) on the effect of soluble fiber supplementation on liver function in both healthy individuals and people with specific health conditions, PubMed, Scopus, and ISI Web of Science were systematically searched for relevant RCTs published prior to April 2022. Methods: We estimated the change in liver function parameters for each 5 g/d increment in soluble fiber in each trial and then calculated the mean difference (MD) and 95%CI. A total of 25 RCTs with 27 treatment arms (1744 subjects; 884 cases, 860 controls) were included. Results: A total of 25 RCTs with 27 treatment arms were included. The intervention duration of the included studies ranged from 3 to 52 weeks and the dose of soluble fiber supplementation varied from 0.0025 to 40 g/d. Soluble fiber supplementation could not significantly affect serum alanine transaminase (MD: -0.02 U/L, 95% CI: -1.06 to 1.01), aspartate transaminase (MD: -0.34 U/L, 95% CI: -0.84 to 0.15), alkaline phosphatase (MD: 0.29 U/L, -0.14 to 0.71), gamma-glutamyl transferase (MD: 0.12 U/L; 95% CI: -0.81 to 1.05), serum bilirubin (MD: 0.42μmol/L, 95% CI: -0.08 to 0.93) and albumin (MD: 0.64 g/dl, 95% CI: -0.42 to 1.70) levels. Conclusions: Findings from this study did not support the beneficial effects of soluble fiber supplementation on liver function biomarkers. There is a need for long-term high-quality interventions to examine the effects of different types and doses of soluble fibers on liver function as primary outcome.

Impact of fibre supplementation on microbiome and resilience in healthy participants: A randomized, placebo-controlled clinical trial

BACKGROUND AND AIMS

The gut microbiome exerts important roles in health, e.g., functions in metabolism and immunology. These functions are often exerted via short-chain fatty acid (SCFA) production by gut bacteria. Studies demonstrating causal relationships between interventions targeting the microbiome and clinical outcomes are limited. This study aimed to show a causal relationship between microbiome modulation through fibre intervention and health.

METHODS AND RESULTS

This randomized, double-blind, cross-over study included 65 healthy subjects, aged 45-70 years, with increased metabolic risk (i.e., body mass index [BMI] 25-30 kg/m2, low to moderate daily dietary fibre intake, <30g/day). Subjects took daily a fibre mixture of Acacia gum and carrot powder or placebo for 12 weeks, with an 8-week wash-out period. Faecal samples for measurement of SCFAs and microbiome analysis were collected every 4 weeks. Before and after each intervention period subjects underwent the mixed-meal PhenFlex challenge Test (PFT). Health effects were expressed as resilience to the stressors of the PFT and as fasting metabolic and inflammatory state. The fibre mixture exerted microbiome modulation, with an increase in β-diversity (p < 0.001). α-diversity was lower during fibre mixture intake compared to placebo after 4, 8 and 12 weeks (p = 0.002; p = 0.012; p = 0.031). There was no effect observed on faecal SCFA concentrations, nor on any of the primary clinical outcomes (Inflammatory resilience: p = 0.605, Metabolic resilience: p = 0.485).

CONCLUSION

Although the intervention exerted effects on gut microbiome composition, no effects on SCFA production, on resilience or fasting metabolic and inflammatory state were observed in this cohort. REGISTRATION NUMBER CLINICALTRIALS.GOV: NCT04829396.

Association between dietary fiber intake and diabetic nephropathy among adult diabetes mellitus in the United States: A cross-sectional study

Objective

There has been some evidence that dietary fiber may be associated with diabetic nephropathy (DN), but the relationship is still unclear. The purpose of this study was to examine the association between dietary fiber intake and DN.

Methods

This cross-sectional study used National Health and Nutrition Examination Survey (NHANES) data collected between 2007 and 2020. Weighted multivariate logistic regression was used to examine the relation between dietary fiber intake and DN. In addition, fitted smoothed curves were used to explore potential non-linear relationships. If non-linearity was observed, inflection points were further calculated by a recursive algorithm.

Results

The study finally included 5964 subjects ≥20 years of age. The mean age was 60.8 ± 13.4 years with males (52.4 %), and non-Hispanic Whites (62.4 %), and the weighted prevalence of DN was 36.7 %. Dietary fiber was negatively associated with the risk of DN after controlling for all confounding variables (OR = 0.89, 95%CI: 0.80, 0.99). Smoothed curve fit plots of the dose relationship showed that dietary fiber intake was linearly related to DN, whereas males (inflection point of 8.0 g/d) and non-Hispanic Blacks (inflection point of 14.9 g/d) followed a non-linear inverted U-shaped curve relationship. In United States adults aged 20 and older, dietary fiber intake may be associated with a reduced risk of DN.

Conclusion

Appropriate increases in dietary fiber intake may offer potential benefits for DN. In conclusion, it appears that increasing dietary fiber intake may be one of the most effective strategies for the prevention and management of DN.

Validation of Nutritional Approaches to Modulate Cardiovascular and Diabetic Risk Factors in Patients with Hypertriglyceridemia or Prediabetes-The MoKaRi II Randomized Controlled Study

Hypertriglyceridemia and diabetes mellitus type 2 are among the most important metabolic diseases globally. Diet plays a vital role in the development and progression of both clinical pictures. For the 10-week randomized, controlled, intervention study, 67 subjects with elevated plasma triglyceride (TG) concentrations (≥1.7 mmol/L) and 69 subjects with elevated fasting glucose concentrations (≥5.6 < 7.0 mmol/L) were recruited. The intervention groups received specially developed, individualized menu plans and regular counseling sessions to lower (A) TG or (B) fasting glucose and glycated hemoglobin A1c as well as other cardiovascular and diabetic risk factors. The hypertriglyceridemia intervention group was further supplemented with fish oil (3.5 g/d eicosapentaenoic acid + docosahexaenoic acid). The two control groups maintained a typical Western diet. Blood samples were taken every 2 weeks, and anthropometric data were collected. A follow-up examination was conducted after another 10 weeks. In both intervention groups, there were comparable significant reductions in blood lipids, glucose metabolism, and anthropometric parameters. These results were, with a few exceptions, significantly more pronounced in the intervention groups than in the corresponding control groups (comparison of percentage change from baseline). In particular, body weight was reduced by 7.4% (6.4 kg) and 7.5% (5.9 kg), low-density lipoprotein cholesterol concentrations by 19.8% (0.8 mmol/L) and 13.0% (0.5 mmol/L), TG concentrations by 18.2% (0.3 mmol/L) and 13.0% (0.2 mmol/L), and homeostatic model assessment for insulin resistance by 31.8% (1.1) and 26.4% (0.9) (p < 0.05) in the hypertriglyceridemia and prediabetes intervention groups, respectively. Some of these changes were maintained until follow-up. In patients with elevated TG or fasting glucose, implementing individualized menu plans in combination with regular counseling sessions over 10 weeks led to a significant improvement in cardiovascular and diabetic risk factors.

Nutrient quality in dietary therapy for diabetes and diabetic kidney disease

Dietary therapy is crucial for diabetes care with the aim of preventing the onset and progression of diabetes and its complications. The traditional approach to dietary therapy for diabetes has primarily focused on restricting the intake of the three major nutrients and rigorously controlling blood glucose levels. However, advancements in nutritional science have shown that within the three major nutrients - carbohydrates, proteins and lipids - there exist multiple types, each with distinct impacts on type 2 diabetes and its complications, sometimes even showing conflicting effects. In light of this, the present review shifts its focus from the quantity to the quality of the three major nutrients. It aims to provide an overview of how the differences in nutrient quality can influence onset and progression of type 2 diabetes and diabetic kidney disease, highlighting the diverse effects and, at times, contradictory impacts associated with each nutrient type.

Dietary fiber intake and its association with diabetic kidney disease in American adults with diabetes: A cross-sectional study

BACKGROUND

Dietary fiber (DF) intake may have a protective effect against type 2 diabetes (T2D); however, its relationship with diabetic kidney disease (DKD) remains unclear.

AIM

To investigate the potential association between DF intake and the prevalence of DKD in individuals diagnosed with T2D.

METHODS

This cross-sectional study used data from the National Health and Nutrition Examination Survey collected between 2005 and 2018. DF intake was assessed through 24-h dietary recall interviews, and DKD diagnosis in individuals with T2D was based on predefined criteria, including albuminuria, impaired glomerular filtration rate, or a combination of both. Logistic regression analysis was used to assess the association between DF intake and DKD, and comprehensive subgroup and sensitivity analyses were performed.

RESULTS

Among the 6032 participants, 38.4% had DKD. With lower DF intake-T1 (≤ 6.4 g/1000 kcal/day)-as a reference, the adjusted odds ratio for DF and DKD for levels T2 (6.5-10.0 g/1000 kcal/day) and T3 (≥ 10.1 g/1000 kcal/day) were 0.97 (95%CI: 0.84-1.12, P = 0.674) and 0.79 (95%CI: 0.68-0.92, P = 0.002), respectively. The subgroup analysis yielded consistent results across various demographic and health-related subgroups, with no statistically significant interactions (all P > 0.05).

CONCLUSION

In United States adults with T2D, increased DF intake may be related to reduced DKD incidence. Further research is required to confirm these findings.

Nutritional Aspects to Cardiovascular Diseases and Type 2 Diabetes Mellitus

PURPOSE OF REVIEW

In this narrative review, we discuss the current evidence related to the role of dietary interventions to prevent and treat type 2 diabetes mellitus (T2DM) and cardiovascular disease (CVD). We also propose alternative therapeutic strategies other than weight loss in this population, namely, improvements in cardiorespiratory fitness and its determinants.

RECENT FINDINGS

While weight loss has been consistently associated with the prevention of T2DM and improvements in glycemic control in those with established diseases, its role in preventing and treating CVD is less clear. In fact, in this setting, improvements in diet quality have provided greater benefits, suggesting that this might represent an alternative, or an even more effective strategy than energy-restriction. Improvements in diet quality, with and without caloric restriction have been shown to improve CVD risk and to prevent the development of T2DM in individuals at risk; however, with regard to glycemic control in patients with T2DM, any dietary intervention resulting in significant weight loss may produce clinically meaningful benefits. Finally, dietary interventions with and without energy restriction that can improve cardiorespiratory fitness, even in absence of weight loss in patients with obesity, should be encouraged.

Inulin: Unveiling its potential as a multifaceted biopolymer in prebiotics, drug delivery, and therapeutics

In recent years, inulin has gained much attention as a promising multifunctional natural biopolymer with numerous applications in drug delivery, prebiotics, and therapeutics. It reveals a multifaceted biopolymer with transformative implications by elucidating the intricate interplay between inulin and the host, microbiome, and therapeutic agents. Their flexible structure, exceptional targetability, biocompatibility, inherent ability to control release behavior, tunable degradation kinetics, and protective ability make them outstanding carriers in healthcare and biomedicine. USFDA has approved Inulin as a nutritional dietary supplement for infants. The possible applications of inulin in biomedicine research inspired by nature are presented. The therapeutic potential of inulin goes beyond its role in prebiotics and drug delivery. Recently, significant research efforts have been made towards inulin's anti-inflammatory, antioxidant, and immunomodulatory properties for their potential applications in treating various chronic diseases. Moreover, its ability to reduce inflammation and modulate immune responses opens new avenues for treating conditions such as autoimmune disorders and gastrointestinal ailments. This review will attempt to illustrate the inulin's numerous and interconnected roles, shedding light on its critical contributions to the advancement of healthcare and biomedicine and its recent advancement in therapeutics, and conclude by taking valuable insights into the prospects and opportunities of inulin.

The Effects of L-Carnitine Supplementation on Blood Pressure in Adults: A Systematic Review and Dose-response Meta-analysis

PURPOSE

Hypertension stands as a prominent risk factor for cardiovascular disease, making it of utmost importance to address. Studies have shown that L-carnitine supplementation may lower blood pressure (BP) parameters in different populations. Therefore, we have conducted a systematic review and dose-response meta-analysis of published Randomized Controlled Trials (RCTs), including the most recent articles on the effect of L-carnitine supplementation on BP.

METHODS

PubMed, ISI Web of Science, Cochrane databases, and Scopus were used to collect RCT studies published up to October 2022 without limitations in language. Inclusion criteria were adult participants and recipients of L-carnitine in oral supplemental forms. The funnel plot test, Begg's test, and Egger's test were used to examine publication bias.

FINDINGS

After the search strategy, 22 RCTs (n = 1412) with 24 effect sizes fulfilled the criteria. It was found L-Carnitine supplementation did not have a significant effect on systolic blood pressure (SBP) (mm Hg) (weighted mean difference [WMD] = -1.22 mm Hg, 95% CI: -3.79, 1.35; P = 0.352; I2 = 85.0%, P < 0.001), and diastolic blood pressure (mm Hg) (WMD = -0.50 mm Hg, 95% CI: -1.49, 0.48; P = 0.318; I2 = 43.4%, P = 0.021) in the pooled analysis. Subgroup analyses have shown that L-carnitine supplementation had no lowering effect on SBP in any subgroup. However, there was a significant reduction in diastolic blood pressure in participants with a baseline body mass index >30 kg/m2 (WMD = -1.59 mm Hg; 95% CI: -3.11, -0.06; P = 0.041; I2 = 41.3%, P = 0.164). There was a significant nonlinear relationship between the duration of L-carnitine intervention and changes in SBP (coefficients = -6.83, P = 0.045).

IMPLICATIONS

L-carnitine supplementation in adults did not significantly affect BP. But anyway, more studies should be done in this field on different individuals.

The effect of acarbose on inflammatory cytokines and adipokines in adults: a systematic review and meta-analysis of randomized clinical trials

BACKGROUND

Although a large number of trials have observed an anti-inflammatory property of acarbose, the currently available research remains controversial regarding its beneficial health effects. Hence, the purpose of this study was to examine the effect of acarbose on inflammatory cytokines and adipokines in adults.

METHODS

PubMed, Web of Science, and Scopus were systematically searched until April 2023 using relevant keywords. The mean difference (MD) of any effect was calculated using a random-effects model. Weighted mean difference (WMD) and 95% confidence intervals (CIs) were calculated via the random-effects model.

RESULTS

The current meta-analysis of data comprised a total of 19 RCTs. Meta-analysis showed that acarbose significantly decreased tumor necrosis factor-alpha (TNF-α) (weighted mean difference [WMD]) = - 4.16 pg/ml, 95% confidence interval (CI) - 6.58, - 1.74; P = 0.001) while increasing adiponectin (WMD = 0.79 ng/ml, 95% CI 0.02, 1.55; P = 0.044). However, the effects of acarbose on TNF-α concentrations were observed in studies with intervention doses ≥ 300 mg/d (WMD = - 4.09; 95% CI - 7.00, - 1.18; P = 0.006), and the adiponectin concentrations were significantly higher (WMD = 1.03 ng/ml, 95%CI 0.19, 1.87; P = 0.016) in studies in which the duration of intervention was less than 24 weeks. No significant effect was seen for C-reactive protein (CRP; P = 0.134), interleukin-6 (IL-6; P = 0.204), and leptin (P = 0.576).

CONCLUSION

Acarbose had beneficial effects on reducing inflammation and increasing adiponectin. In this way, it may prevent the development of chronic diseases related to inflammation. However, more studies are needed.

Dietary fiber intake and all-cause and cause-specific mortality: An updated systematic review and meta-analysis of prospective cohort studies

BACKGROUND

Accumulating evidence supports the effects of dietary fiber on the risk of non-communicable diseases (NCDs). However, there is no updated systematic review and meta-analysis that compares and pools the effect of different types of fiber on mortality.

METHODS

In this systematic review and meta-analysis, all prospective cohort studies that evaluated the relationship between dietary fiber intake and all-cause or cause-specific mortality were included. The PubMed, SCOPUS, and Web of Science databases were searched up to October 2022. Data extraction and quality assessment were performed by two researchers independently. Heterogeneity between studies was assessed using Chi-square based test. Random/fixed effect meta-analysis was used to pool the hazard ratios (HR) or relative risks (RR) and 95 % confidence intervals (CI) for the association between different types of fiber and mortality.

RESULTS

This systematic review included 64 eligible studies, with a total sample size of 3512828 subjects, that investigated the association between dietary fiber intake and mortality from all-cause, cardiovascular disease (CVD), and cancer. Random-effect meta-analysis shows that higher consumption of total dietary fiber, significantly decreased the risk of all-cause mortality, CVD-related mortality, and cancer-related mortality by 23, 26 and 22 % (HR:0.77; 95%CI (0.73,0.82), HR:0.74; 95%CI (0.71,0.77) and HR:0.78; 95%CI (0.68,0.87)), respectively. The consumption of insoluble fiber tended to be more effective than soluble fiber intake in reducing the risk of total mortality and mortality due to CVD and cancer. Additionally, dietary fiber from whole grains, cereals, and vegetables was associated with a reduced risk of all-cause mortality, while dietary fiber from nuts and seeds reduced the risk of CVD-related death by 43 % (HR:0.57; 95 % CI (0.38,0.77)).

CONCLUSION

This comprehensive meta-analysis provides additional evidence supporting the protective association between fiber intake and all-cause and cause-specific mortality rates.

Effect of soluble fiber on blood pressure in adults: a systematic review and dose-response meta-analysis of randomized controlled trials

OBJECTIVES

Pervious epidemiologic evidence indicates that soluble fiber is protective against hypertention: however, randomized controlled trials (RCTs) have presented varying results. In the present study, we aimed to conduct a systematic review and dose-response meta-analysis to summarize published RCTs which assess the effect of soluble fiber supplementation on systolic blood pressure (SBP) and diastolic blood pressure (DBP).

METHODS

Scopus, PubMed, and ISI Web of Sciences were searched to identify relevant studies up to Aug 2022. We estimated the change in blood pressure for each 5 g/d increment in soluble fiber supplementation in each trial and then calculated the weighted mean difference (WMD) and 95%CI using a random-effects model. We estimated dose-dependent effects using a dose-response meta-analysis of differences in means. The risk of bias for study was assessed using the Cochrane tool. Publication bias was evaluated via funnel plot and Begg's test and Egger's test.

RESULTS

Eighty-three eligible studies with total sample size of 5,985 participants were included in the meta-analysis. Soluble fiber supplementation significantly decreased SBP (WMD: -1.36 mmHg, 95% CI: -2.13 to -0.60, P < 0.001; I2 = 47.1%, P < 0.001) and DBP (WMD: -0.72 mmHg, 95% CI: -1.26 to -0.18, P = 0.009; I2 = 45.4%, P < 0.001). Each 5 g/d increment in soluble fiber supplementation had a significant reduction in SBP (WMD: -0.54 mmHg; 95%CI: -0.86, -0.22, P = 0.001; I2 = 52.2, Phet < 0.001) and DBP (WMD: -0.28 mmHg; 95%CI: -0.49, -0.80, P = 0.007; I2 = 43.1%, Phet < 0.001). The levels of SBP decreased proportionally with the increase in soluble fiber supplementation up to 20 g/d (MD20g/d: -1.79 mmHg, 95%CI: -2.86, -0.71).

CONCLUSION

Current evidence indicated the beneficial effect of soluble fiber supplementation on blood pressure. Our findings suggest that soluble fiber supplementation could contribute to the management of hypertension and the reduction of cardiovascular disease risk.

Usual dietary fibre intake according to diabetes status in USA adults - NHANES 2013-2018

It is unknown if fibre intake differs across diabetes status in USA adults and is associated with glycaemic outcomes. This cross-sectional analysis utilised National Health and Nutrition Examination Survey cycles 2013-2018 data to estimate usual total dietary fibre intake in USA adults and across diabetes status (no diabetes, prediabetes and type II diabetes (T2D)). Associations among dietary fibre intake and glycaemic outcomes were also reported across groups. Adults (≥ 19 years) with at least one dietary recall were included. Diabetes status was determined from self-report data and measured HbA1c. Independent samples t tests were used to compare mean (se) intake across sub-populations. 14 640 adults (51·3 % female) with 26·4 % and 17·4 % classified as having prediabetes and T2D, respectively. Adults with T2D reported greater mean (se) dietary fibre intake compared with no T2D for females (9·5 (0·13) v. 8·7 (0·11) g/1000 kcal/d and males (8·5 (0·12) v. 7·7 (0·11) g/1000 kcal/d; P < 0·01)). However, only 4·2 (0·50)% and 8·1 (0·90)% of males and females with T2D, respectively, met the adequate intake for fibre. Fibre intake was associated with lower insulin (β = -0·80, P < 0·01), serum glucose (β = -1·35, P < 0·01) and Homeostatic Model Assessment for Insulin Resistance (β = -0·22, P < 0·01) in adults without diabetes, and no relationships in adults with prediabetes or T2D were found. Although dietary fibre intake was highest among adults with T2D, intake was suboptimal across all groups. In adults without diabetes, dietary fibre intake was associated with improved glycaemic outcomes and insulin resistance; however, these associations were attenuated by anthropometric and lifestyle covariates.

The effect of spirulina sauce on glycemic index, lipid profile, and oxidative stress in type 2 diabetic patients: A randomized double-blind clinical trial

We aimed to evaluate the effect of spirulina sauce on glycemic indices, lipid profile, oxidative stress markers, and anthropometric measurement in type 2 diabetic patients. Forty patients were randomly assigned to receive 20 g/day spirulina sauce (containing 2 g of spirulina) or placebo for 2 months. Anthropometric and biochemical indices were measured at the beginning and end of the intervention. Fasting blood glucose (mean difference (MD): -15.3 mg/dL, 95% confidence (CI): -44.2 to 13.60, p = .26), HbA1c (MD: 0.13%, 95% CI: -0.83 to 0.57, p = .75), insulin (MD: -1.46 μIU/mL, 95% CI: -4.0 to 1.09, p = .28), and HOMA-IR (MD: -0.35, 95% CI: -2.0 to 1.32, p = .68) did not change significantly between groups. QUICKI increased significantly (MD: 0.025, 95% CI: 0.006 to 0.045, p = .03). Among the lipid profile, triglyceride (TG) (MD: -68.6 mg/dL, 95% CI: -107.21 to -29.98, p < .001), total cholesterol (MD: -29.55 mg/dL, 95% CI: -55.28 to -3.81, p = .02), and LDL (MD: -17.7 mg/dL, 95% CI: -33.24 to -2.15, p = .01) were significantly decreased in the spirulina group compared to the control; whereas, the change in HDL was non-significant. No significant change was observed in body composition and anthropometric measurements, except waist circumference, which was reduced (MD: -2.65 cm, 95% CI: -3.91 to -1.38, p = .001). Hunger index significantly decreased and fullness increased marginally significantly. Although malondialdehyde was significantly reduced, no change was observed in total antioxidant capacity (TAC). Spirulina sauce was not effective for glycemic control in type 2 diabetes; however, could be useful for controlling appetite and ameliorating lipid profile.

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.

Dietary Fibre Intake in Chile: 13 Years after the Last National Report

BACKGROUND

The objective is to provide updated data on the intake of total dietary fibre in the population residing in Chile and to identify food sources that contribute most to its intake, as well as its association with different sociodemographic and nutritional status-related determinants.

METHODS

In this descriptive cross-sectional study, a nationwide survey was applied to determine fibre intake using an instrument that has been previously validated in the resident population of Chile.

RESULTS

The sample consisted of a total of 1761 participants. Dietary fibre intake was 12.8 ± 7.1 g/day for the total population, and 90% of participants did not meet the recommendation, with no differences in consumption by sex, geographical area, and the urban/rural population. A lower consumption was found among participants with overweight and obesity. According to food groups, bread was the major contributor to fibre intake, providing 4.39 ± 3.05 g/day, followed by cereals (2.26 ± 2.80 g/day) and vegetables (1.85 ± 1.59 g/day).

CONCLUSIONS

90% of the population consume less fibre than recommended, and bread is the main food source; these data are critical for the development of strategies that are aimed at changing habits in order to improve diet quality.

The effects of acarbose treatment on cardiovascular risk factors in impaired glucose tolerance and diabetic patients: a systematic review and dose-response meta-analysis of randomized clinical trials

Acarbose (ACB) seems to be an effective drug in the management of cardiovascular risk factors. However, no previous meta-analysis of randomized controlled trials (RCTs) has been done to evaluate the effects of ACB on cardiovascular risk factors on impaired glucose tolerance (IGT), type 2 diabetes mellitus (T2D), and type 1 diabetes mellitus (T1D). We comprehensively searched electronic databases including Scopus, Web of Science, and PubMed for RCTs for related keywords up to September 2022. A random-effects model was used to estimate the weighted mean difference (WMD) and 95% confidence interval (CI). The pooled analysis demonstrated that ACB treatment had a significant effect on fasting blood glucose (FBG) (WMD = -3.55 mg/dL; 95%CI: -6.29, -0.81; p = 0.011), fasting insulin (WMD = -6.73 pmoL/L; 95%CI: -10.37, -3.10; p < 0.001), HbA1c [WMD = -0.32%; 95%CI: -0.45, -0.20; p < 0.001], body weight (WMD = -1.25 kg; 95%CI: -1.79, -0.75; p < 0.001), body mass index (BMI) (WMD = -0.64 kg/m2; 95%CI: -0.92, -0.37; p < 0.001), tumor necrosis factor-alpha (TNF-α) (WMD = -2.70 pg/mL, 95%CI: -5.25, -0.16; p = 0.037), leptin (WMD = -1.58 ng/mL; 95%CI: -2.82, -0.35; p = 0.012), alanine transaminase (ALT) (WMD = 0.71 U/L; 95%CI: -0.31, 1.85; p = 0.164), triglyceride (TG) (WMD = -13.89 mg/dL; 95%CI: -20.69, -7.09; p < 0.001), total cholesterol (TC) (WMD = -2.26 mg/dL; 95%CI: -4.18, -0.34; p = 0.021), systolic blood pressure (SBP) (WMD = -1.29 mmHg; 95%CI: -2.44, -0.15; p = 0.027), and diastolic blood pressure (DBP) (WMD = 0.02 mmHg; 95%CI: -0.41, 0.45; p = 0.925) in an intervention group, compared with a placebo group. The non-linear dose-response analysis showed that ACB reduces the TC in trial duration by >50 weeks, and 180 mg/day is more effective for the decrement of CRP. ACB can improve lipid profiles, glycemic indices, anthropometric indices, and inflammatory markers in T2D, T1D, and IGT patients.

The effects of hesperidin supplementation on cardiovascular risk factors in adults: a systematic review and dose-response meta-analysis

Hesperidin is a naturally occurring bioactive compound that may have an impact on cardiovascular disease risks, but the evidence is not conclusive. To investigate further, this study aimed to explore the effects of hesperidin supplementation on cardiovascular risk factors in adults. A comprehensive search was conducted up to August 2022 using relevant keywords in databases such as Scopus, PubMed, Embase, Cochrane Library, and ISI Web of Science for all randomized controlled trials (RCTs). The results showed that hesperidin supplementation had a significant effect on reducing serum triglyceride (TG), total cholesterol (TC), low-density cholesterol (LDL), tumor necrosis factor-alpha (TNF-α), and systolic blood pressure (SBP), whereas weight was increased. However, no significant effect was observed on high-density cholesterol (HDL), waist circumference (WC), fasting blood glucose (FBG), insulin, homeostatic model assessment for insulin resistance (HOMA-IR), C-reactive protein (CRP), interleukin-6 (IL-6), body mass index (BMI), and diastolic blood pressure (DBP). The study also found that an effective dosage of hesperidin supplementation was around 1,000 mg/d, and a more effective duration of supplementation was more than eight weeks to decrease insulin levels. Furthermore, the duration of intervention of more than six weeks was effective in decreasing FBG levels.

Carbohydrates for glycemic control: functional and microbiome aspects

PURPOSE OF REVIEW

Glycemia goals are used as indicators of control and progression in prediabetes and diabetes. Adopting healthy eating habits is essential. It is worth considering the quality of carbohydrates to help with dietary glycemic control. The present article aims to review recent meta-analyses published in the years 2021-2022 on the effects of dietary fiber and low glycemic index/load (LGI/LGL) foods on glycemic control and how gut microbiome modulation contributes to glycemic control.

RECENT FINDINGS

Data involving more than 320 studies were reviewed. The evidence allows us to infer that LGI/LGL foods, including dietary fiber intake, are associated with reduced fasting glycemia and insulinemia, postprandial glycemic response, HOMA-IR, and glycated hemoglobin, which are more evident in soluble dietary fiber. These results can be correlated with changes in the gut microbiome. However, the mechanistic roles of microbes or metabolites implicated in these observations continue to be explored. Some controversial data highlight the need for more homogeneity between studies.

SUMMARY

The properties of dietary fiber are reasonably well established for their glycemic homeostasis effects, including the fermentation aspects. Findings of gut microbiome correlations with glucose homeostasis can be incorporated into clinical nutrition practice. Target dietary fiber interventions on microbiome modulation can offer options to improve glucose control and contribute to personalized nutritional practices.

Physicochemical, structure properties and in vitro hypoglycemic activity of soluble dietary fiber from adlay (Coix lachryma-jobi L. var. ma-yuen Stapf) bran treated by steam explosion

To enhance the content of adlay bran soluble dietary fiber (SDF) and improve its functionality, we investigated the influences of steam explosion (SE) on the physicochemical, structural properties, and in vitro hypoglycemic activities of adlay bran SDF. The cellulose, hemicellulose, and lignin contents of adlay bran decreased significantly after SE treatment. When the SE strength was 0.8 MPa for 3 min, the SDF content was 9.37%, which was a significant increase of 27.48% compared to the control. Under these conditions, SDF showed the highest oil-holding capacity (OHC) (2.18 g/g), cholesterol adsorption capacity (CAC) (27.29 mg/g), glucose adsorption capacity (GAC) (15.54 mg/g), glucose dialysis retardation index (GDRI) (36.57%), and α-Amylase activity inhibition ratio (α-AAIR) (74.14%). Compared with SDF from untreated adlay bran, SDF from SE-treated adlay bran showed lower weight molecular. In addition, differential scanning calorimetry (DSC) measurement showed that the peak temperature of SDF from adlay bran treated by SE increased by 4.19°C compared to the untreated SDF sample. The structure of SDF from adlay bran treated by SE showed that the SDF surface was rough and poriferous and the specific surface areas increased. In conclusion, SE pretreatment increases the content of SDF in adlay bran and improves its physicochemical, structural properties, and biological activities, which will be beneficial for the further exploitation of adlay bran.

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.

The effects of L-carnitine supplementation on glycemic markers in adults: A systematic review and dose-response meta-analysis

Background and aims

Hyperglycemia and insulin resistance are concerns today worldwide. Recently, L-carnitine supplementation has been suggested as an effective adjunctive therapy in glycemic control. Therefore, it seems important to investigate its effect on glycemic markers.

Methods

PubMed, Scopus, Web of Science, and the Cochrane databases were searched in October 2022 for prospective studies on the effects of L-carnitine supplementation on glycemic markers. Inclusion criteria included adult participants and taking oral L-carnitine supplements for at least seven days. The pooled weighted mean difference (WMD) was calculated using a random-effects model.

Results

We included the 41 randomized controlled trials (RCTs) (n = 2900) with 44 effect sizes in this study. In the pooled analysis; L-carnitine supplementation had a significant effect on fasting blood glucose (FBG) (mg/dl) [WMD = -3.22 mg/dl; 95% CI, -5.21 to -1.23; p = 0.002; I ² = 88.6%, p < 0.001], hemoglobin A1c (HbA1c) (%) [WMD = -0.27%; 95% CI, -0.47 to -0.07; p = 0.007; I ² = 90.1%, p < 0.001] and homeostasis model assessment-estimate insulin resistance (HOMA-IR) [WMD = -0.73; 95% CI, -1.21 to -0.25; p = 0.003; I ² = 98.2%, p < 0.001] in the intervention compared to the control group. L-carnitine supplementation had a reducing effect on baseline FBG ≥100 mg/dl, trial duration ≥12 weeks, intervention dose ≥2 g/day, participants with overweight and obesity (baseline BMI 25-29.9 and >30 kg/m²), and diabetic patients. Also, L-carnitine significantly affected insulin (pmol/l), HOMA-IR (%), and HbA1c (%) in trial duration ≥12 weeks, intervention dose ≥2 g/day, and participants with obesity (baseline BMI >30 kg/m²). It also had a reducing effect on HOMA-IR in diabetic patients, non-diabetic patients, and just diabetic patients for insulin, and HbA1c. There was a significant nonlinear relationship between the duration of intervention and changes in FBG, HbA1c, and HOMA-IR. In addition, there was a significant nonlinear relationship between dose (≥2 g/day) and changes in insulin, as well as a significant linear relationship between the duration (weeks) (coefficients = -16.45, p = 0.004) of intervention and changes in HbA1C.

Conclusions

L-carnitine could reduce the levels of FBG, HbA1c, and HOMA-IR.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier: CRD42022358692.

[Nutrition for diabetic patients (Update 2023)]

All patients with diabetes require individual and personalized nutritional consultation with professionals. The patient's needs should be the primary focus of the dietary therapy, taking their lifestyle and the type of diabetes into consideration. With the recommendations to the patient's diet, there need to be specific metabolic goals to reduce the disease's progression and to avoid long term health effects. Therefore, practical guidelines such as portion size and meal planning tips should be the main focus.According to the latest national and international standards, patients suffering from diabetes should have access to nutrition consulting and nutritional training. During consultation they can be supported on- how to manage their health condition and choosing food and beverage to improve their health.These practical recommendations sum up the latest literature on nutritional aspects of diabetes treatment.

Enhancing intestinal barrier efficiency: A novel metabolic diseases therapy

Physiologically, the intestinal barrier plays a crucial role in homeostasis and nutrient absorption and prevents pathogenic entry, harmful metabolites, and endotoxin absorption. Recent advances have highlighted the association between severely damaged intestinal barriers and diabetes, obesity, fatty liver, and cardiovascular diseases. Evidence indicates that an abated intestinal barrier leads to endotoxemia associated with systemic inflammation, insulin resistance, diabetes, and lipid accumulation, accelerating obesity and fatty liver diseases. Nonetheless, the specific mechanism of intestinal barrier damage and the effective improvement of the intestinal barrier remain to be explored. Here, we discuss the crosstalk between changes in the intestinal barrier and metabolic disease. This paper also highlights how to improve the gut barrier from the perspective of natural medicine, gut microbiota remodeling, lifestyle interventions, and bariatric surgery. Finally, potential challenges and prospects for the regulation of the gut barrier-metabolic disease axis are discussed, which may provide theoretical guidance for the treatment of metabolic diseases.

The α-Amylase and α-Glucosidase Inhibition Capacity of Grape Pomace: A Review

The concept of functional foods is gaining more importance due to its role in maintaining a healthy status and preventing some metabolic diseases. The control of diabetes, in particular type-2 (T2DM), could be considered a big challenge since it involves other factors such as eating habits. From the pharmacological point of view, inhibiting digestive enzymes, such as α-amylase and α-glucosidase, is one of the mechanisms mainly used by synthetic drugs to control this disease; however, several side effects are described. For that reason, using bioactive compounds may appear as an alternative without presenting the complications synthetic drugs available on the market have. The winemaking industry generates tons of waste annually, and grape pomace (GP) is the most important. GP is recognized for its nutritional value and as a source of bioactive compounds that are helpful for human health. This review highlights the importance of GP as a possible source of α-amylase and α-glucosidase inhibitors. Also, it is emphasized the components involved in this bioactivity and the possible interactions among them. Especially, some phenolic compounds and fiber of GP are the main ones responsible for interfering with the human digestive enzymes. Preliminary studies in vitro confirmed this bioactivity; however, further information is required to allow the specific use of GP as a functional ingredient inside the market of products recommended for people with diabetes.

Graphical abstract

The effects of conjugated linoleic acid supplementation on inflammatory cytokines and adipokines in adults: A GRADE-assessed systematic review and dose-response meta-analysis

Background and aims

Many studies have investigated the effect of conjugated linoleic acid (CLA) supplementation on inflammatory cytokines and adipokines. However, the results of these studies are not consistent. Therefore, this systematic review and meta-analysis were designed to comprehensively evaluate the effect of CLA supplementation on inflammatory cytokines and adipokines.

Methods

Randomized controlled trials (RCTs) examining the effects of CLA supplementation on C-reactive protein (CRP), interleukin 6 (IL-6), tumor necrosis factor-alpha (TNF-α), adiponectin, and leptin, published up to March 2022, were identified through PubMed, SCOPUS, and ISI Web of Science databases. A random-effects model was used to calculate weighted mean differences (WMDs) with 95% confidence intervals (CI) for 42 studies that included 1,109 participants.

Results

Findings from 42 studies with 58 arms indicated that CLA supplementation significantly decreased IL-6 and TNF-α levels and also slightly increased CRP levels. However, adiponectin and leptin levels did not change after CLA supplementation. A subgroup analysis found that CLA supplementation reduced adiponectin and leptin in women.

Conclusion

Our results demonstrated that CLA supplementation increased CRP levels and decreased TNF-α and IL-6 levels. Therefore, it seems that CLA can have both proinflammatory and anti-inflammatory roles.

Systematic review registration

https://www.crd.york.ac.uk/prospero/, identifier (CRD42022331110).

The effects of berberine supplementation on cardiovascular risk factors in adults: A systematic review and dose-response meta-analysis

Cardiovascular disease (CVD) is a major concern today. Herbal medicine is one helping way to control CVD risks. One conclusive of herbal medicine is Berberine (BBR) and converse about it still exists, to clarify this issue, this meta-analysis was performed. PubMed/Medline, Scopus, and Web of Science were searched for RCTs in adults on the effect of BBR supplementation on CVD risk factors up to July 2022. The pooled results showed BBR significantly reduced triglyceride (WMD = -23.70 mg/dl; 95%CI -30.16, -17.25; P < 0.001), total cholesterol (WMD = -20.64 mg/dl; 95%CI -23.65, -17.63; P < 0.001), low-density lipoprotein WMD = -9.63 mg/dl; 95%CI, -13.87, -5.39; P < 0.001), fasting blood glucose (FBG) (WMD = -7.74 mg/dl; 95%CI -10.79, -4.70; P < 0.001), insulin (WMD = -3.27 mg/dl; 95%CI -4.46,-2.07; P < 0.001), HbA1c (WMD = -0.45%; 95%CI -0.68, -0.23; P < 0.001), HOMA-IR (WMD = -1.04; 95%CI -1.55, -0.52; P < 0.001), systolic blood pressure (WMD = -5.46 mmHg; 95%CI -8.17, -2.76; P < 0.001), weight (WMD = -0.84; 95%CI -1.34,-0.34; P < 0.001), body mass index (WMD = -0.25 kg/m2; 95%CI -0.46, -0.04; P = 0.020), while increased high-density lipoprotein (HDL) (WMD = 1.37 mg/dl; 95%CI 0.41,2.23; P = 0.005). The optimal dose of BBR was 1 g/day for TG, TC, and weight, 1.8 g/day for insulin and HOMA-IR, and 5 g/day for HDL. FBG's most efficient time frame was 40 weeks from the beginning of supplementation, whereas DBP and waist circumference was 50 weeks. In conclusion, the lipid profile, FBG balance, obesity parameters, and SBP were improved with BBR supplementation.

Systematic review registration

CRD42022347004.

Associations between dietary fiber intake and cardiovascular risk factors: An umbrella review of meta-analyses of randomized controlled trials

Although several meta-analyses have revealed the beneficial effects of dietary fiber intake on human health, some have reported inconsistent findings. The purpose of this work was to perform an umbrella meta-analysis to evaluate the relevant evidence and elucidate the effect of dietary fiber intake on glycemic control, lipid profiles, systematic inflammation, and blood pressure. Eligible studies were searched in several electronic databases, including Web of Science, PubMed, Scopus, and the Cochrane Library, up to March 2022. A total of 52 meta-analyses involving 47,197 subjects were identified to assess the pooled effect size. Overall, higher dietary fiber intake was significantly associated with reductions in parameters involving glycemic control, including fasting plasma glucose (ES = -0.55, 95% CI: -0.73, -0.38, P < 0.001), fasting plasma insulin (ES = -1.22, 95% CI: -1.63, -0.82, P < 0.001), homeostasis model assessment of insulin resistance (HOMA-IR) (ES = -0.43, 95% CI: -0.60, -0.27, P < 0.001), and glycosylated hemoglobin (HbA1c) (ES = -0.38, 95% CI: -0.50, -0.26, P < 0.001). In terms of lipid profiles, higher dietary fiber intake was associated with significant reductions in the serum level of total cholesterol (ES = -0.28, 95% CI: -0.39, -0.16, P < 0.001) and low-density lipoprotein cholesterol (ES = -0.25, 95% CI: -0.34, -0.16, P < 0.001), but not triglycerides (ES = -0.001, 95% CI: -0.006, 0.004, P = 0.759) and high-density lipoprotein cholesterol (ES = -0.002, 95% CI: -0.004, 0.000, P = 0.087). Higher dietary fiber intake was also significantly associated with improved tumor necrosis factor-alpha serum levels (ES = -0.78, 95% CI: -1.39, -0.16, P = 0.013), while no significant effect was observed for C-reactive protein (ES = -0.14, 95% CI: -0.33, 0.05, P = 0.156). Finally, blood pressure was also significantly improved following higher dietary fiber intake (systolic blood pressure: ES = -1.72, 95% CI: -2.13, -1.30, P < 0.001; diastolic blood pressure: ES = -0.67, 95% CI: -0.96, -0.37, P < 0.001). Subgroup analysis revealed that the study population and type of dietary fiber could be partial sources of heterogeneity. In conclusion, the present umbrella meta-analysis provides evidence for the role of dietary fiber supplementation in the improvement of established cardiovascular risk factors.

Nutritional strategies to attenuate postprandial glycemic response

Maintaining good glycemic control to prevent complications is crucial in people with type 2 diabetes and in people with prediabetes and in the general population. Different strategies to improve glycemic control involve the prescription of blood glucose-lowering drugs and the modulation of physical activity and diet. Interestingly, lifestyle intervention may be more effective in lowering hyperglycemia than pharmaceutical intervention. Regulation of postprandial glycemia is complex, but specific nutritional strategies can be applied to attenuate postprandial hyperglycemia. These strategies include reducing total carbohydrate intake, consuming carbohydrates with a lower glycemic index, the addition of or substitution by sweeteners and fibers, using food compounds which delay or inhibit gastric emptying or carbohydrate digestion, and using food compounds which inhibit intestinal glucose absorption. Nevertheless, it must be noted that every individual may respond differently to certain nutritional interventions. Therefore, a personalized approach is of importance to choose the optimal nutritional strategy to improve postprandial glycemia for each individual, but this requires a better understanding of the mechanisms explaining the differential responses between individuals.

The effect of dietary fiber supplement on prevention of gestational diabetes mellitus in women with pre-pregnancy overweight/obesity: A randomized controlled trial

Objective: To investigate the effect of dietary fiber intake during pregnancy on the prevention of gestational diabetes mellitus (GDM) in women who are overweight/obese prior to pregnancy.

Methods: This randomized controlled trial was conducted in Shanghai General Hospital from June 2021 to March 2022. A total of 98 women who reported BMI≥24 kg/m² prior to pregnancy were recruited before their 20th gestational week, and randomly (simple random allocation) assigned to the fiber supplement group (12 g of dietary fiber power twice daily) and the control group (standard prenatal care) from 20 to 24⁺⁶ gestational weeks. Both groups received nutrition education and dietary advice during the study. GDM diagnosis was performed by an oral glucose tolerance test (OGTT) at 25–28 weeks’ gestation. Data are presented as means with SD, as medians with IQR, or as counts with percentages as appropriate. Comparisons were conducted using a t-test, Mann-Whitney U test, and χ² test, respectively.

Results: The incidence of GDM was significantly reduced in the fiber supplement group compared with the control group: 8.3 vs. 24.0% (χ² = 4.40, p = 0.036). At OGTT, the mean fasting plasma glucose in the fiber supplement group was significantly lower than before the intervention (4.57 ± 0.38 mmol/L vs. 4.41 ± 0.29 mmol/L, p < 0.01) but not in the control group (4.48 ± 0.42 mmol/L vs. 4.37 ± 0.58 mmol/L, p = 0.150). Compared with the control group, the TG and TG/HDL-C ratio levels in the intervention group were significantly higher than those in the control group (2.19 ± 0.54 mmol/L vs. 2.70 ± 0.82 mmol/L and 1.19 ± 0.49 vs.1.63 ± 0.63, respectively, all P＜0.05). The body weight gain was significantly lower in the fiber supplement group than the control group (1.99 ± 1.09 kg vs. 2.53 ± 1.20kg, p = 0.022). None of the women randomized to the fiber supplement group experienced preterm birth (<37 weeks gestation) compared with 12.0% in the control group (p = 0.040). Excessive weight gain (total weight gain >11.5 kg for overweight, and >9.0 kg for obesity) occurred in 46.7% of women in the fiber supplement group compared with 68.0% in the control group (p = 0.035). There were no differences in other maternal and neonatal outcomes.

Conclusion: Increased dietary fiber intake in pregnant women who were overweight/obese prior to pregnancy may reduce the risk of GDM, excessive weight gain, and preterm birth, but it did not improve blood lipids.

Associations between dietary fiber intake and mortality from all causes, cardiovascular disease and cancer: a prospective study

OBJECTIVE

Several studies suggest that dietary fiber intake may reduce mortality risk, but this might depend on the fiber types and the evidence regarding the role of soluble fiber or insoluble fiber on death risk remain limited and inconsistent. Therefore, this study aimed to comprehensively evaluate multiple types of dietary fiber intake on mortality from all causes, cardiovascular disease and cancer in the large-scale Prostate, Lung, Colorectal, and Ovarian Cancer (PLCO) Screening Trial.

METHODS

A multivariate Cox proportional hazards model was used to estimate hazard ratios (HRs) and 95% confidence intervals (CIs).

RESULTS

This study finally included 86,642 participants with 17,536 all-cause deaths, 4842 cardiovascular deaths and 5760 cancer deaths identified after a total of 1,444,068 follow-up years. After adjusting for potential confounders, dietary total fiber intake was statistically significantly inversely associated with all-cause death (Q5 vs Q1: HR 0.71, 95% CI 0.66-0.75; P for trend < 0.001), cardiovascular death (Q5 vs Q1: HR 0.73, 95% CI 0.65-0.83; P for trend < 0.001) and cancer mortality (Q5 vs Q1: HR 0.77, 95% CI 0.69-0.86; P for trend < 0.001). Similar results were observed for both insoluble and soluble fiber intake. Restricted cubic spline model analysis suggested that there was a nonlinear association of dietary fiber intake with mortality risk (all P for nonlinearity < 0.05).

CONCLUSIONS

In this large nationally representative sample of US adult population, intakes of total fiber, soluble fiber, and insoluble fiber were associated with lower risks of all-cause, cardiovascular and cancer mortality.

Healthful Plant-Based Diet and Incidence of Type 2 Diabetes in Asian Population

Plant-based diets have been suggested to be beneficial for type 2 diabetes (T2D). However, studies investigating the association between the healthiness of a plant-based diet and T2D risk are limited. This study explored the prospective association between scores from three different plant-based diet indices and risk of T2D and investigated whether associations differ by demographic and lifestyle factors in the Korean population. Data were derived from the Korean Genome and Epidemiology Study (KoGES), a prospective cohort study initiated between 2001 and 2002. Dietary intakes were assessed using a validated food frequency questionnaire. Scores for three plant-based diet indices (overall plant-based diet index (PDI), healthful plant-based diet index (hPDI), and unhealthful plant-based diet index (uPDI)) were measured. A total of 7363 Korean adults aged 40–69 years without T2D and related chronic diseases at baseline were included. Incident T2D was defined as elevated plasma glucose (≥126 mg/dL), self-report of a doctor’s diagnosis of T2D, or use of oral hypoglycemic drug. Multivariable Cox proportional hazards models were used to estimate hazard ratios (HRs) and 95% CIs for T2D risk. During a follow-up period of 14 years, 977 participants developed T2D. A 10-point higher score in hPDI was associated with a 14% lower risk of T2D (HR: 0.86, 95% CI, 0.77–0.95), adjusting for potential confounders. In subgroup analysis, inverse associations between hPDI and T2D risk were stronger in participants with a family history of T2D (HR: 0.58, 95% CI, 0.44 0.76) or history of hypertension (HR: 0.73, 95% CI, 0.60 0.89) than those without a family history of T2D (p interaction = 0.01) or history of hypertension (p interaction = 0.04). Considering the quality of the plant foods may be important for the prevention of T2D in the Korean population, which habitually consumes diets rich in plant foods.

Association of Dietary Fiber Intake with All-Cause Mortality and Cardiovascular Disease Mortality: A 10-Year Prospective Cohort Study

Although previous studies have established that dietary fiber (DF) intake reduces the total cardiovascular disease (CVD) mortality in general populations, limited studies have been conducted in individuals with pre-existing chronic conditions, especially in Asian countries. We aimed to investigate the association of DF intake with all-cause and CVD mortality in the general population and in the subpopulation with hypertension, diabetes, and dyslipidemia. We examined the relationship between DF intake and all-cause and CVD mortality using the Korean genome and epidemiology study. Diet was assessed using a food-frequency questionnaire at baseline. Cox proportional hazard models were used to estimate the hazard ratio (HR) and 95% confidence intervals (CIs) after adjusting for confounders. During the mean 10.1 years of follow-up, higher DF intake was significantly associated with a lower risk of all-cause mortality after adjusting for confounders (HR and 95% CIs for Q5 vs. Q1: 0.84 (0.76−0.93); p < 0.001). DF intake was inversely associated with a lower risk of CVD mortality after adjusting for the same confounders (HR and 95% CIs for Q5 vs. Q1: 0.61 (0.47−0.78); p < 0.001). Total DF intake was inversely associated with all-cause and CVD mortality in middle-aged and older adults.

The Effect of Rye-Based Foods on Postprandial Plasma Insulin Concentration: The Rye Factor

Consumption of whole grain has been associated with lower incidence of type-2 diabetes, cardiovascular disease and their risk factors including improved glycemic control. In comparison with other whole grain products, rye bread has been shown to induce lower insulin response in the postprandial phase, without affecting the glucose response. This phenomenon has been referred to as the “rye factor” and is being explored in this review where we summarize the findings from meal and extended meal studies including rye-based foods. Overall, results from intervention studies showed that rye-based foods vs. (wheat) control foods had positive effect on both insulin and glucose responses in the postprandial phase, rather than on insulin alone. Mechanistic studies have shown that the rye factor phenomenon might be due to slowing of the glucose uptake in the intestine. However, this has also been shown for wheat-based bread and is likely an effect of structural properties of the investigated foods rather than the rye per se. More carefully controlled studies where standardized structural properties of different cereals are linked to the postprandial response are needed to further elucidate the underlying mechanisms and determinants for the effect of specific cereals and product traits on postprandial glycemic control.

The effects of dietary supplements and natural products targeting glucose levels: an overview

Identifying effective dietary supplements and medicinal herbs has attracted the attention of clinicians and researchers to complement the standard treatment in controlling diabetes mellitus. In the present overview, we aimed to collect studies with the highest level of evidence to shed light on detecting the most effective dietary supplements and medicinal herbs for controlling glycemic status. For the current overview, four electronic databases, including PubMed, Scopus, Web of Science, and Cochrane Library, were systematically searched from inception to 31 December 2020 and then updated until 1 October 2021 to obtain eligible meta-analyses on either dietary supplements or medicinal herbs and their effects on glycemic status. Fasting blood sugar (FBS) and Hemoglobin A1C (HbA1C) were considered as primary outcomes. Finally, ninety-one meta-analyses on dietary supplements (n = 55) and herbs (n = 36) were included. Evidence showed positive effects of chromium, zinc, propolis, aloe vera, milk thistle, fenugreek, cinnamon, ginger, and nettle on FBS and/or HbA1C. However, mostly the heterogeneity (I2) was high. Other supplements and herbs also showed no reduction in glucose levels or their effects were small. Although some dietary supplements and medicinal herbs showed a significant reduction in FBS and/or HbA1C, mostly their effects from the clinical point of view were not remarkable. In addition, due to high heterogeneity, publication bias, and a limited number of included studies in most cases further clinical trials are needed for making decision on anti-diabetic supplement efficacy.

Effect of l-Arginine Supplementation on Blood Pressure in Adults: A Systematic Review and Dose-Response Meta-analysis of Randomized Clinical Trials

A decade-old meta-analytic work indicated that l-arginine supplementation might have a blood pressure (BP)-lowering effect in different populations. However, several relevant investigations have emerged in the last 10 y, and an up-to-date systematic review and meta-analysis on this topic is currently lacking. Therefore, we aimed to examine the impact of l-arginine supplementation on BP by conducting a systematic review and dose-response meta-analysis of randomized placebo-controlled clinical trials (RCTs). We searched online databases using relevant keywords up to April 2021 to identify RCTs using oral l-arginine on systolic BP (SBP) and diastolic BP (DBP) in adults. Inclusion criteria were adult participants and an intervention duration ≥4 d. Exclusion criteria were the use of l-arginine infusion and acute interventions. A random-effects model was used to estimate the weighted mean difference (WMD) and 95% CI. Twenty-two RCTs with 30 effect sizes were included in this meta-analysis. The pooled analysis demonstrated significant decreases in SBP (WMD = -6.40 mmHg; 95% CI: -8.74, -4.05; P < 0.001) and DBP (WMD = -2.64 mmHg; 95% CI: -3.94, -1.40; P < 0.001) after l-arginine supplementation. Subgroup analysis showed significant reductions in SBP and DBP regardless of baseline BP category (normotensive, hypertensive), study duration (≤24 d, >24 d), sex (female, male), health status (healthy, unhealthy), and BMI (normal, overweight, obese). No significant changes were observed with dosages >9 g/d, trial duration >24 d, or in obese individuals. l-Arginine supplementation also appears to decrease DBP more effectively in females than in males. Moreover, meta-regression analysis for DBP demonstrated a significant relation between the dose of l-arginine intake and changes in DBP (P = 0.020). In the nonlinear dose-response analysis, the effective dosage of l-arginine supplementation was detected to be ≥4 g/d for SBP (P = 0.034), independent of trial duration. Overall, l-arginine supplementation may be effective for decreasing BP. This study was registered at PROSPERO as CRD42021242772.