A high-legume low-glycemic index diet reduces fasting plasma leptin in middle-aged insulin-resistant and -sensitive men

Pulse Consumption and Health Outcomes: A Scoping Review

Pulses-comprising the dry, edible seeds of leguminous plants-have long been lauded for their culinary flexibility and substantial nutritional advantages. This scoping review aimed to map the evidence on how pulses contribute to overall human health. Four electronic databases were searched for clinical and observational studies in English. We identified 30 articles (3 cross-sectional studies, 1 federated meta-analysis, 8 prospective cohort studies, 1 before-and-after study, and 17 randomized controlled trials) that met our inclusion criteria. Predominant among the pulses studied were lentils, chickpeas, common bean varieties (e.g., pinto, black, navy, red, kidney), black-eyed peas, cowpeas, and split peas. Consumption modalities varied; most studies examined mixed pulses, while five isolated individual types. In intervention studies, pulses were incorporated into diets by allotting a fixed pulse serving on top of a regular diet or by substituting red meat with pulses, offering a comparative analysis of dietary effects. The health outcomes evaluated were multifaceted, ranging from lipid profiles to blood pressure, cardiovascular disease risk and mortality, type 2 diabetes and glycemic control, metabolic syndrome indicators, inflammatory markers, oxidative stress biomarkers, and hormonal profiles. The most frequently assessed study outcomes included changes in low-density lipoprotein cholesterol, high-density lipoprotein cholesterol, systolic blood pressure, diastolic blood pressure, fasting blood sugar, hemoglobin A1c, waist circumference, and C-reactive protein or high-sensitivity C-reactive protein. This review should serve as a call to action for the scientific community to build upon the existing evidence, enriching our understanding of the nutritional and health-promoting attributes of pulses.

Effect of Dietary Fiber on Serum Leptin Level: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Dietary fibers may induce satiety through affecting gastro-intestinal and peripheral appetite regulating hormones. Thus, we aimed to investigate the effect of dietary fiber consumption on serum leptin level compared to control diet, in short- and long- term trials, through a systematic review and meta-analysis.

METHODS

We searched PubMed, web of science, Scopus, ProQuest, EMBASE, and Cochrane Library to find randomized controlled clinical trials that evaluated effect of any type of dietary fiber on serum leptin level compared to control diet, until April 2019. Both short-term (1-4 days) and long-term (longer than 2 weeks) studies were selected. Mean differences (MD) of changes in serum leptin level and 95% confidence intervals were extracted from eligible studies, and random effects model was used to analyze data.

RESULTS

Thirteen studies included the systematic review and 11 entered in the meta-analysis. No significant change was seen in serum leptin level in short-term (MD=0.02, 95% CI; -0.15, 0.20, Tau²=0.0) and long-term studies (MD=-0.10, 95% CI; -0.28, 0.08, Tau²=0.0), followed by fiber consumption. However, this effect was statistically significant in obese participants (MD=-0.36, 95% CI; -0.71, -0.02, Tau²=0.0) in long-term studies. Moreover, we found no significant results in subgroups of baseline serum leptin level, intervention duration, fiber dose, and fiber type.

CONCLUSIONS

This meta-analysis found that taking dietary fiber for long term could lower serum leptin level, just in obese persons. However, further clinical trials are needed in this field to clarify this issue.

Legume consumption increase adiponectin concentrations among type 2 diabetic patients: A randomized crossover clinical trial

BACKGROUND AND OBJECTIVE

This randomized crossover clinical trial investigated the effects of substituting legumes for meat consumption in the therapeutic lifestyle change (TLC) diet on leptin and adiponectin concentrations among type 2 diabetic patients.

MATERIAL AND METHODS

Thirty-one type 2 diabetic patients (24 women, age: 58.1±6.0 years) were randomly assigned to groups designated to consume a legume-free TLC diet or a legume-based TLC diet for 8 weeks. Both diets were similar except for the replacement of two servings of red meat with legumes 3 days per week in the legume-based TLC group. Leptin and adiponectin concentrations were measured at baseline and after the 8-week intervention.

RESULTS

The legume-based TLC diet significantly increased adiponectin concentrations in comparison with the legume-free TLC diet. There was no significant change in leptin concentrations after both intervention diets.

CONCLUSIONS

Legumes increased serum adiponectin concentrations in type 2 diabetic patients. Registration number: IRCT201202251640N7.

Effect of cowpea flour processing on the chemical properties and acceptability of a novel cowpea blended maize porridge

Childhood growth stunting is a pervasive problem in Malawi and is in large part due to low quality complementary foods and chronic gut inflammation. Introducing legumes such as cowpea (Vigna unguiculata) into the complementary diet has the potential to improve childhood growth by improving diet quality through improvements in macro- and micronutrients and also by reducing gut inflammation. However, cowpea is relatively underutilized in complementary feeding in Malawi due to its strong taste, long processing time, and high energy requirements for processing. Effective utilization of cowpea in complementary feeding requires processing which may affect chemical composition as well as sensory quality. The present study evaluated the effect of processing on the retention of zinc, crude fibre, and flavonoid in roasted, boiled, and dehulled cowpea flours, and assessed the acceptability of maize porridge (70%) enriched with one of the three cowpea flours (30%). Roasting, dehulling, and boiling did not have any effect on zinc content. Crude fibre content increased after processing by all methods. Processing had no effect on measurable flavonoids. Roasted, boiled, and dehulled cowpea blended maize porridges were acceptable to children with mean quantities of leftover food of less than 3g from the given 100g. Caregivers also rated the blended flours to be highly acceptable to them as well, with maize porridge blended with dehulled cowpea flour the most acceptable to both children and caregivers. These results demonstrate that cowpea flour, processed by any of these three different methods, could serve as a useful addition to maize porridge for complementary feeding of children in sub-Saharan Africa.

The effect of dietary glycemic index and glycemic load on inflammatory biomarkers: a systematic review and meta-analysis of randomized clinical trials

Background

To our knowledge, there is no study available that summarizes earlier findings on the effect of dietary glycemic index (GI) and glycemic load (GL) on inflammatory biomarkers.

Objective

This systematic review and meta-analysis was conducted to systematically review the available clinical trials that examined the effects of low-GI (LGI) and low-GL (LGL) diets on several inflammatory biomarkers in adults.

Design

We searched for relevant articles published up to June 2017 through PubMed, Medline, SCOPUS, EMBASE, and Google Scholar with the use of relevant keywords. Clinical trials that examined the effect of dietary GI and GL on inflammation in adults were included.

Results

Overall, 28 randomized controlled trials (RCTs) including 2961 participants (59% women, 41% men) were included in this meta-analysis. By combining findings from 14 studies on high-sensitivity C-reactive protein (hs-CRP) concentrations, we found no significant effect of LGI or LGL diets on serum hs-CRP concentrations compared with the control diet [weighted mean difference (WMD) for dietary GI: -0.05 mg/L (95% CI: -0.21, 0.10 mg/L); and WMD for dietary GL: 0.08 mg/L (95% CI: -0.26, 0.42 mg/L), respectively]. After combining effect sizes from 5 studies, we did not find significant changes in serum tumor necrosis factor α (TNF-α) concentrations comparing control diets with LGI (WMD: -0.18 mg/L; 95% CI: -0.43, 0.06 mg/L) or LGL (WMD: -0.20 mg/L; 95% CI: -0.33, 0.07 mg/L) diets. Significant changes were also not seen in leptin and interleukin 6 (IL-6) concentrations after the consumption of LGI or LGL diets.

Conclusions

We did not find any significant effect of dietary GI or GL on serum concentrations of inflammatory cytokines, including hs-CRP, leptin, IL-6, and TNF-α in adults. Additional RCTs-in particular, feeding trials-are required to shed light on this issue.

Common beans and cowpeas as complementary foods to reduce environmental enteric dysfunction and stunting in Malawian children: study protocol for two randomized controlled trials

Background

Interventions to decrease the burden of childhood malnutrition are urgently needed, as millions of children die annually owing to undernutrition and hundreds of millions more are left cognitively and physically stunted. Environmental enteric dysfunction (EED), a pervasive chronic subclinical inflammatory condition among children that develops when complementary foods are introduced, places them at high risk of stunting, malabsorption, and poor oral vaccine efficacy. Improved interventions to reduce the burden of EED and stunting are expected to markedly improve the nutritional status and survival of children throughout resource-limited settings.

Methods/Design

We will conduct, in parallel, two prospective randomized controlled clinical trials to determine whether common beans or cowpeas improve growth, ameliorate EED, and alter the intestinal microbiome during a high-risk period in the lives of rural Malawian children. Study 1 will enroll children at 6 months of age and randomize them to receive common beans, cowpeas, or a standard complementary food for 6 months. Anthropometry will be compared among the three groups; EED will be assessed using a dual-sugar absorption test and by quantifying human intestinal mRNA for inflammatory messages; and the intestinal microbiota will be characterized by deep sequencing of fecal DNA, to enumerate host microbial populations and their metabolic capacity. Study 2 will enroll children 12–23 months old and follow them for 12 months, with similar interventions and assessments as Study 1.

Discussion

By amalgamating the power of rigorous clinical trials and advanced biological analysis, we aim to elucidate the potential of two grain legumes to reduce stunting and EED in a high-risk population. Legumes have potential as an affordable and effective complementary food intervention, given their cultural acceptability, nutritional content, and agricultural feasibility in sub-Saharan Africa.

Trial registration

Clinicaltrials.gov NCT02472262 and NCT02472301.

Lifestyle-induced decrease in fat mass improves adiponectin secretion in obese adults

PURPOSE

Several studies have identified relationships between weight loss and adipokine levels; however, none have looked at the combined effect of aerobic exercise training with the consumption of a low- or a high-glycemic diet. We examined the effects of 12 wk of aerobic exercise combined with either a low-glycemic index diet (∼40 U) plus exercise (LoGIX) or a high-glycemic index diet (∼80 U) diet plus exercise (HiGIX) on plasma leptin and adiponectin (total and high molecular weight [HMW]) in 27 older obese adults (age = 65 ± 0.5 yr, body mass index = 34.5 ± 0.7 kg·m).

METHODS

Insulin sensitivity was calculated from an oral glucose tolerance test. Fasting HMW adiponectin and leptin were quantified from plasma samples obtained before the insulin sensitivity index obtained from the oral glucose tolerance test. Glucose and insulin measures were obtained before and every 30 min during the test. Dual-energy x-ray absorptiometry and computerized tomography were used to determine body composition and to quantify subcutaneous and visceral abdominal adiposity, respectively.

RESULTS

Fasting leptin was significantly decreased in both groups (LoGIX: preintervention = 33.8 ± 4.7, postintervention = 19.2 ± 4.5; HiGIX: preintervention = 27.9 ± 4.2, postintervention = 11.9 ± 2.2 ng·mL; P = 0.004), and HMW adiponectin was significantly increased (LoGIX: preintervention = 1606.9 ± 34.6, postintervention = 3502.3 ± 57; HiGIX: preintervention = 3704.8 ± 38.1, postintervention = 4284.3 ± 52.8 pg·mL; P = 0.003) after the 12-wk intervention. Total body fat was reduced after both interventions. Visceral fat mass was inversely correlated with HMW adiponectin, whereas subcutaneous fat correlated with leptin.

CONCLUSIONS

The data suggest that exercise training, independent of dietary glycemic index, favorably alters HMW adiponectin and leptin secretion and that a reduction in visceral fat mass is a key factor regulating HMW adiponectin in older obese persons.

Serum leptin concentrations in relation to dietary patterns in Chinese men and women

OBJECTIVE

The present study aimed to evaluate the independent associations between serum leptin concentration and dietary patterns in a Chinese population.

DESIGN

A cross-sectional study.

SETTING

Data obtained from the 2006 wave of the China Health and Nutrition Survey in Jiangsu Province, China.

SUBJECTS

The sample contained 1061 Chinese adults (488 men and 573 women). BMI was calculated as a parameter of obesity. Factor analysis was used to derive dietary patterns. ANCOVA was performed to assess the associations between serum leptin concentration and the dietary patterns.

RESULTS

Four dietary patterns were derived: Western, High-wheat, Traditional and Hedonic. The Western pattern (rich in meat, milk and cake) was significantly associated with a higher level of serum leptin in men and women, both in an unadjusted model (both P for trend < 0·001) and after adjusting for sex, age, income, total energy intake, physical activity, smoking status and BMI (P for trend = 0·007 for men and P for trend < 0·001 for women). The other three dietary patterns were not significantly associated with serum leptin after adjustment. Sensitivity analysis showed there was an interaction between age and the Western pattern in relation to leptin level. An interaction also existed between current smoking status and the Western pattern.

CONCLUSIONS

Serum leptin concentration was positively associated with the Western dietary pattern in a Chinese population independent of BMI, energy intake and other factors.

Functional foods-based diet as a novel dietary approach for management of type 2 diabetes and its complications: A review

Type 2 diabetes is a complicated metabolic disorder with both short- and long-term undesirable complications. In recent years, there has been growing evidence that functional foods and their bioactive compounds, due to their biological properties, may be used as complementary treatment for type 2 diabetes mellitus. In this review, we have highlighted various functional foods as missing part of medical nutrition therapy in diabetic patients. Several in vitro, animal models and some human studies, have demonstrated that functional foods and nutraceuticals may improve postprandial hyperglycemia and adipose tissue metabolism modulate carbohydrate and lipid metabolism. Functional foods may also improve dyslipidemia and insulin resistance, and attenuate oxidative stress and inflammatory processes and subsequently could prevent the development of long-term diabetes complications including cardiovascular disease, neuropathy, nephropathy and retinopathy. In conclusion available data indicate that a functional foods-based diet may be a novel and comprehensive dietary approach for management of type 2 diabetes.

The association of genetic markers for type 2 diabetes with prediabetic status - cross-sectional data of a diabetes prevention trial

OBJECTIVE

To investigate the association of risk alleles for type 2 diabetes with prediabetes accounting for age, anthropometry, inflammatory markers and lifestyle habits.

DESIGN

Cross-sectional study of 129 men and 157 women of medium-sized companies in northern Germany in the Delay of Impaired Glucose Tolerance by a Healthy Lifestyle Trial (DELIGHT).

METHODS

Besides established risk factors, 41 single nucleotide polymorphisms (SNPs) that have previously been found to be associated with type 2 diabetes were analyzed. As a nonparametric test a random forest approach was used that allows processing of a large number of predictors. Variables with the highest impact were entered into a multivariate logistic regression model to estimate their association with prediabetes.

RESULTS

Individuals with prediabetes were characterized by a slightly, but significantly higher number of type 2 diabetes risk alleles (42.5±4.1 vs. 41.3±4.1, p = 0.013). After adjustment for age and waist circumference 6 SNPs with the highest impact in the random forest analysis were associated with risk for prediabetes in a logistic regression model. At least 5 of these SNPs were positively related to prediabetic status (odds ratio for prediabetes 1.57 per allele (Cl 1.21-2.10, p = 0.001)).

CONCLUSIONS

This explorative analysis of data of DELIGHT demonstrates that at least 6 out of 41 genetic variants characteristic of individuals with type 2 diabetes may also be associated with prediabetes. Accumulation of these risk alleles may markedly increase the risk for prediabetes. However, prospective studies are required to corroborate these findings and to demonstrate the predictive value of these genetic variants for the risk to develop prediabetes.

A high-fibre bean-rich diet versus a low-carbohydrate diet for obesity

BACKGROUND

High-fibre and low-carbohydrate diets may enhance satiety and promote weight loss. We compared a diet rich in beans aiming to increase dietary fibre and promote weight loss with a low-carbohydrate diet in a randomised controlled trial to assess effect and tolerability of the high-fibre bean-rich diet.

METHODS AND RESULTS

One hundred and seventy-three women and men, with a mean body mass index of approximately 36 kg m(-2) (one-fifth with diabetes type 2) were randomised to a high-fibre bean-rich diet that achieved mean (SD) fibre intakes of 35.5 (18.6) g day(-1) for women and 42.5 (30.3) g day(-1) for men, or a low-carbohydrate diet. Both diets were induced gradually over 4 weeks and included a 3-day feeding phase. Among 123 (71.1%) completers at 16 weeks, mean (SD) weight loss was 4.1 (4.0) kg in the high-fibre versus 5.2 (4.5) kg in the low-carbohydrate group [difference, 1.1 kg, 95% confidence interval (CI) = -2.6 to -0.5; P = 0.2], with results similar to the intent-to-treat population. Low-density lipoprotein (LDL)-cholesterol levels decreased with the high-fibre diet (difference in LDL-cholesterol versus low-carbohydrate diet, 0.2 mmol L(-1) , 95% CI = 0.01-0.44 mmol L(-1) ; P = 0.045), as did total cholesterol (P = 0.038), whereas changes in other lipids and glucose did not differ. After 52 weeks, the low-carbohydrate (n = 24) group tended to retain weight loss better than the high-fibre group (P = 0.06), although total cholesterol remained lower with the bean-rich diet (P = 0.049).

CONCLUSIONS

A high-fibre bean-rich diet was as effective as a low-carbohydrate diet for weight loss, although only the bean-rich diet lowered atherogenic lipids.

Adipokines and the cardiovascular system: mechanisms mediating health and disease

This review focuses on the role of adipokines in the maintenance of a healthy cardiovascular system, and the mechanisms by which these factors mediate the development of cardiovascular disease in obesity. Adipocytes are the major cell type comprising the adipose tissue. These cells secrete numerous factors, termed adipokines, into the blood, including adiponectin, leptin, resistin, chemerin, omentin, vaspin, and visfatin. Adipose tissue is a highly vascularised endocrine organ, and different adipose depots have distinct adipokine secretion profiles, which are altered with obesity. The ability of many adipokines to stimulate angiogenesis is crucial for adipose tissue expansion; however, excessive blood vessel growth is deleterious. As well, some adipokines induce inflammation, which promotes cardiovascular disease progression. We discuss how these 7 aforementioned adipokines act upon the various cardiovascular cell types (endothelial progenitor cells, endothelial cells, vascular smooth muscle cells, pericytes, cardiomyocytes, and cardiac fibroblasts), the direct effects of these actions, and their overall impact on the cardiovascular system. These were chosen, as these adipokines are secreted predominantly from adipocytes and have known effects on cardiovascular cells.