Role of resistant starch in improving gut health, adiposity, and insulin resistance

Intake of Potatoes Is Associated with Higher Diet Quality, and Improved Nutrient Intake and Adequacy among US Adolescents: NHANES 2001-2018 Analysis

Potatoes are nutrient rich white vegetables, however, research on their impact on public health is limited. The objective of this study was to provide updated evaluation of the cross-sectional association between potato consumption and diet quality, nutrient intake and adequacy. Twenty-four hour diet recall data from adolescents (n = 16,633; age 9-18 years) were used to assess intakes. Usual intakes of nutrients were determined using the National Cancer Institute method and diet quality was calculated using the Healthy Eating Index-2015 (HEI-2015) after adjusting for demographic factors. Consumers of potatoes (baked or boiled potatoes, mashed potatoes and potato mixtures, fried potatoes, and potato chips) had higher (p < 0.05) HEI-2015 total score and subcomponent scores for total vegetables, total protein foods, and refined grain than non-consumers. Consumers also had higher (p < 0.05) intake of energy, dietary fiber, protein, copper, magnesium, phosphorus, potassium, selenium, sodium, zinc, niacin, vitamin B6, vitamin C, vitamin K and total choline; and higher (p < 0.05) adequacy for protein, copper, magnesium, phosphorus, potassium, zinc, thiamine, niacin, vitamin B6, vitamin C, and vitamin K than non-consumers. In conclusion, adolescent potato consumption was associated with higher diet quality, nutrient intake, and adequacy and therefore encouraging their consumption may be an effective strategy for improving nutritional status.

Gut Health Function of Instant Dehydrated Rice Sticks Substituted with Resistant Starch Types 2 and 4

The purpose of this study was to analyze the effects of instant dehydrated rice sticks (IDRS) which were substituted with resistant starch (RS) types 2 and 4 whose gut health function targets gut microbiota. IDRS are a type of rice noodles that were developed by two formulations. The first formulation had substitution of rice flour with 20% RS type 2 and 0.15% carboxymethyl cellulose (CMC) (RSc-2), and the second formulation had 25% RS type 4 and 0.15% CMC (RSc-4). RSc-2 and RSc-4 were investigated for gut health function by human fecal fermentation in a pH-controlled batch culture. The results of gut microbiota enumeration by fluorescent in situ hybridization confirmed that significantly (P < 0.05) higher numbers of bifidobacteria were obtained with RSc-2 (10.06 ± 0.09 log cells/mL) and RSc-4 (10.00 ± 0.06 log cells/mL) compared to the control (100% rice flour formula) at 24 h fermentation. Additionally, the prebiotic indexes of RSc-2 and RSc-4 were 3.8 and 2.8 -fold higher than that of the control at 24 h fermentation. The short-chained fatty acids, acetic, propionic and butyric acid were analyzed by gas chromatography-flame ionization detector. The butyric acids were significantly (P < 0.05) higher with RSc-2 (43.56 ± 0.01 mM) and RSc-4 (43.63 ± 0.07 mM) compared to the control at 24 h. Thus, RSc-2 and RSc-4 showed butyrogenic, bifidogenic and prebiotic potential to support gut health and could aid in prevention of colon cancer.

Impact of dietary carbohydrate type and protein-carbohydrate interaction on metabolic health

Reduced protein intake, through dilution with carbohydrate, extends lifespan and improves mid-life metabolic health in animal models. However, with transition to industrialised food systems, reduced dietary protein is associated with poor health outcomes in humans. Here we systematically interrogate the impact of carbohydrate quality in diets with varying carbohydrate and protein content. Studying 700 male mice on 33 isocaloric diets, we find that the type of carbohydrate and its digestibility profoundly shape the behavioural and physiological responses to protein dilution, modulate nutrient processing in the liver and alter the gut microbiota. Low (10%)-protein, high (70%)-carbohydrate diets promote the healthiest metabolic outcomes when carbohydrate comprises resistant starch (RS), yet the worst outcomes were with a 50:50 mixture of monosaccharides fructose and glucose. Our findings could explain the disparity between healthy, high-carbohydrate diets and the obesogenic impact of protein dilution by glucose-fructose mixtures associated with highly processed diets.

Chemical components and chain-length distributions affecting quinoa starch digestibility and gel viscoelasticity after germination treatment

A germination treatment was explored in this study as a green strategy to reduce the in vitro starch digestibility of cooked quinoa. The alterations of chemical compositions, starch chain-length distributions (CLDs) and rheological characteristics of quinoa flours after the germination treatment were characterized. Results showed that a significant alteration of amylose CLDs and the starch digestibility was observed for cooked quinoa flours after different germination times. By fitting starch digestograms to the logarithm of slop (LOS) plot and the combination of parallel and sequential kinetics model (CPS), two starch digestible fractions with distinct rate constants were identified. Pearson correlation analysis further found that the observed starch digestive characteristics could be largely explained by the alterations of amylose CLDs caused by the germination treatment. More specifically, the rapidly digestible starch fraction mainly consisted of amorphous amylopectin molecules and amylose intermolecular crystallites. On the other hand, the slowly digestible starch fraction was largely formed by intramolecular interactions among amylose short chains (degree of polymerization (DP) < 500). These results suggest that germination may be a promising way to develop cereal products with slower starch digestibility.

Health beneficial effects of resistant starch on diabetes and obesity via regulation of gut microbiota: a review

Resistant starch (RS) is well known to prevent type 2 diabetes mellitus (T2DM) and obesity. Recently, attention has been paid to gut microbiota which mediates the RS's impact on T2DM and obesity, while a mechanistic understanding of how RS prevents T2DM and obesity through gut microbiota is not clear yet. Therefore, this review aims at exploring the underlying mechanisms of it. RS prevents T2DM and obesity through gut microbiota by modifying selective microbial composition to produce starch-degrading enzymes, promoting the production of intestinal metabolites, and improving gut barrier function. Therefore, RS possessing good functional features can be used to increase the fiber content of healthier food. Furthermore, achieving highly selective effects on gut microbiota based on the slight differences of RS's chemical structure and focusing on the effects of RS on strain-levels are essential to manipulate the microbiota for human health.

Reanalysis of the Mars500 experiment reveals common gut microbiome alterations in astronauts induced by long-duration confinement

Maintaining astronaut health throughout long-duration spaceflight is essential to the feasibility of a manned mission to Mars. The ground-based Mars500 experiment investigated long-duration health by isolating six astronauts for 520 days, the longest controlled human confinement study conducted to date. After 520 days, astronauts had uniform strength and lean body mass losses, and increased fasting plasma glucose, calprotectin, and neutrophil levels characteristic of intestinal inflammation but previous analyses revealed no common significant changes in gut microbiota. This study reanalysed data from early (days 7–45) and late (days 420–520) faecal samples and identified 408 exact sequence variants (ESVs), including 213 shared by all astronauts. Thirty-two ESVs were significantly differentially abundant over time, including depletion of keystone resistant starch degrading, anti-inflammatory and insulin sensitivity-associated species, such as Faecalibacterium prausnitzii, Ruminococcus bromii, Blautia luti, Anaerostipes hadrus, Roseburia faecis, and Lactobacillus rogosae, and enrichment of yet-to-be-cultured bacteria. Additionally, the extraordinary experimental confinement allowed observation of microbiota potentially shared between astronauts and their habitat. Forty-nine species were shared, representing 49% and 12% of the human and environmental microbiome diversity, respectively. These findings reveal the microbiota which significantly altered in relative abundance throughout confinement, including species known to influence inflammation and host glucose homeostasis consistent with astronaut symptoms. Identification of microbiome alterations after 520 days of isolation represents a missing piece connecting Mars500 astronaut physiological studies. Knowledge of the impact of long-term confinement upon the human microbiome helps to improve our understanding of how humans interact with their habitats and is a valuable step forward towards enabling long-duration spaceflight.

Macronutrient Determinants of Obesity, Insulin Resistance and Metabolic Health

Obesity caused by the overconsumption of calories has increased to epidemic proportions. Insulin resistance is often associated with an increased adiposity and is a precipitating factor in the development of cardiovascular disease, type 2 diabetes, and altered metabolic health. Of the various factors contributing to metabolic impairments, nutrition is the major modifiable factor that can be targeted to counter the rising prevalence of obesity and metabolic diseases. However, the macronutrient composition of a nutritionally balanced "healthy diet" are unclear, and so far, no tested dietary intervention has been successful in achieving long-term compliance and reductions in body weight and associated beneficial health outcomes. In the current review, we briefly describe the role of the three major macronutrients, carbohydrates, fats, and proteins, and their role in metabolic health, and provide mechanistic insights. We also discuss how an integrated multi-dimensional approach to nutritional science could help in reconciling apparently conflicting findings.

Circulating GLP-1 Levels as a Potential Indicator of Metabolic Syndrome Risk in Adult Women

Glucagon-like peptide-1 (GLP-1), an incretin hormone, plays an important role in regulating glucose homeostasis. In this study, the applicability of circulating GLP-1 levels as an early indicator of metabolic syndrome (MetS) risk was examined. Women without diagnosed diseases were grouped according to their number of MetS risk factors (MetS RFs) (no RFs as Super-healthy, n = 61; one or two RFs as MetS risk carriers, n = 60; 3 ≤ RFs as MetS, n = 19). The circulating GLP-1 levels and homeostasis model assessment insulin resistance (HOMA-IR) scores were significantly higher in the MetS group than in the other two groups. The GLP-1 levels correlated positively with adiposity, HOMA-IR, blood pressure, and high sensitivity C-reactive protein (hs-CRP), but not with fasting glucose and lipid profiles, whose significances were maintained after adjustments for age, smoking and drinking habits, menopausal status, and total calorie intake. The GLP-1 levels also increased proportionally with the number of MetS RFs. In the MetS group, the GLP-1 levels were much higher in individuals with obesity (body mass index ≥ 25 kg/m²). In conclusion, the circulating GLP-1 level may be applicable as a potential early indicator of MetS risk in women without diagnosed diseases. Further study with a large population is needed to confirm the conclusion.

Metabolic Responses to Native Wheat Starch (MidsolTM 50) versus Resistant Wheat Starch Type 4 (Fibersym® RW): Standard versus Marketplace Testing Protocols

BACKGROUND

To investigate the effect of resistant starch (RS) on acute glycemic or insulinemic responses, the FDA indicates that control and RS-enriched foods must contain equivalent amounts of digestible carbohydrate. However, RS-containing foods typically contain less digestible carbohydrate per serving than control foods. Thus, controlling for digestible carbohydrate may yield different responses as compared with controlling for serving size.

OBJECTIVE

The aim was to compare the postprandial metabolic responses to native wheat starch (NWS) versus RS type 4 (RS4) using digestible carbohydrate-matched portions compared with weight-matched portions.

METHODS

A single-blind, randomized-controlled crossover trial examined glycemic and insulinemic responses over 2 h following consumption of 4 cracker conditions and a dextrose beverage in apparently healthy participants (n = 14). Crackers provided 50 g of digestible carbohydrate using the FDA's meal-intervention protocol or 35 g of carbohydrate by weight for the marketplace substitution method. Crackers differed only by the type of starch additive: NWS (MidsolTM 50; MGP Ingredient, Inc.) or RS4 (Fibersym® RW; MGP Ingredients, Inc.). Glucose concentrations were assessed at baseline and at 15, 30, 45, 60, 90, and 120 min; insulin concentrations were measured at baseline and 30, 60, and 120 min.

RESULTS

There were no significant differences between 50 g digestible carbohydrate cracker conditions for glucose or insulin incremental AUC (iAUC). The 35 g carbohydrate by weight conditions were not different for glucose iAUC [mean (95% CI): 35 g NWS: 1317 (677, 2169); 35 g RS4: 701 (262, 1351); P > 0.05]. However, insulin iAUC was lower following 35 g RS4 compared with 35 g NWS [35 g RS4: 92 (1, 259); 35 g NWS: 697 (397, 1080); P < 0.01].

CONCLUSIONS

In healthy adults, consumption of RS4 crackers decreased postprandial insulin responses compared with NWS crackers when using the marketplace substitution method compared with the FDA standard testing method, with similar postprandial glucose responses. Comparisons of the FDA standard testing method and the marketplace substitution method should be investigated further to elucidate differential physiological impacts on consumers.

Effect of Dietary Acetic Acid Supplementation on Plasma Glucose, Lipid Profiles, and Body Mass Index in Human Adults: A Systematic Review and Meta-analysis

BACKGROUND

Acetic acid is a short-chain fatty acid that has demonstrated biomedical potential as a dietary therapeutic agent for the management of chronic and metabolic illness comorbidities. In human beings, its consumption may improve glucose regulation and insulin sensitivity in individuals with cardiometabolic conditions and type 2 diabetes mellitus. Published clinical trial evidence evaluating its sustained supplementation effects on metabolic outcomes is inconsistent.

OBJECTIVE

This systematic review and meta-analysis summarized available evidence on potential therapeutic effects of dietary acetic acid supplementation via consumption of acetic acid-rich beverages and food sources on metabolic and anthropometric outcomes.

METHODS

A systematic search was conducted in Medline, Scopus, EMBASE, CINAHL Plus, and Web of Science from database inception until October 2020. Randomized controlled trials conducted in adults evaluating the effect of dietary acetic acid supplementation for a minimum of 1 week were included. Meta-analyses were performed using a random-effects model on fasting blood glucose (FBG), triacylglycerol (TAG), high-density lipoprotein (HDL), low-density lipoprotein (LDL), glycated hemoglobin (HbA1c), body mass index (BMI), and body fat percentage. Statistical heterogeneity was assessed by calculation of Q and I² statistics, and publication bias was assessed by calculation of Egger's regression asymmetry and Begg's test.

RESULTS

Sixteen studies were included, involving 910 participants who consumed between 750 and 3600 mg acetic acid daily in interventions lasting an average of 8 weeks. Dietary acetic acid supplementation resulted in significant reductions in TAG concentrations in overweight and obese but otherwise healthy individuals (mean difference [MD] = -20.51 mg/dL [95% confidence intervals = -32.98, -8.04], P = .001) and people with type 2 diabetes (MD = -7.37 mg/dL [-10.15, -4.59], P < .001). Additionally, acetic acid supplementation significantly reduced FBG levels (MD = -35.73 mg/dL [-63.79, -7.67], P = .01) in subjects with type 2 diabetes compared with placebo and low-dose comparators. No other changes were seen for other metabolic or anthropometric outcomes assessed. Five of the 16 studies did not specify the dose of acetic acid delivered, and no studies measured blood acetate concentrations. Only one study controlled for background acetic acid-rich food consumption during intervention periods. Most studies had an unclear or high risk of bias.

CONCLUSION

Supplementation with dietary acetic acid is well tolerated, has no adverse side effects, and has clinical potential to reduce plasma TAG and FBG concentrations in individuals with type 2 diabetes, and to reduce TAG levels in people who are overweight or obese. No significant effects of dietary acetic acid consumption were seen on HbA1c, HDL, or anthropometric markers. High-quality, longer-term studies in larger cohorts are required to confirm whether dietary acetic acid can act as an adjuvant therapeutic agent in metabolic comorbidities management.

Causal relations among starch fine molecular structure, lamellar/crystalline structure and in vitro digestion kinetics of native rice starch

Causal relations among starch fine molecular structures, lamellar/crystalline structures, and the in vitro digestion kinetics of native rice starches.

Differences in Capacity of High-Amylose Resistant Starch, Whole-Grain Flour, and a Combination of Both to Modify Intestinal Responses of Male Sprague Dawley Rats Fed Moderate and High Fat Diets

Gastrointestinal tract (GIT) responses to a high-amylose resistant starch (RS) product were compared to those observed when RS was combined with whole grain (WG) and to controls with low RS intake in rats fed moderate or high fat diets. Regardless of fat intake, rats fed RS or WG + RS diets had higher cecum weights, higher intestinal quantities of short chain fatty acids, and lower intestinal content pH, and their GIT cells had increased gene expression for gluconeogenesis and barrier function compared to controls. Whereas RS resulted in greater GIT content acetate and propionate and lowest pH, the WG + RS diets yielded higher butyrate. Rats fed the RS diet with MF had higher cecum weights than those fed either the RS diet with HF or the WG + RS diet with either MF or HF. Diets containing combinations of RS and other dietary fibers should be considered for RS-mediated GIT benefits.

Starch digestibility: past, present, and future

In the last century, starch present in foods was considered to be completely digested. However, during the 1980s, studies on starch digestion started to show that besides digestible starch, which could be rapidly or slowly hydrolysed, there was a variable fraction that resisted hydrolysis by digestive enzymes. That fraction was named resistant starch (RS) and it encompasses those forms of starch that are not accessible to human digestive enzymes but can be fermented by the colonic microbiota, producing short-chain fatty acids. RS has been classified into five types, depending on the mechanism governing its resistance to enzymatic hydrolysis. Early research on RS was focused on the methods to determine its content in foods and its physiological effects, including fermentability in the large intestine. Later on, due to the interest of the food industry, methods to increase the RS content of isolated starches were developed. Nowadays, the influence of RS on the gut microbiota is a relevant research topic owing to its potential health-related benefits. This review summarizes over 30 years of investigation on starch digestibility, its relationship with human health, the methods to produce RS and its impact on the microbiome. © 2018 Society of Chemical Industry.

Effects of potato resistant starch intake on insulin sensitivity, related metabolic markers and appetite ratings in men and women at risk for type 2 diabetes: a pilot cross-over randomised controlled trial

Background

The intake of certain types of resistant starch (RS) has been associated in some studies with increased whole‐body insulin sensitivity. This randomised, cross‐over pilot trial evaluated the effect of consuming cooked, then chilled potatoes, a source of RS, compared to isoenergetic, carbohydrate (CHO)‐containing control foods, on insulin sensitivity and related markers.

Methods

Nineteen adults with body mass index 27.0‐39.9 kg m⁻² consumed 300 g day⁻¹ RS‐enriched potatoes (approximately two potatoes; ~18 g RS) or CHO‐based control foods, as part of lunch, evening and snack meals, over a 24‐h period. After an overnight fast, insulin sensitivity, CHO metabolism markers, free fatty acids, breath hydrogen levels and appetite were assessed for up to 5 h after the intake of a standard breakfast. The primary endpoint was insulin sensitivity, assessed with the Matsuda index. P < 0.05 (one‐sided) was considered statistically significant.

Results

Insulin sensitivity was not significantly different between the potato and control conditions. The potato intervention resulted in higher postprandial breath hydrogen (P = 0.037), lower postprandial free fatty acid concentrations (P = 0.039) and lower fasting plasma glucose (P = 0.043) compared to the control condition. Fullness ratings were significantly lower after potato versus control (P = 0.002). No other significant effects were observed; however, there was a trend toward lower fasting insulin (P = 0.077) in the potato versus the control condition.

Conclusions

The results of this pilot study suggest RS‐enriched potatoes may have a favourable impact on carbohydrate metabolism and support the view that additional research in a larger study sample is warranted.

Effect of resistant starch type 2 on inflammatory mediators: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

Inflammation is the main cause in the development of chronic diseases. The enhancement of pro-inflammatory factors, such as tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and high-sensitivity C-reactive protein (hs-CRP) is the main risk factor in chronic diseases. Resistant starch type 2 (RS2) is non-gelatinized granules which their enzymatic hydrolysis is very low. RS2 might be able to reduce inflammatory mediators, therefore; our aim for this study was indicating RS2 effects on inflammatory mediators such as IL-6, TNF-a, and CRP among healthy and unhealthy subjects.

METHODS

Articles which assessed RS2 effect on IL-6, TNF-α, and hs-CRP were found by advanced search methods. Electronic databases including Google scholar, ISI web of science, SCOPUS, and PubMed, were searched up to October 2019. Treatment effect was the mean difference between changes in serum levels of inflammatory biomarkers in each arm of the clinical trials. To pool the effect of resistant starch on inflammatory biomarkers, we used random effects model.

RESULTS

We included eight articles in systematic review and meta-analysis. The overall effect illustrated no significant change in serum levels of hs-CRP, IL-6, and TNF-α in intervention group compared with the control group (WMD: -7.18 pg/mL, 95% CI: -27.80, 13.45; P = 0.495, I² = 100.0%, WMD: -0.003 pg/mL, 95% CI: -0.07, 0.06; P = 0.919, I² = 98.1%, WMD: -0.003 pg/mL, 95% CI: -0.004, -0.001; P < 0.0001, I² = 98.0% respectively).

CONCLUSION

In conclusion, we found that RS2 could not reduce inflammatory mediators, but we still need more RCTs with longer intervention duration, higher dose, and studies in different countries.

Effects of resistant starch on glycaemic control: a systematic review and meta-analysis

The effects of resistant starch on glycaemic control are controversial. In this study, a systematic review and meta-analysis of results from nineteen randomised controlled trials (RCT) was performed to illustrate the effects of resistant starch on glycaemic control. A literature search was conducted on PubMed, Scopus and Cochrane electronic databases for related publications from inception to 6 April 2020. Key inclusion criteria were: RCT; resistant starch as intervention substances and reporting glucose- and insulin-related endpoints. Exclusion criteria were: using type I resistant starch or a mixture of resistant starch and other functional food ingredients as intervention; using substances other than digestible starch as controls. The effect of resistant starch on fasting plasma glucose was significant (effect size (ES) –0·09 (95 % CI –0·13, −0·04) mmol/l, P = 0·001) compared with digestible starch. Subgroup analyses revealed that the ES was larger when the dosage of resistant starch was more than 28 g/d (ES –0·16 (95 % CI –0·24, –0·08) mmol/l, P < 0·001) or the intervention period was more than 8 weeks (ES –0·12 (95 % CI –0·18, –0·06) mmol/l, P < 0·001). The effect on homoeostatic model assessment (HOMA)-insulin resistance (IR) was significant (ES –0·33 (95 % CI –0·51, –0·14), P = 0·001). However, the effects on other insulin-related endpoints were not significant, including fasting plasma insulin, four endpoints from the frequently sampled intravenous glucose tolerance test (insulin sensitivity index, acute insulin response, disposition index and glucose effectiveness) and HOMA-β. The current study indicated moderate effects of resistant starch on improving glycaemic control.

Production and Properties of Starch Citrates-Current Research

Starch modification by chemical reaction is widely used to improve the properties of native starch. Modified by citric acid, starch is characterized by specific properties resulting from the presence of citrate residues and as a result of cross-linking starch. The chemicals used for preparing starch citrates are safe for human health and the natural environment compared to the harsh chemicals used for conventional modifications. Starch citrates are traditionally produced by heating starch-citric acid mixtures in semi-dry conditions or by a heat moisture treatment. The conditions of the modification process (roasting temperature, heating time, citric acid dose) and the botanic source or genotype of starch determine the degree of substitution and the properties of the obtained preparations. Changes of starch properties occurring during esterification lead to reduced relative crystallinity, resulting in a decrease in the affinity for water, the gelatinization parameters, and the viscosity of starch citrate. However, one of the most important outcome of the modification is the formation of resistant starch (RS), which has increased resistance to the action of amylolytic enzymes. Currently, new methods for producing starch citrates with improved functional and rheological properties while maintaining the highest possible content of resistant starch are being sought. The article presents an overview of recent studies on the production, properties. And applicability of starch citrates with special attention paid to their role as preparations of resistant starch (RS). The use of citric acid for modification of starch is better for the technology process, while using cross-linking is better than simply using esterification.

Potato Preload Mitigated Postprandial Glycemic Excursion in Healthy Subjects: An Acute Randomized Trial

This study investigated the preload effect of the medium and high glycemic index (GI) potato, as well as the combination of partially hydrolyzed guar gum (HG) and potato, when ingested prior to a rice meal, on the iso-carbohydrate basis. In a randomized crossover trial, 17 healthy female subjects consumed (1) rice; (2) co-ingestion of highly cooked potato (HP), and rice (HP + R); (3) co-ingestion of minimally cooked potato (MP) and rice (MP + R); (4) preload HP prior to rice meal (PHP + R); (5) preload MP prior to rice meal (PMP + R); (6) co-ingestion of partially hydrolyzed guar gum (HG), HP and rice (HG + HP + R); (7) preload HG prior to co-ingestion of HP and rice (PHG + HP + R); (8) co-preload of HG and HP prior to rice (PHG + PHP + R); and (9) preload of HP prior to co-ingestion of HG and rice (PHP + HG + R). Postprandial glycemic response (GR) tests and subjective satiety tests were conducted for each test food. Cooked potato as a preload to a rice meal could significantly cut the acute postprandial glycemic excursion by around 1.0 mmol/L, irrespective of the GI of the preload. Co-preload of partial hydrolyzed guar gum and highly cooked potato (PHG + PHP + R) resulted in improved acute GR in terms of peak glucose value and glycemic excursion compared with either HG preload or HP preload. All the meals with preload showed comparable or improved self-reported satiety. Within an equicarbohydrate exchange framework, both high-GI and medium-GI potato preload decreased the postprandial glycemic excursion in young healthy female subjects. The combination of HG and HP as double preload resulted in better GR than both single HG or HP preload did.

Effect of steam explosion on nutritional composition and antioxidative activities of okra seed and its application in gluten-free cookies

Health-conscious consumers are increasingly interested in gluten-free (GF) foods. Raw okra seed (ROS) flour and steam-exploded okra seed (SEOS) flour were explored for developing GF cookies with high nutritional values and in vitro enzymatic digestion. Results indicated that the steam explosion exhibited significant effects on enhancing the release of dietary fibers and lipids in okra seed flour at moderate explosion pressure. Although steam explosion caused the loss of flavonoid compounds, moderate high explosion pressure enhanced the release of total phenolics ranged from 294.57 to 619.07 mg GAE/100 g DM with significantly improved DPPH• radical scavenging activity (from 18.78% to 67.34%) and ferric reducing antioxidant power (from 13.37% to 149.04%). The rapidly digestible starch (RDS) content in GF cookies decreased with increasing steam explosion severity, whereas slowly digestible starch (SDS) and resistant starch (RS) contents significantly increased from 36.91% to 40.92% and from 2.50% to 9.06%, respectively. Steam explosion is an effective technique for enhancing the release of nutrients like dietary fiber and total phenolics, and okra seed flour, especially SEOS flour, can be alternative choices to provide food functional materials for developing various GF food products.

Glucose and lipid metabolism of broiler chickens fed diets with graded levels of corn resistant starch

1. The aim of this study was to investigate the effects of graded levels of dietary corn resistant starch (RS) on glucose and lipid metabolism of broilers. 2. A total of 320 male broiler chicks (Arbor Acres, one-day-old) were randomly allocated to five dietary treatments, including a corn-soybean control diet, a corn-soybean based diet containing 20% corn starch, and three diets containing 4%, 8% and 12% RS by replacing corn starch with 6.67%, 13.33% and 20% Hi-Maize® 260 (identified as control, RS1, RS2, RS3 and RS4, respectively). Each treatment contained eight replicates with eight birds, and the experiment lasted 42 days. 3. Birds fed RS diets showed lower (P < 0.05) concentrations of serum low-density lipoprotein cholesterol and non-esterified fatty acid (NEFA) at d 21 and 42 of age, compared to the control. Lower (P < 0.05) hepatic apolipoprotein B concentration and citrate synthase (CS) activity, as well as a higher (P < 0.05) glycogen synthase (GS) concentration were observed in birds fed RS diets than those in the control group at d 21 of age. Consuming RS diets linearly increased (P < 0.01) serum glucose concentration, and linearly decreased (P < 0.01) NEFA concentrations in broilers at d 21 and 42 of age. Liver GS concentration and activities of hexokinase, pyruvate and CS were linearly increased (P < 0.01) in broilers at d 21 of age, but were linearly decreased (P < 0.05) in birds at d 42 of age in response to the increase of dietary RS levels. Feeding RS diets linearly decreased (P < 0.05) mRNA expressions of PC, PPARα and CPT-1 at d 21 of age and the mRNA expressions of SREBP-1 c, ChREBP, ACC and FAS at d 42 of age, and linearly increased (P < 0.05) the mRNA expressions of PEPCK, PC, LKB1, AMPKα1, PPARα, CPT-1 and L-FABP at d 42 of age. 4. Feeding broilers with diets containing higher concentration of RS promoted hepatic lipolysis and gluconeogenesis through activated AMPK signalling pathway and accelerated whole-body energy expenditures in the grower phase.

A specific gut microbiota and metabolomic profiles shifts related to antidiabetic action: The similar and complementary antidiabetic properties of type 3 resistant starch from Canna edulis and metformin

The relationship between gut microbiota and type 2 diabetes mellitus (T2DM) has drawn increasing attention, and the benefits of various treatment strategies, including nutrition, medication and physical exercise, maybe microbially-mediated. Metformin is a widely used hypoglycemic agent, while resistant starch (RS) is a novel dietary fiber that emerges as a nutritional strategy for metabolic disease. However, it remains unclear as to the potential degree and interactions among gut microbial communities, metabolic landscape, and the anti-diabetic effects of metformin and RS, especially for a novel type 3 resistant starch from Canna edulis (Ce-RS3). In the present study, T2DM rats were administered metformin or Ce-RS3, and the changes in gut microbiota and serum metabolic profiles were characterized using 16S-rRNA gene sequencing and metabolomics, respectively. After 11 weeks of treatment, Ce-RS3 exhibited similar anti-diabetic effects to those of metformin, including dramatically reducing blood glucose, ameliorating the response to insulin resistance and glucose tolerance test, and relieving the pathological damage in T2DM rats. Interestingly, the microbial and systemic metabolic dysbiosis in T2DM rats was effectively modulated by both Ce-RS3 and, to a lesser extent, metformin. The two treatments increased the gut bacterial diversity, and supported the restoration of SCFA-producing bacteria, thereby significantly increasing SCFAs levels. Both treatments simultaneously corrected 16 abnormal metabolites in the metabolism of lipids and amino acids, many of which are microbiome-related. PICRUSt analysis and correlation of SCFAs levels with metabolomics data revealed a strong association between gut microbial and host metabolic changes. Strikingly, Ce-RS3 exhibited better efficacy in increasing gut microbiota diversity with a peculiar enrichment of Prevotella genera. The gut microbial properties of Ce-RS3 were tightly associated with the T2DM-related indexes, showing the potential to alleviate diabetic phenotype dysbioses, and possibly explaining the greater efficiency in improving metabolic control. The beneficial effects of Ce-RS3 and metformin might derive from changes in gut microbiota through altering host-microbiota interactions with impact on the host metabolome. Given the complementarity of Ce-RS3 and metformin in regulation of gut microbiota and metabolites, this study also prompted us to suggest possible "Drug-Dietary fiber" combinations for managing T2DM.

Targeting Glycoproteins as a therapeutic strategy for diabetes mellitus and its complications

OBJECTIVES

Glycoproteins are organic compounds formed from proteins and carbohydrates, which are found in many parts of the living systems including the cell membranes. Furthermore, impaired metabolism of glycoprotein components plays the main role in the pathogenesis of diabetes mellitus. The aim of this study is to investigate the influence of glycoprotein levels in the treatment of diabetes mellitus.

METHODS

All relevant papers in the English language were compiled by searching electronic databases, including Scopus, PubMed and Cochrane library. The keywords of glycoprotein, diabetes mellitus, glycan, glycosylation, and inhibitor were searched until January 2019.

RESULTS

Glycoproteins are pivotal elements in the regulation of cell proliferation, growth, maturation and signaling pathways. Moreover, they are involved in drug binding, drug transportation, efflux of chemicals and stability of therapeutic proteins. These functions, structure, composition, linkages, biosynthesis, significance and biological effects are discussed as related to their use as a therapeutic strategy for the treatment of diabetes mellitus and its complications.

CONCLUSIONS

The findings revealed several chemical and natural compounds have significant beneficial effects on glycoprotein metabolism. The comprehension of glycoprotein structure and functions are very essential and inevitable to enhance the knowledge of glycoengineering for glycoprotein-based therapeutics as may be required for the treatment of diabetes mellitus and its associated complications. Graphical abstract.

Improving nutritional quality of rice for human health

This review surveys rice nutritional value, mainly focusing on breeding achievements via adoption of both genetic engineering and non-transgenic strategies to improve key nutrients associated with human health. Rice (Oryza sativa) is an essential component of the diets and livelihoods of over 3.5 billion people. Polished rice is mostly consumed as staple food, fulfilling daily energy demands and part of the protein requirement. Brown rice is comparatively more nutritious, containing more lipids, minerals, vitamins, dietary fiber, micronutrients, and bioactive compounds. In this article, we review the nutritional facts about rice including the level of γ-aminobutyric acid, resistant starch, lysine, iron, zinc, β-carotene, folate, anthocyanin, various carotenoids, and flavonoids, focusing on their synthesis and metabolism and the advances in their biofortification via adoption of both conventional and genetic engineering strategies. We conclude that besides representing a staple food, rice has the potential to become a source of various essential nutrients or bioactive compounds through appropriate genetic improvements to benefit human health and prevent certain chronic diseases. Finally, we discuss the available, non-genetically engineering strategies for the nutritional improvement of rice, including their main strengths and constraints.

Comparison of utilisation and fermentation of highly cross-linked phosphate starches produced from two different plant origins, potato and tapioca in rats and humans

The utilisation and fermentation of highly cross-linked phosphate starches made from two different origins, potato (HXL-P) and tapioca (HXL-T) were investigated in rats and humans. HXL-P and HXL-T were highly resistant to digestion by carbohydrate enzymes and were also resistant to fermentation by gut microbiota in rats. The postprandial blood glucose scarcely increased after administration of HXL-P or HXL-T in healthy humans. Incremental AUC of both HXL-P and HXL-T for 180 min was significantly lower than that of glucose (p < .05). Breath hydrogen excretion was very low after oral administration of HXL-P or HXL-T, and AUCs of breath hydrogen excretion for 13 h after administration were significantly lower than that of fructooligosaccharide as a reference of fermentation (p < .05). These results show that HXL-P and HXL-T were hardly digested and were highly resistant to fermentation. In conclusion, HXL-P and HXL-T could be good low-energy bulking ingredients to replace wheat flour.

Impact of dietary intake of resistant starch on obesity and associated metabolic profiles in human: a systematic review of the literature

As a global public health issue with an increasing prevalence, obesity is related to several metabolic disorders, but is largely preventable. Resistant starch (RS), the indigestible portion of starch, has been studied for its potential effects on reducing obesity. This systematic review aimed to investigate the effect of dietary intake of RS on obesity development and related metabolic profiles in human, including body weight and composition, energy intake and satiety, lipid profiles, blood glucose and insulin, and other blood biomarkers. Eleven peer-reviewed articles published in English between 2000 and 2019 were identified after screening using CENTRAL, MEDLINE, and CINAHL Plus. Based on the results, RS intake had no direct effect on body weight and body composition. Evidence for its effect on reducing energy intake and increasing satiety, as well as improving lipid profiles was inconsistent. Beneficial effects of RS intake on several blood biomarkers were supported, indicating its regulatory roles in blood glucose homeostasis, insulin sensitivity, and gut hormone concentrations. Specifically, five out of the eight articles measuring blood glucose reported a decrease in either fasting or postprandial glucose levels; two out of the three articles measuring insulin sensitivity indicated a significant improvement after RS supplementation; studies measuring gut hormone concentrations including glucagon-like peptide 1 (GLP-1), and peptide YY (PYY) also showed significant improvements after RS interventions. In conclusion, the effect of dietary intake of RS on obesity and its related metabolic complications was not conclusive. Further research with larger sample sizes and longer duration is warranted.

Resistant Starch Has No Effect on Appetite and Food Intake in Individuals with Prediabetes

BACKGROUND

Type 2 resistant starch (RS2) has been shown to improve metabolic health outcomes and may increase satiety and suppress appetite and food intake in humans.

OBJECTIVE

This study assessed whether 12 weeks of daily RS2 supplementation could influence appetite perception, food intake, and appetite-related gut hormones in adults with prediabetes, relative to the control (CTL) group.

DESIGN

The study was a randomized controlled trial and analysis of secondary study end points.

PARTICIPANTS/SETTING

Sixty-eight adults (body mass index ≥27) aged 35 to 75 years with prediabetes were enrolled in the study at Pennington Biomedical Research Center (2012 to 2016). Fifty-nine subjects were included in the analysis.

INTERVENTION

Participants were randomized to consume 45 g/day of high-amylose maize (RS2) or an isocaloric amount of the rapidly digestible starch amylopectin (CTL) for 12 weeks.

MAIN OUTCOME MEASURES

Subjective appetite measures were assessed via visual analogue scale and the Eating Inventory; appetite-related gut hormones (glucagon-like peptide 1, peptide YY, and ghrelin) were measured during a standard mixed-meal test; and energy and macronutrient intake were assessed by a laboratory food intake (buffet) test, the Remote Food Photography Method, and SmartIntake app.

STATISTICAL ANALYSES PERFORMED

Data were analyzed using linear mixed models, adjusting for treatment group and time as fixed effects, with a significance level of α=.05.

RESULTS

RS2 had no effect on subjective measures of appetite, as assessed by visual analogue scale (P>0.05) and the Eating Inventory (P≥0.24), relative to the CTL group. There were no effects of RS2 supplementation on appetite-related gut hormones, including glucagon-like peptide 1 (P=0.61), peptide YY (P=0.34), and both total (P=0.26) and active (P=0.47) ghrelin compared with the CTL. RS2 had no effect on total energy (P=0.30), carbohydrate (P=0.11), protein (P=0.64), or fat (P=0.37) consumption in response to a buffet meal test, relative to the CTL. In addition, total energy (P=0.40), carbohydrate (P=0.15), protein (P=0.46), and fat (P=0.53) intake, as quantified by the Remote Food Photography Method, were also unaffected by RS2, relative to the CTL.

CONCLUSIONS

RS2 supplementation did not increase satiety or reduce appetite and food intake in adults with prediabetes.

Fresh Saengshik Showed a Positive Effect on Mitigating Dextran Sulfate Sodium-Induced Experimental Colitis in Mice

This study was to compare the anticolitis activity of fresh Saengshik (FSS) with heated Saengshik (HSS) with dextran sulfate sodium (DSS)-induced experimental colitis mouse model. Both FSS- and HSS-fed colitis mice exhibited the effects of the increase in the body weight, the alleviation in the colon shortening, and the reduction of the ratio of colon weight to length. However, FSS-fed colitis mice showed a much more significant decrease in DSS-induced tissue damage by mucosal edema and crypt deficiency than did HSS-fed ones. Besides, FSS contributed to decreasing the serum levels of proinflammatory cytokines (tumor necrosis factor-alpha and interleukin-1 beta) and inhibiting the colonic mRNA expressions of these cytokines in colitis tissue of the mice. FSS also resulted in the lower colonic mRNA expression level of inflammation-related inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) in colitis mice than did HSS. Overall results confirmed Saengshik, especially FSS, inhibits more effectively against DSS-induced inflammation reaction in colitis mice than HSS.

Resistant starch supplementation attenuates inflammation in hemodialysis patients: a pilot study

PURPOSE

In chronic kidney disease (CKD) patients, dysbiosis is associated with inflammation and cardiovascular risk, so many nutritional strategies are being studied to reduce these complications. Resistant starch (RS) can be considered a prebiotic that promotes many benefits, including modulation of gut microbiota which is linked to immune-modulatory effects. The aim of this study was to evaluate the effects of RS supplementation on proinflammatory cytokines in CKD patients on hemodialysis (HD).

METHODS

A double-blind, placebo-controlled, randomized trial was conducted with sixteen HD patients (55.3 ± 10.05 years, body mass index (BMI) 25.9 ± 5.42 kg/m², 56% men, time on dialysis 38.9 ± 29.23 months). They were allocated to the RS group (16 g RS/day) or placebo group (manioc flour). The serum concentration of ten cytokines and growth factors was detected through a multiparametric immunoassay based on XMap-labeled magnetic microbeads (Luminex Corp, USA) before and after 4 weeks with RS supplementation.

RESULTS

After RS supplementation, there was a reduction of Regulated upon Activation, Normal T-Cell Expressed and Secreted (p < 0.001), platelet-derived growth factor (two B subunits) (p = 0.014) and interferon-inducible protein 10 (IP-10) (p = 0.027). The other parameters did not change significantly.

CONCLUSION

This preliminary result indicates that RS may contribute to a desirable profile of inflammatory markers in CKD patients.

The Role of Short-Chain Fatty Acids From Gut Microbiota in Gut-Brain Communication

A substantial body of evidence supports that the gut microbiota plays a pivotal role in the regulation of metabolic, endocrine and immune functions. In recent years, there has been growing recognition of the involvement of the gut microbiota in the modulation of multiple neurochemical pathways through the highly interconnected gut-brain axis. Although amazing scientific breakthroughs over the last few years have expanded our knowledge on the communication between microbes and their hosts, the underpinnings of microbiota-gut-brain crosstalk remain to be determined. Short-chain fatty acids (SCFAs), the main metabolites produced in the colon by bacterial fermentation of dietary fibers and resistant starch, are speculated to play a key role in neuro-immunoendocrine regulation. However, the underlying mechanisms through which SCFAs might influence brain physiology and behavior have not been fully elucidated. In this review, we outline the current knowledge about the involvement of SCFAs in microbiota-gut-brain interactions. We also highlight how the development of future treatments for central nervous system (CNS) disorders can take advantage of the intimate and mutual interactions of the gut microbiota with the brain by exploring the role of SCFAs in the regulation of neuro-immunoendocrine function.

Short chain fatty acids could prevent fat deposition in pigs via regulating related hormones and genes

Short chain fatty acids (SCFAs) are produced when indigestible carbohydrates, such as fiber and resistant starch, undergo fermentation by specific microbiota in the hindgut.

Novel Resistant Starch Type 4 Products of Different Starch Origins, Production Methods, and Amounts Are Not Equally Fermented when Fed to Sprague-Dawley Rats

SCOPE

The possible mechanisms of production of four novel resistant starch type 4 (RS4) products for total cecal fermentation in an in vivo rodent model are evaluated.

METHODS AND RESULTS

Forty weanling rats are randomly assigned to five groups (n = 8) for a 3-week study. Starches are the RS type 4 products, as 10% of weight of RS diets (RSA-RSD), and AMIOCA starch (100% amylopectin) comprises 53.6% weight of control (CON) and 43.6% weight of RS diets. The RS products vary by percent purity and origin (potato, corn, tapioca). At euthanasia, cecal contents, serum, GI tract, and abdominal fat are collected. RSB, RSC, and RSD fed rats have greater empty cecum weights, lower cecal content pH, higher cecal content wet weight, and higher total cecal content acetate and propionate than the CON and RSA fed rats. Two other indicators of fermentation, total cecal contents butyrate and glucagon-like peptide 1, do not have significant ANOVA F values, which require more subjects for 80% power.

CONCLUSION

RS4 products that are produced from different starch origins with varying amounts of RS4 content and different methods of production are not uniformly fermented in an in vivo model.

What Is the Impact of Diet on Nutritional Diarrhea Associated with Gut Microbiota in Weaning Piglets: A System Review

Piglets experience severe growth challenges and diarrhea after weaning due to nutritional, social, psychological, environmental, and physiological changes. Among these changes, the nutritional factor plays a key role in postweaning health. Dietary protein, fibre, starch, and electrolyte levels are highly associated with postweaning nutrition diarrhea (PWND). In this review, we mainly discuss the high protein, fibre, resistant starch, and electrolyte imbalance in diets that induce PWND, with a focus on potential mechanisms in weaned piglets.

Cas9-mediated mutagenesis of potato starch-branching enzymes generates a range of tuber starch phenotypes

We investigated whether Cas9-mediated mutagenesis of starch-branching enzymes (SBEs) in tetraploid potatoes could generate tuber starches with a range of distinct properties. Constructs containing the Cas9 gene and sgRNAs targeting SBE1, SBE2 or both genes were introduced by Agrobacterium-mediated transformation or by PEG-mediated delivery into protoplasts. Outcomes included lines with mutations in all or only some of the homoeoalleles of SBE genes and lines in which homoeoalleles carried several different mutations. DNA delivery into protoplasts resulted in mutants with no detectable Cas9 gene, suggesting the absence of foreign DNA. Selected mutants with starch granule abnormalities had reductions in tuber SBE1 and/or SBE2 protein that were broadly in line with expectations from genotype analysis. Strong reduction in both SBE isoforms created an extreme starch phenotype, as reported previously for low-SBE potato tubers. HPLC-SEC and 1 H NMR revealed a decrease in short amylopectin chains, an increase in long chains and a large reduction in branching frequency relative to wild-type starch. Mutants with strong reductions in SBE2 protein alone had near-normal amylopectin chain-length distributions and only small reductions in branching frequency. However, starch granule initiation was enormously increased: cells contained many granules of <4 μm and granules with multiple hila. Thus, large reductions in both SBEs reduce amylopectin branching during granule growth, whereas reduction in SBE2 alone primarily affects numbers of starch granule initiations. Our results demonstrate that Cas9-mediated mutagenesis of SBE genes has the potential to generate new, potentially valuable starch properties without integration of foreign DNA into the genome.

Resistant starch ameliorated insulin resistant in patients of type 2 diabetes with obesity: a systematic review and meta-analysis

BACKGROUND

Resistant starch (RS) is a starch that can be fermented by the microbial flora within gut lumen. Insulin resistance (IR) is a pathophysiological condition related to diabetes and obesity. RS could reduce blood glucose and ameliorate IR in animals, but its effect in human population is controversial.

OBJECTIVE

The authors conducted a systematic literature review to evaluate the effect of RS diet supplement on ameliorating IR in patients with T2DM and simple obesity.

METHODS

Databases that supplemented with RS in ameliorating IR in T2DM and simple obesity were queried for studies on or before August 15, 2018. Parameters including fasting insulin, fasting glucose, body mass index (BMI), homeostatic model assessment (HOMA) etc. were extracted from studies to systemically evaluate effects of RS.

RESULTS

The database search yielded 14 parallel or crossover studies that met the inclusion criteria. The results indicated that there was no significant difference in the amelioration of BMI, HOMA-%S and HOMA-%B in T2DM patients between RS and the non-RS supplementation. However, the fasting blood glucose, fasting insulin and HOMA-IR in T2DM with obesity who supplemented RS were lower than control group, and the subgroup analysis according to the dose of RS supplementation was inconsistency. There was no significant difference between RS and non-RS supplements in patients with simple obesity.

CONCLUSION

RS supplementation can ameliorate IR in T2DM, especially for the patients of T2DM with obesity, but not in simple obesity.

Dietary administration of resistant starch improved caecal barrier function by enhancing intestinal morphology and modulating microbiota composition in meat duck

Resistant starch (RS) was recently approved to exert a powerful influence on gut health, but the effect of RS on the caecal barrier function in meat ducks has not been well defined. Thus, the effect of raw potato starch (RPS), a widely adopted RS material, on microbial composition and barrier function of caecum for meat ducks was determined. A total of 360 Cherry Valley male ducks of 1-d-old were randomly divided and fed diets with 0 (control), 12, or 24 % RPS for 35 d. Diets supplemented with RPS significantly elevated villus height and villus height:crypt depth ratio in the caecum. The 16S rRNA sequence analysis indicated that the diet with 12 % RPS had a higher relative abundance of Firmicutes and the butyrate-producing bacteria Faecalibacterium, Subdoligranulum, and Erysipelatoclostridium were enriched in all diets. Lactobacillus and Bifidobacterium were significantly increased in the 24 % RPS diet v. the control diet. When compared with the control diet, the diet with 12 % RPS was also found to notably increase acetate, propionate and butyrate contents and up-regulated barrier-related genes including claudin-1, zonula occludens-1, mucin-2 and proglucagon in the caecum. Furthermore, the addition of 12 % RPS significantly reduced plasma TNF-α, IL-1β and endotoxin concentrations. These data revealed that diets supplemented with 12 % RPS partially improved caecal barrier function in meat ducks by enhancing intestinal morphology and barrier markers expression, modulating the microbiota composition and attenuating inflammatory markers.