A critical review on anti-diabetic and anti-obesity effects of dietary resistant starch

Navy Bean Supplementation in Established High-Fat Diet-Induced Obesity Attenuates the Severity of the Obese Inflammatory Phenotype

Cooked common beans (Phaseolus vulgaris) improve intestinal health in lean mice and attenuate intestinal dysbiosis and inflammation when consumed concurrent with obesity development. We determined the effects of a high-fat (HF) bean supplemented diet in mice with established obesity (induced by 12 weeks of HF diet (60% fat as kcal)) compared to obese mice consuming a HF or low-fat (LF) weight loss control diet. Obese C57BL/6 male mice remained consuming HF for eight weeks or were randomly switched from HF to an isocaloric HF with 15.7% cooked navy bean powder diet (HF→HFB) or LF (11% fat as kcal; HF→LF) (n = 12/group). HF→HFB improved the obese phenotype, including (i) fecal microbiome (increased Prevotella, Akkermansia muciniphila, and short-chain fatty acid levels), (ii) intestinal health (increased ZO-1, claudin-2, Muc2, Relmβ, and Reg3γ expression), and (iii) reduced adipose tissue (AT) inflammatory proteins (NFκBp65, STAT3, IL-6, MCP-1, and MIP-1α), versus HF (p < 0.05). Conversely, HF→LF reduced body weight and circulating hormones (leptin, resistin, and PAI-1) versus HF and HF→HFB (p < 0.05); however, AT inflammation and intestinal health markers were not improved to the same degree as HF→HFB (p < 0.05). Despite remaining on a HF obesogenic diet, introducing beans in established obesity improved the obese phenotype (intestinal health and adipose inflammation) more substantially than weight loss alone.

Effects of Banana Resistant Starch on the Biochemical Indexes and Intestinal Flora of Obese Rats Induced by a High-Fat Diet and Their Correlation Analysis

The effects of banana resistant starch (BRS) on obesity-related metabolic and intestinal flora were investigated in a high-fat diet-induced obesity model. After 6 weeks of intervention, the glucolipid metabolism index [blood glucose (GLU), total cholesterol (TC), triacylglycerol (TG), low density lipoprotein-cholesterol (LDL-C), and high density lipoprotein-cholesterol (HDL-C)], hormone index [leptin (LEP), insulin (INS), ghrelin, adiponectin (ADP), and thyroxine (T4)], and 16S rRNA sequencing analyses were performed for each group to explore the regulating effect of intestinal flora and the mechanism of weight loss in obese rats. The results showed that (1) BRS intervention significantly reduced the levels of GLU, TG, TC, LDL-C, LEP, and INS (p < 0.01) and increased the contents of ghrelin (p < 0.05) and ADP (p < 0.01). (2) BRS could improve the diversity of intestinal flora and regulate the overall structure of intestinal microorganisms, mainly by upregulating the Bacteroides/Firmicutes ratio and the relative abundance of Cyanobacteria and downregulating the relative abundances of Deferribacteres and Tenericutes (at the phylum level). BRS could inhibit the proliferation of Turicibacter, Romboutsia, and Oligella and increase the abundances of Bacteroides, Ruminococcaceae, and Lachnospiraceae (at the genus level). (3) Some significant correlations were observed between the gut microbiota and biomarkers. Turicibacter, Romboutsia, and Oligella were positively correlated with GLU, TG, TC, LEP, and INS and negatively correlated with ghrelin and ADP. Bacteroides, Parabacteroides, and Akkermansia were negatively correlated with GLU, TG, and TC. Conclusion: BRS had promising effects on weight loss, which could be associated with the improvement in host metabolism by regulating intestinal flora.

Polysaccharides catabolism by the human gut bacterium -Bacteroides thetaiotaomicron: advances and perspectives

In recent years, the degradation processes of polysaccharides by human gut microbiota are receiving considerable attention due to the discoveries of the powerful function of gut microbiota. Gut microbiota has developed a sensitive, accurate, and complex system for sensing, capturing, and degrading different polysaccharides. Among the gut microbiota, Bacteroides thetaiotaomicron, a representative species of Bacteroides, is considered as the best degrader of polysaccharides and a potential probiotic in pharmaceutical and food industries. Here, we summarize the degradation system of B. thetaiotaomicron and the degradation pathways of different polysaccharides by B. thetaiotaomicron. We also describe a technical route for investigating a specific polysaccharide degradation pathway by human gut bacteria. In addition, we also provide the future perspectives in the development of novel polysaccharides or oligosaccharides drugs, precision microbiology medicine, and personalized nutrition.

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.

Effects of Resistant Starch Supplementation on Glucose Metabolism, Lipid Profile, Lipid Peroxidation Marker, and Oxidative Stress in Overweight and Obese Adults: Randomized, Double-Blind, Crossover Trial

Obesity is a substantial public health challenge across the globe. The use of resistant starch has been proposed as a probable management strategy for complications of obesity. We investigated the effects of resistant starch intake on lipid profiles, glucose metabolism, antioxidant status, lipid peroxidation marker, blood pressure, and anthropometric variables in subjects with overweight or obesity. In this 12-week, randomized, double-blind, placebo-controlled, 2 × 2 crossover trial, 21 Participants (mean age, 35 ± 7.0 years; body mass index, 32.4 ± 3.5 kg/m²) were given 13.5 g Hi-Maize 260 or placebo daily for 4 weeks, separated by a 4-week washout period. Changes in total antioxidant status (p = 0.04) and serum concentrations of insulin in 52.4% participants with insulin levels above 16 µIU/mL at the baseline (p = 0.04) were significantly different in the three phases. In addition, the mean of serum high-density lipoprotein cholesterol after the intervention was significantly higher than after baseline value (p = 0.04). We found no significant differences in serum concentrations of total cholesterol, triacylglycerol, low-density lipoprotein cholesterol, fasting blood sugar, insulin, homeostatic model assessment of insulin resistance, quantitative insulin sensitivity check index, superoxide dismutase activity, malondialdehyde, blood pressure, and anthropometric variables in the three phases of baseline, after intervention with resistant starch and after placebo. Resistant starch consumption improved serum insulin concentrations, lipid profiles, and antioxidant status in subjects with overweight or obesity.

Genetic Modification for Wheat Improvement: From Transgenesis to Genome Editing

To feed the growing human population, global wheat yields should increase to approximately 5 tonnes per ha from the current 3.3 tonnes by 2050. To reach this goal, existing breeding practices must be complemented with new techniques built upon recent gains from wheat genome sequencing, and the accumulated knowledge of genetic determinants underlying the agricultural traits responsible for crop yield and quality. In this review we primarily focus on the tools and techniques available for accessing gene functions which lead to clear phenotypes in wheat. We provide a view of the development of wheat transformation techniques from a historical perspective, and summarize how techniques have been adapted to obtain gain-of-function phenotypes by gene overexpression, loss-of-function phenotypes by expressing antisense RNAs (RNA interference or RNAi), and most recently the manipulation of gene structure and expression using site-specific nucleases, such as CRISPR/Cas9, for genome editing. The review summarizes recent successes in the application of wheat genetic manipulation to increase yield, improve nutritional and health-promoting qualities in wheat, and enhance the crop's resistance to various biotic and abiotic stresses.

Structural Changes of Starch-Lipid Complexes during Postprocessing and Their Effect on In Vitro Enzymatic Digestibility

The effects of cooking and storage on the structure and in vitro enzymatic digestibility of complexes formed between fatty acids and debranched high-amylose starch (DHA7-FA) were investigated for the first time. Cooking greatly decreased the crystallinities of DHA7-lauric acid (LA) and DHA7-myristic acid (MA) complexes but had little effect on the crystallinities of DHA7-palmitic acid (PA) and DHA7-stearic acid (SA) complexes. Cooking increased the enthalpy-change (Δ H) values and short-range molecular orders of DHA7-FA complexes. Cooking decreased the in vitro enzymatic digestibility of DHA7-FA complexes, with the extent of the effect decreasing with increasing fatty acid chain length. Holding the samples at 4 °C for 24 h after cooking did not greatly affect the long- and short-range molecular orders nor the in vitro enzymatic digestibility of DHA7-FA complexes. From this study, we conclude that cooking disrupted the long-range crystalline structures of DHA7-LA and DHA7-MA complexes but enhanced the short-range molecular orders of all of the DHA7-FA complexes. The latter effect accounted mainly for the reduced in vitro enzymatic digestibility of DHA7-FA complexes.

The beneficial effects of purple yam (Dioscorea alata L.) resistant starch on hyperlipidemia in high-fat-fed hamsters

In this study, we investigated the interventional effect of resistant starch (RS) obtained from purple yam (Dioscorea alata L.) on regulating lipid metabolism and gut microbiota in hyperlipidemic hamsters.