Greater satiety response with resistant starch and corn bran in human subjects

Almond supplementation on appetite measures, body weight, and body composition in adults: A systematic review and dose-response meta-analysis of 37 randomized controlled trials

BACKGROUND AND OBJECTIVE

Almond consumption has an inverse relationship with obesity and factors related to metabolic syndrome. However, the results of available clinical trials are inconsistent. Therefore, we analyzed the results of 37 randomized controlled trials (RCTs) and evaluated the association of almond consumption with subjective appetite scores and body compositions.

METHODS

Net changes in bodyweight, body mass index (BMI), waist circumference (WC), fat mass (FM), body fat percent, fat-free mass (FFM), waist-to-hip ratio (WHR), visceral adipose tissue (VAT), and subjective appetite scores were used to calculate the effect size, which was reported as a weighted mean differences (WMD) and 95% confidence interval (CI).

RESULTS

This meta-analysis was performed on 37 RCTs with 43 treatment arms. The certainty in the evidence was very low for appetite indices, body fat percent, FFM, VAT, and WHR, and moderate for other parameters as assessed by the GRADE evidence profiles. Pooled effect sizes indicated a significant reducing effect of almond consumption on body weight (WMD: -0.45 kg, 95% CI: -0.85, -0.05, p = 0.026), WC (WMD: -0.66 cm, 95% CI: -1.27, -0.04, p = 0.037), FM (WMD: -0.66 kg, 95% CI: -1.16, -0.17, p = 0.009), and hunger score (WMD: -1.15 mm, 95% CI: -1.98, -0.32, p = 0.006) compared with the control group. However, almond did not have a significant effect on BMI (WMD: -0.20 kg m-2, 95% CI: -0.46, 0.05, p = 0.122), body fat percent (WMD: -0.39%, 95% CI: -0.93, 0.14, p = 0.154), FFM (WMD: -0.06, 95% CI: -0.47, 0.34, p = 0.748), WHR (WMD: -0.04, 95% CI: -0.12, 0.02, p = 0.203), VAT (WMD: -0.33 cm, 95% CI: -0.99, 0.32), fullness (WMD: 0.46 mm, 95% CI: -0.95, 1.88), desire to eat (WMD: 0.98 mm, 95% CI: -4.13, 2.23), and prospective food consumption (WMD: 1.08 mm, 95% CI: -2.11, 4.28). Subgroup analyses indicated that consumption of ≥50 g almonds per day resulted in a significant and more favorable improvement in bodyweight, WC, FM, and hunger score. Body weight, WC, FM, body fat percent, and hunger scores were decreased significantly in the trials that lasted for ≥12 weeks and in the subjects with a BMI < 30 kg/m2. Furthermore, a significant reduction in body weight and WC was observed in those trials that used a nut-free diet as a control group, but not in those using snacks and other nuts. The results of our analysis suggest that almond consumption may significantly improve body composition indices and hunger scores when consumed at a dose of ≥50 g/day for ≥12 weeks by individuals with a BMI < 30 kg/m2.

CONCLUSION

However, further well-constructed randomized clinical trials are needed in order ascertain the outcome of our analysis.

Ultraprocessed Foods and Obesity Risk: A Critical Review of Reported Mechanisms

Epidemiologic evidence supports a positive association between ultraprocessed food (UPF) consumption and body mass index. This has led to recommendations to avoid UPFs despite very limited evidence establishing causality. Many mechanisms have been proposed, and this review critically aimed to evaluate selected possibilities for specificity, clarity, and consistency related to food choice (i.e., low cost, shelf-life, food packaging, hyperpalatability, and stimulation of hunger/suppression of fullness); food composition (i.e., macronutrients, food texture, added sugar, fat and salt, energy density, low-calorie sweeteners, and additives); and digestive processes (i.e., oral processing/eating rate, gastric emptying time, gastrointestinal transit time, and microbiome). For some purported mechanisms (e.g., fiber content, texture, gastric emptying, and intestinal transit time), data directly contrasting the effects of UPF and non-UPF intake on the indices of appetite, food intake, and adiposity are available and do not support a unique contribution of UPFs. In other instances, data are not available (e.g., microbiome and food additives) or are insufficient (e.g., packaging, food cost, shelf-life, macronutrient intake, and appetite stimulation) to judge the benefits versus the risks of UPF avoidance. There are yet other evoked mechanisms in which the preponderance of evidence indicates ingredients in UPFs actually moderate body weight (e.g., low-calorie sweetener use for weight management; beverage consumption as it dilutes energy density; and higher fat content because it reduces glycemic responses). Because avoidance of UPFs holds potential adverse effects (e.g., reduced diet quality, increased risk of food poisoning, and food wastage), it is imprudent to make recommendations regarding their role in diets before causality and plausible mechanisms have been verified.

Sustainable Strategies for Increasing Legume Consumption: Culinary and Educational Approaches

Legumes are nutrient-dense crops with health-promoting benefits. However, several barriers are associated with their consumption. Emerging issues including food neophobic tendencies or taboos, unclear dietary guidelines on legume consumption, health concerns, and socio-economic reasons, as well as long cooking procedures, adversely affect legume consumption frequency. Pre-treatment methods, including soaking, sprouting, and pulse electric field technology, are effective in reducing the alpha-oligosaccharides and other anti-nutritional factors, eventually lowering cooking time for legumes. Extrusion technology used for innovative development of legume-enriched products, including snacks, breakfast cereals and puffs, baking and pasta, represents a strategic way to promote legume consumption. Culinary skills such as legume salads, legume sprouts, stews, soups, hummus, and the development of homemade cake recipes using legume flour could represent effective ways to promote legume consumption. This review aims to highlight the nutritional and health effects associated with legume consumption, and strategies to improve their digestibility and nutritional profile. Additionally, proper educational and culinary approaches aimed to improve legumes intake are discussed.

The Effect of Buckwheat Resistant Starch on Intestinal Physiological Function

Resistant starch appears to have promising effects on hypertension, cardiovascular and enteric illness. The influence of resistant starch on intestinal physiological function has drawn great attention. In this study, we first analyzed the physicochemical characteristics, including the crystalline properties, amylose content, and anti-digestibility among different types of buckwheat-resistant starch. The influence of resistant starch on the physiological functions of the mouse intestinal system, contained defecation, and intestinal microbes were also evaluated. The results showed that the crystalline mold of buckwheat-resistant starch changed from A to B + V after acid hydrolysis treatment (AHT) and autoclaving enzymatic debranching treatment (AEDT). The amylose content in AEDT was higher than in AHT and raw buckwheat. Moreover, the anti-digestibility of AEDT was also stronger than that in AHT and raw buckwheat. The buckwheat-resistant starch can promote bowel intestinal tract movement. The quantity of intestinal microbe was regulated by buckwheat-resistant starch. Our research demonstrates an effective preparation method for improving the quality of buckwheat-resistant starch and found that buckwheat-resistant starch has the role of adjusting the distribution of the intestinal flora and maintaining the health of the body.

Starch intake, amylase gene copy number variation, plasma proteins, and risk of cardiovascular disease and mortality

BACKGROUND

Salivary amylase, encoded by the AMY1 gene, initiate the digestion of starch. Whether starch intake or AMY1 copy number is related to disease risk is currently rather unknown. The aim was to investigate the association between starch intake and AMY1 copy number and risk of cardiovascular disease (CVD) and mortality and whether there is an interaction. In addition, we aim to identify CVD-related plasma proteins associated with starch intake and AMY1 copy number.

METHODS

This prospective cohort study used data from 21,268 participants from the Malmö Diet and Cancer Study. Dietary data were collected through a modified diet history method and incident CVD and mortality were ascertained through registers. AMY1 gene copy number was determined by droplet digital polymerase chain reaction, a risk score of 10 genetic variants in AMY1 was measured, and a total of 88 selected CVD-related proteins were measured. Cox proportional hazards regression was used to analyze the associations of starch intake and AMY1 copy number with disease risk. Linear regression was used to identify plasma proteins associated with starch intake and AMY1 copy number.

RESULTS

Over a median of 23 years' follow-up, 4443 individuals developed CVD event and 8125 died. After adjusting for potential confounders, a U-shape association between starch intake and risk of CVD (P-nonlinearity = 0.001) and all-cause mortality (P-nonlinearity = 0.03) was observed. No significant association was found between AMY1 copy number and risk of CVD and mortality, and there were no interactions between starch intake and AMY1 copy number (P interaction > 0.23). Among the 88 plasma proteins, adrenomedullin, interleukin-1 receptor antagonist protein, fatty acid-binding protein, leptin, and C-C motif chemokine 20 were associated with starch intake after adjusting for multiple testing.

CONCLUSIONS

In this large prospective study among Swedish adults, a U-shaped association between starch intake and risk of CVD and all-cause mortality was found. Several plasma proteins were identified which might provide information on potential pathways for such association. AMY1 copy number was not associated with CVD risk or any of the plasma proteins, and there was no interaction between starch intake and AMY1 copy number on disease risk.

Acute postprandial gut hormone, leptin, glucose and insulin responses to resistant starch in obese children: a single blind crossover study

INTRODUCTION

Resistant starch (RS) has beneficial effects on postprandial glucose metabolism in both animals and adults. Hitherto, there have been no studies in children of the acute metabolic and hormonal effects of RS-containing meals.

OBJECTIVES

We aimed to compare serial plasma glucose, insulin, gut hormone, leptin profiles and satiety scores in obese children after meals containing variable amounts of RS.

METHODS

This was a single blind, non-randomised, crossover study of 20 obese children aged 10-14 years old without comorbidities. Three test meals containing rice (M1), rice cooked with coconut oil (M2), rice cooked in coconut oil with lentils (M3) were given in sequence after a 12-hour fast . Blood samples were analysed for glucose (PG), insulin, leptin, glucagon-like polypeptide (GLP) 1, ghrelin and peptide YY (PYY) at appropriate times between 0 and 180 min.

RESULTS

Meal M2 resulted in significantly lower postprandial glucose values compared with meal M1 (maximal incremental glucose, ∆C_max, p<0.05; area under the curve, ∆AUC_0-3, p<0.01) and meal M3 (maximal concentration, C_max, p<0.01; ∆C_max, p<0.001, and ∆AUC_0-3p<0.01). M2 also produced lower insulin values compared with M1 (p<0.05). Postprandial ghrelin was significantly higher after M1 compared with M3 (p<0.05). PYY, GLP1 and median satiety scores were not significantly different between the three meals.

CONCLUSION

This study shows that M2, the meal containing RS alone, induced beneficial effects on acute postprandial glucose, insulin and ghrelin concentrations in obese children without diabetes. Acute postprandial satiety scores were not significantly affected by the three meals.

TRIAL REGISTRATION NUMBER

SLCTR/2020/007.

Resistant starch wheat increases PYY and decreases GIP but has no effect on self-reported perceptions of satiety

Dietary fiber has numerous health benefits, such as increasing satiety, and is regularly included in healthy dietary recommendations. However, different types and sources of fiber vary in their chemical properties and biological effects. This double-blind, randomized, placebo-controlled, crossover study investigated the effects of resistant starch type 2 (RS2) from wheat on self-reported perceptions of satiety and associated gut hormones in 30 healthy adults ages 40-65 years of age. Participants consumed rolls made using either RS2-enriched wheat flour or a wild-type flour for one week before a test day during which they ate a mixed meal containing the same roll type. Both self-reported perceptions of satiety and plasma concentrations of gut hormones were measured following the meal to assess whether the RS2-enriched wheat enhanced satiety and suppressed hunger for a longer period than the control wheat. Exploratory analysis indicated that fasting and peak concentration of peptide YY_3-36 (PYY_3-36; q_fast = 0.02, q_peak = 0.02) increased, while peak concentration and iAUC of glucose-dependent insulinotropic peptide (GIP; q_peak < 0.001, q_iAUC < 0.001) decreased after ingesting RS2-enriched wheat. However, self-reported perceptions of hunger or fullness using visual analog scales (VAS) did not differ following the test meal.

The impact of starchy food structure on postprandial glycemic response and appetite: a systematic review with meta-analysis of randomized crossover trials

BACKGROUND

Starchy foods can have a profound effect on metabolism. The structural properties of starchy foods can affect their digestibility and postprandial metabolic responses, which in the long term may be associated with the risk of type 2 diabetes and obesity.

OBJECTIVES

This systematic review sought to evaluate the clinical evidence regarding the impact of the microstructures within starchy foods on postprandial glucose and insulin responses alongside appetite regulation.

METHODS

A systematic search was performed in the PUBMED, Ovid Medicine, EMBASE, and Google Scholar databases for data published up to 18 January 2021. Data were extracted by 3 independent reviewers from randomized crossover trials (RCTs) that investigated the effect of microstructural factors on postprandial glucose, insulin, appetite-regulating hormone responses, and subjective satiety scores in healthy participants.

RESULTS

We identified 745 potential articles, and 25 RCTs (n = 369 participants) met our inclusion criteria: 6 evaluated the amylose-to-amylopectin ratio, 6 evaluated the degree of starch gelatinization, 2 evaluated the degree of starch retrogradation, 1 studied starch-protein interactions, and 12 investigated cell and tissue structures. Meta-analyses showed that significant reductions in postprandial glucose and insulin levels was caused by starch with a high amylose content [standardized mean difference (SMD) = -0.64 mmol/L*min (95% CI: -0.83 to -0.46) and SMD = -0.81 pmol/L*min (95% CI: -1.07 to -0.55), respectively], less-gelatinized starch [SMD = -0.54 mmol/L*min (95% CI: -0.75 to -0.34) and SMD = -0.48 pmol/L*min (95% CI: -0.75 to -0.21), respectively], retrograded starch (for glucose incremental AUC; SMD = -0.46 pmol/L*min; 95% CI: -0.80 to -0.12), and intact and large particles [SMD = -0.43 mmol/L*min (95% CI: -0.58 to -0.28) and SMD = -0.63 pmol/L*min (95% CI: -0.86 to -0.40), respectively]. All analyses showed minor or moderate heterogeneity (I2 < 50%). Sufficient evidence was not found to suggest how these structural factors influence appetite.

CONCLUSIONS

The manipulation of microstructures in starchy food may be an effective way to improve postprandial glycemia and insulinemia in the healthy population. The protocol for this systematic review and meta-analysis was registered in the international prospective register of systematic reviews (PROSPERO) as CRD42020190873.

Effect of biscuits formulated with high-amylose maize flour on satiety-related sensations and food intake

The amount of amylose within a food may elicit lower glycemic and insulin postprandial responses and thus potentially modulate the satiating effect. In this context, the effect of biscuits formulated with high amylose starch (HAS) flour on satiety-related sensations and food intake was studied. Three types of biscuits were produced: control biscuit (CRT, 0% of HAS), Amy-25 (25% HAS), and Amy-50 (50% HAS). Fifteen healthy volunteers were enrolled to conduct two in vivo experiments. In experiment 1, volunteers consumed biscuits ad libitum and their sensations of satiety and food intake were evaluated. In experiment 2, volunteers received a quantity of biscuits equivalent to the 20% of the daily estimated energy requirements, and both satiety-related sensations and food intake were checked at subsequent meal. The Amy-50 significantly reduced food intake at subsequent meal (p ˂ 0.05), compared to Amy-25 and CRT. The satiety-related sensations were not significantly affected in both experiments, excepted for intra-meal hunger variation induced by Amy-25 which resulted significantly higher (p ˂ 0.05) than Amy-50 and CRT. These findings support the need to reformulate carbohydrate rich foods commonly consumed in a dietary context, to provide consumers healthier alternatives to prevent and tackle obesity and related chronic diseases.

Triple null mutations in starch synthase SSIIa gene homoeologs lead to high amylose and resistant starch in hexaploid wheat

BACKGROUND

Lack of nutritionally appropriate foods is one of the leading causes of obesity in the US and worldwide. Wheat (Triticum aestivum) provides 20% of the calories consumed daily across the globe. The nutrients in the wheat grain come primarily from the starch composed of amylose and amylopectin. Resistant starch content, which is known to have significant human health benefits, can be increased by modifying starch synthesis pathways. Starch synthase enzyme SSIIa, also known as starch granule protein isoform-1 (SGP-1), is integral to the biosynthesis of the branched and readily digestible glucose polymer amylopectin. The goal of this work was to develop a triple null mutant genotype for SSIIa locus in the elite hard red winter wheat variety 'Jagger' and evaluate the effect of the knock-out mutations on resistant starch content in grains with respect to wild type.

RESULTS

Knock-out mutations in SSIIa in the three genomes of wheat variety 'Jagger' were identified using TILLING. Subsequently, these loss-of function mutations on A, B, and D genomes were combined by crossing to generate a triple knockout mutant genotype Jag-ssiia-∆ABD. The Jag-ssiia-∆ABD had an amylose content of 35.70% compared to 31.15% in Jagger, leading to ~ 118% increase in resistant starch in the Jag-ssiia-∆ABD genotype of Jagger wheat. The single individual genome mutations also had various effects on starch composition.

CONCLUSIONS

Our full null Jag-ssiia-∆ABD mutant showed a significant increase in RS without the shriveled grain phenotype seen in other ssiia knockouts in elite wheat cultivars. Moreover, this study shows the potential for developing nutritionally improved foods in a non-GM approach. Since all the mutants have been developed in an elite wheat cultivar, their adoption in production and supply will be feasible in future.

The effect of acute consumption of resistant starch on appetite in healthy adults; a systematic review and meta-analysis of the controlled clinical trials

BACKGROUND & AIMS

Although several clinical trials have assessed the effect of Resistant Starch (RS) supplementation on appetite, the results have been inconsistent. Therefore, this study aimed to assess the effect of RS on the healthy adults' rating of appetite.

MATERIALS AND METHODS

To this end, Pubmed, CENTRAL, Web of science, Scopus, Medline, and Proquest were systematically searched to find the relevant randomized, and placebo-controlled human trials up to June 2019. As a result, the area under curve (AUC) and standard deviations of the participants' rating appetite were extracted from four eligible studies.

RESULTS

Meta-analysis showed a lower appetite in RS group compared to the controls (weighted mean difference [WMD] = -1.375 mm min, 95% confidence interval [95%CI]: -1.673, -1.076). Since high heterogeneity was observed among the included studies (I² = 94.5%, P < 0.001), subgroup analysis was carried out by RS dose, RS type, duration of supplementation, and time of AUC measuring. In studies that used RS dose of ≥25 gr, heterogeneity disappeared (P = 0.560, I² = 0%). In such studies, a significant reduction was observed in rating of appetite (WMD = -4.513 mm min, 95%CI: -5.270, -3.755; P < 0.001) than studies with RS dose of <25 gr (WMD = -0.799 mm min, 95%CI: -1.123,-0.474; P < 0.001). Additionally, subgroup analysis based on the type of RS showed a significant decrease of appetite in studies that used RS2 (WMD = -4.808 mm min, 95%CI: -5.834, -3.782; P < 0.001) than RS1 (WMD = -0.128 mm min, 95%CI: -0.457, 0.202; P = 0.448).

CONCLUSIONS

To decrease the rate of appetite more effectively, we suggest other researchers to identify RS dose and type.

The Effect of Soluble Fiber Dextrin on Subjective and Physiological Markers of Appetite: A Randomized Trial

Obesity is a leading public health problem throughout the world. The development of foods that increase satiety and reduce food may aid weight management. This study determined the effect of consuming soluble fiber dextrin (SFD) on appetite, appetitive hormones, breath hydrogen and food intake in adults. Forty-three participants completed this study. For each treatment, 50% of the SFD was provided in liquid form as part of breakfast and 50% in solid form as a morning snack. Appetite questionnaires, blood and breath samples were collected immediately before breakfast and at regular intervals during the test session. The participants consumed an ad libitum lunch meal, afternoon snack and dinner meal, and the amount eaten was recorded. Following dinner, participants left the laboratory but were required to keep a diet diary for the remainder of the day. Breath hydrogen concentration was significantly higher following the consumption of SFD compared to control (p < 0.05). There was no observed overall treatment effect of consuming SFD on GLP-1 (Glucagon-Like-Peptide-1), ghrelin, CCK-8 (Cholecystokinin) or PYY_3-36 (Petptide YY) (p > 0.05). Moreover, consuming foods containing SFD had no effect on subjective appetite or food intake (p > 0.05). Consuming foods containing SFD increased breath hydrogen but did not influence food intake, appetite or appetitive hormones. However, the limitations of this study may have individually or collectively masked an effect of SFD on food intake and appetite.

Effect of semolina pudding prepared from starch branching enzyme IIa and b mutant wheat on glycaemic response in vitro and in vivo: a randomised controlled pilot study

Refined starchy foods are usually rapidly digested, leading to poor glycaemic control, but not all starchy foods are the same. Complex carbohydrates like resistant starch (RS) have been shown to reduce the metabolic risk factors for chronic diseases such as hyperglycaemia and overweight. The aim of the project was to develop a semolina-based food made from a starch branching enzyme II (sbeIIa/b-AB) durum wheat mutant with a high RS content and to measure its glycaemic index using a double-blind randomised pilot study. We report here the amylose, RS and non-starch polysaccharide concentration of raw sbeIIa/b-AB and wild-type control (WT) semolina. We measured RS after cooking to identify a model food for in vivo testing. Retrograded sbeIIa/b-AB semolina showed a higher RS concentration than the WT control (RS = 4.87 ± 0.6 g per 100 g, 0.77 ± 0.34 g per 100 g starch DWB, respectively), so pudding was selected as the test food. Ten healthy participants consumed ∼50 g of total starch from WT and sbeIIa/b-AB pudding and a standard glucose drink. Capillary blood glucose concentrations were measured in the fasting and postprandial state (2 h): incremental area-under-the-curve (iAUC) and GI were calculated. We found no evidence of difference in GI between sbeIIa/b-AB pudding and the WT control, but the starch digestibility was significantly lower in sbeIIa/b-AB pudding compared to the WT control in vitro (C90 = 33.29% and 47.38%, respectively). Based on these results, novel sbeIIa/b-AB wheat foods will be used in future in vivo studies to test the effect of different RS concentrations and different food matrices on glycaemia.

Resistant Starch Content in Foods Commonly Consumed in the United States: A Narrative Review

Resistant starch (RS; types 1 to 5) cannot be digested in the small intestine and thus enters the colon intact, with some types capable of being fermented by gut microbes. As a fiber, types 1, 2, 3, and 5 are found naturally in foods, while types 2, 3, and 4 can be added to foods as a functional ingredient. This narrative review identifies RS content in whole foods commonly consumed in the United States. Scientific databases (n=3) were searched by two independent researchers. Ninety-four peer-reviewed articles published between 1982 and September 2018 were selected in which the RS was quantified and the food preparation method before analysis was suitable for consumption. The RS from each food item was adjusted for moisture if the RS value was provided as percent dry weight. Each food item was entered into a database according to food category, where the weighted mean±weighted standard deviation was calculated. The range of RS values and overall sample size for each food category were identified. Breads, breakfast cereals, snack foods, bananas and plantains, grains, pasta, rice, legumes, and potatoes contain RS. Foods that have been cooked then chilled have higher RS than cooked foods. Foods with higher amylose concentrations have higher RS than native varieties. The data from this database will serve as a resource for health practitioners to educate and support patients and clients interested in increasing their intake of RS-rich foods and for researchers to formulate dietary interventions with RS foods and examine associated health outcomes.

Identifying genes for resistant starch, slowly digestible starch, and rapidly digestible starch in rice using genome-wide association studies

BACKGROUND

The digestibility of starch is important for the nutritive value of staple food. Although several genes are responsible for resistant starch (RS) and slowly digestible starch (SDS), gaps persist concerning the molecular basis of RS and SDS formation due to the complex genetic mechanisms of starch digestibility.

OBJECTIVES

The objective of this study was to identify new genes for starch digestibility in rice and interprete the genetic mechanisms of RS and SDS by GWAS.

METHODS

Genome-wide association studies were conducted by associating the RS and SDS phenotypes of 104 re-sequenced rice lines to an SNP dataset of 2,288,867 sites using a compressed mixed linear model. Candidate genes were identified according to the position of the SNPs based on data from the MSU Rice Genome Annotation Project.

RESULTS

Seven quantitative trait loci (QTLs) were detected to be associated with the RS content, among which the SNP 6 m1765761 was located on Waxy. Starch branching enzymes IIa (BEIIa) close to QTL qRS-I4 was detected and further identified as a specific candidate gene for RS in INDICA. Two QTLs were associated with SDS, and the LOC_Os09g09360 encoding lipase was identified as a causal gene for SDS.

CONCLUSIONS

GWAS is a valid strategy to genetically dissect the formation of starch digestion properties in rice. RS formation in grains is dependent on the rice type; lipid might also contribute to starch digestibility and should be an alternative factor to improve rice starch digestibility.

Effects of edible plant polyphenols on gluten protein functionality and potential applications of polyphenol-gluten interactions

Expanding plant-based protein applications is increasingly popular. Polyphenol interactions with wheat gluten proteins can be exploited to create novel functional foods and food ingredients. Polyphenols are antioxidants, thus generally decrease gluten strength by reducing disulfide cross-linking. Monomeric polyphenols can be used to reduce dough mix time and improve flexibility of the gluten network, including to plasticize gluten films. However, high-molecular-weight polyphenols (tannins) cross-link gluten proteins, thereby increasing protein network density and strength. Tannin-gluten interactions can greatly increase gluten tensile strength in dough matrices, as well as batter viscosity and stability. This could be leveraged to reduce detrimental effects of healthful inclusions, like bran and fiber, to loaf breads and other wheat-based products. Further, the dual functions of tannins as an antioxidant and gluten cross-linker could help restructure gluten proteins and improve the texture of plant-based meat alternatives. Tannin-gluten interactions may also be used to reduce inflammatory effects of gluten experienced by those with gluten allergies and celiac disease. Other potential applications of tannin-gluten interactions include formation of food matrices to reduce starch digestibility; creation of novel biomaterials for edible films or medical second skin type bandages; or targeted distribution of micronutrients in the digestive tract. This review focuses on the effects of polyphenols on wheat gluten functionality and discusses emerging opportunities to employ polyphenol-gluten interactions.

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.

Postprandial Glycemia, Insulinemia, and Antioxidant Status in Healthy Subjects after Ingestion of Bread made from Anthocyanin-Rich Riceberry Rice

Riceberry rice, a gluten-free grain, contains many nutrient components, including carbohydrates, proteins, certain fatty acids, and micronutrients, as well as bioactive non-nutrient compounds, such as polyphenolic compounds. This study aimed to evaluate the effect of bread made from anthocyanin-rich Riceberry rice on the postprandial glycemic response, glucagon-like peptide-1 (GLP-1), antioxidant status, and subjective ratings of appetite. In the crossover design, 16 healthy participants (six men and 10 women) completed four sessions involving blood collection in the fasting state and at 30, 60, 90, 120, 150, and 180 min after food consumption (50 g of available carbohydrate) in a randomized order: 1) glucose solution, 2) wheat bread (WB), 3) Riceberry rice bread (RRB), and 4) Hom Mali bread (HMB). Consumption of RRB resulted in significantly lower postprandial plasma glucose concentration at 30 and 60 min when compared to HMB. No difference in postprandial glucose concentration between RRB and WB was observed. In addition, postprandial plasma insulin showed a significant decrease in the group which received RRB at 15 and 60 min, as compared to HMB. In comparison with 50 g of glucose, as a reference, the glycemic index (GI) of RRB, WB, and HMB was 69.3 ± 4.4, 77.8 ± 4.6, and 130.6 ± 7.9, respectively. Interestingly, the ferric-reducing ability of plasma (FRAP) level was shown to significantly increase after consumption of RRB. In the meantime, a significant decrease in the postprandial FRAP level was also observed following an intake of WB and HMB. All breads caused increases in the postprandial plasma protein thiol group and had similar effects on hunger, fullness, desire to eat, and satiety ratings. However, consumption of RBB, WB, and HMB did not change plasma GLP-1 and malondialdehyde (MDA) levels when compared to the baseline. The findings suggest that anthocyanin-rich Riceberry rice can be a natural ingredient for gluten-free bread which reduced glycemic response together with improvement of antioxidant status in healthy subjects.

Whole grain and high-fibre grain foods: How do knowledge, perceptions and attitudes affect food choice?

The health benefits of whole grains and dietary fibre are well established, however intakes of both remain low across the globe. Innovative added-fibre refined grain products may present a solution to increase fibre intakes given potential sensory barriers to whole grain intake. However, to consider the efficacy of such products, or potential alternative measures, an awareness of consumer knowledge, perceptions and attitudes towards both whole grain and added-fibre grain foods is needed. Focus groups (with adults with no formal nutrition education) were conducted to explore factors affecting consumer grain choice. Discussions were transcribed verbatim and analysed using inductive thematic analysis. Nine focus groups composed of 52 participants (23 men; 29 women) were conducted. Participants tended to report choosing 'grainy' bread but few other whole grain foods. Most participants were unaware of the long-term health benefits of whole grains, recommended whole grain intakes, or how to identify foods that were high in whole grains, thereby limiting motivation to increase intake. Additionally, scepticism surrounding the health value of carbohydrate-based foods appeared to hinder grain intakes in general. These findings suggest that further public education and promotion of whole grain benefits, with a focus on food-based targets and messaging, may be important in efforts to increase whole grain and subsequently fibre intakes. Added-fibre grain products may be a useful addition, specifically for avid whole grain-avoiders who are unlikely to accept whole grain sensory properties. However, as most participants were open to whole grain consumption, industry innovation should also focus efforts on increasing availability and variety of products high in whole grains.

Fruits

Fruits come in a wide variety of colors, shapes, and flavors. This chapter will cover selected fruits that are known to be healthy and highly nutritious. These fruits were chosen due to their common usage and availability. Since it is not possible to cover all health benefits or essential nutrients and important phytochemicals of the fruit composition, this chapter will focus on the key valuable constituents and their potential health effects.

Low intake of digestible carbohydrates ameliorates duodenal absorption of carbohydrates in mice with glucose metabolism disorders induced by artificial sweeteners

BACKGROUND

Long-term artificial sweetener consumption has been reported to induce glucose intolerance, and the intestinal microbiota seems as an important target. While the impacts of artificial sweeteners on energy balance remain controversial, this work aimed to evaluate the protective effects in mice of a low digestible carbohydrate (LDC) diet on plasma glucose, plasma fasting insulin, sweet taste receptors, glucose transporters, and absorption of carbohydrates, together with consumption of acesulfame potassium (AK) or saccharin (SAC).

RESULTS

Artificial sweetener was administered to mice for 12 weeks to induce glucose metabolism disorders; mice were treated with an LDC diet for the final 6 weeks. The experimental groups were treated with an LDC diet that had the same energy as the normal-diet group. Prolonged administration of artificial sweeteners led to metabolic dysfunction, characterized by significantly increased plasma glucose, insulin resistance, sweet taste receptors, glucose transporters, and absorption of carbohydrates. Treatment with an LDC diet positively modulated these altered parameters, suggesting overall beneficial effects of an LDC diet on detrimental changes associated with artificial sweeteners.

CONCLUSIONS

Reducing digestible carbohydrates in the diet can significantly reduce the absorption of carbohydrates and improve glucose metabolism disorders caused by dietary factors. These effects may be due to the fact that reducing the amount of digestible carbohydrates in the feed can reduce the number of intestinal sweet receptors induced by exposure to artificial sweeteners. © 2019 Society of Chemical Industry.

GWAS for Starch-Related Parameters in Japonica Rice (Oryza sativa L.)

Rice quality is mainly related to the following two starch components, apparent amylose content (AAC) and resistant starch (RS). The former affects grain cooking properties, while RS acts as a prebiotic. In the present study, a Genome Wide Association Scan (GWAS) was performed using 115 rice japonica accessions, including tropical and temperate genotypes, with the purpose of expanding the knowledge of the genetic bases affecting RS and AAC. High phenotypic variation was recorded for the two traits, which positively correlated. Moreover, both the parameters correlated with seed length (positive correlation) and seed width (negative correlation). A correlational selection according to human preferences has been hypothesized for the two starch traits and grain size. In addition, human selection has been proposed as the causal agent even for the different phenotypes related to starch and grain size showed by the tropical and temperate japonica accessions utilized in this study. The present GWAS led to the identification of 11 associations for RS on seven chromosomes and five associations for AAC on chromosome 6. Candidate genes and co-positional relationships with quantitative trait loci (QTLs) previously identified as affecting RS and AAC were identified for 6 associations. The candidate genes and the new RS- and/or AAC-associated regions detected provide valuable sources for future functional characterizations and for breeding programs aimed at improving rice grain quality.

High-Amylose Wheat Lowers the Postprandial Glycemic Response to Bread in Healthy Adults: A Randomized Controlled Crossover Trial

BACKGROUND

Conventional wheat-based foods contain high concentrations of readily digestible starch that commonly give these foods a high postprandial glycemic response and may contribute to the development of type 2 diabetes and cardiovascular disease.

OBJECTIVES

The aim of this study was to determine if bread made from high-amylose wheat (HAW) and enriched in resistant starch dampens postprandial glycemia compared with bread made from conventional low-amylose wheat (LAW).

METHODS

This single-center, randomized, double-blinded, crossover controlled study involved 7 consecutive weekly visits. On separate mornings, 20 healthy nondiabetic men and women (mean age 30 ± 3 y; body mass index 23 ± 0.7 kg/m2) consumed a glucose beverage or 4 different breads (each 121 g); LAW-R (refined), LAW-W (wholemeal), HAW-R, or HAW-W. The starch contents of the LAW and HAW breads were 24% and 74% amylose, respectively. Venous blood samples were collected at regular intervals before and for 3 h after the breakfast meal to measure plasma glucose, insulin, ghrelin, and incretin hormone concentrations, and the incremental area under the curve (AUC) was calculated (mmol/L × 3 h). Satiety and cravings were also measured at 30-min intervals during the postprandial period.

RESULTS

HAW breads had a glycemic response (AUC) that was 39% less than that achieved with conventional wheat breads (HAW 39 ± 5 mmol/L × 3 h; LAW 64 ± 5 mmol/L × 3 h; P < 0.0001). Insulinemic and incretin responses were 24-30% less for HAW breads than for LAW breads (P < 0.05). Processing of the flour (wholemeal or refined) did not affect the glycemic, insulinemic, or incretin response. The HAW breads did not influence plasma ghrelin, or subjective measures of satiety or cravings during the postprandial period.

CONCLUSIONS

Replacing LAW with HAW flour may be an effective strategy for lowering postprandial glycemic and insulinemic responses to bread in healthy men and women, but further research is warranted. This trial was registered at the Australian and New Zealand Clinical Trials Registry as ACTRN12616001289404.

Pigs Ferment Enzymatically Digestible Starch when it Is Substituted for Resistant Starch

BACKGROUND

Feeding behavior is controlled by satiety mechanisms, which are affected by the extent of starch digestion, and thus resistant starch (RS) intake. Alterations in feeding behavior to changes in RS intake may depend on the adaptation of processes involved when shifting from starch digestion to fermentation or vice versa.

OBJECTIVES

The aim of this study was to investigate how growing pigs adapt their feeding behavior in response to increasing and decreasing dietary RS concentrations.

METHODS

Thirty-six groups of 6 pigs (25.4 ± 2.8 kg; Hypor Libra × Hypor Maxter; male:female, 1:1) were fed diets containing 50% high-amylose maize starch (high RS; HRS) or waxy maize starch (low RS; LRS). Over 28 d, diets were exchanged following a 5-step titration (25% per step) that was executed in the upward (LH) or downward direction (HL). Twelve groups received a control diet to correct for changes over time. Individual feeding behavior and total tract starch digestion and fermentation were evaluated. The response in each parameter to increasing dietary HRS inclusion was estimated through the use of linear regression procedures, and tested for titration direction and sex effects.

RESULTS

Complete substitution of LRS with HRS increased the proportion of starch fermented, which was greater in LH pigs than in HL pigs (17.6% compared with 8.18%; P < 0.001), and decreased the feed intake (106 g/d; P = 0.021) and meal size (12.6 g; P < 0.001) of LH pigs, but not of HL pigs. In LH pigs, the size of the starch fermentation response positively correlated with the size of the feed intake response (r = 0.90, P < 0.001).

CONCLUSIONS

The attenuated response in starch fermentation in HL pigs indicates that pigs adapt more slowly to dietary supply of digestible starch than to RS, consequently resulting in fermentation of enzymatically digestible starch. Feed intake and feeding behavior only changed in pigs poorly adapting to RS, indicating that adequacy of adaptation, rather than RS itself, drives feed intake. These findings stress the importance of diet history for nutrient digestion and feeding behavior.

Starch digestion kinetics of extruded reformed rice is changed in different ways with added protein or fiber

White rice is considered a high glycemic index (GI) food and extruded reformed rice offers the opportunity to design a lower GI product. This study tested the effect of added soy protein isolate (SPI) or dietary fibers [corn bran (CB), resistant maltodextrin (RMD)] to delay in vitro digestion, and on human gastric emptying rate and satiety scoring. Starch digestion using a human simulated system showed a single-phase kinetic pattern for regular reformed rice and two-phase kinetic patterns for 20% supplemented extruded rice, which lowered the estimated glycemic index (eGI). For 20% SPI extruded rice (20SPI-ER), the first-phase rate constant (k₁) of cooked extruded rice was higher than its second-phase (k₂). Conversely, for 20% corn bran extruded rice (20CB-ER), a low value of k₁ and high for k₂ and C_∞2 were found. The 20% RMD extruded rice (20RMD-ER) and the control exhibited a single-phase kinetic digestion with similar k values. The end-point of the second-phase digestion (C_∞2) and the eGI of cooked 20SPI-ER were lower than for fiber addition. These differences were speculated to be due to the heterogeneous matrices of the SPI and CB incorporated kernels, opposed to the homogeneous matrices of the RMD and control. Thus, extruded rice compositions were found that resulted in different starch digestion kinetics [single phase and two-phase (k₁/k₂) high/low, low/high] and were medium eGI with added protein or fiber. Compared to the control, only 20RMD-ER had lower gastric half-emptying time and 20CB-ER had higher subject satisfaction.

Modulation of the Gut Microbiota by Resistant Starch as a Treatment of Chronic Kidney Diseases: Evidence of Efficacy and Mechanistic Insights

Chronic kidney disease (CKD) has been associated with changes in gut microbial ecology, or "dysbiosis," which may contribute to disease progression. Recent studies have focused on dietary approaches to favorably alter the composition of the gut microbial communities as a treatment method in CKD. Resistant starch (RS), a prebiotic that promotes proliferation of gut bacteria such as Bifidobacteria and Lactobacilli, increases the production of metabolites including short-chain fatty acids, which confer a number of health-promoting benefits. However, there is a lack of mechanistic insight into how these metabolites can positively influence renal health. Emerging evidence shows that microbiota-derived metabolites can regulate the incretin axis and mitigate inflammation via expansion of regulatory T cells. Studies from animal models and patients with CKD show that RS supplementation attenuates the concentrations of uremic retention solutes, including indoxyl sulfate and p-cresyl sulfate. Here, we present the current state of knowledge linking the microbiome to CKD, we explore the efficacy of RS in animal models of CKD and in humans with the condition, and we discuss how RS supplementation could be a promising dietary approach for slowing CKD progression.

Acute Effect of Resistant Starch on Food Intake, Appetite and Satiety in Overweight/Obese Males

Several studies have linked increased intake of dietary fibre to improvement in the management of body weight. Dietary fibre from resistant starch (RS) has been shown to have an impact on food intake in normal weight individuals, but its role in obesity is unknown. The present study aimed to investigate the short-term effects of RS on appetite, satiety and postprandial metabolism in overweight/obese subjects. In this single-blind randomized crossover study, overweight/obese healthy males consumed a test breakfast and lunch containing either 48 g RS or a placebo. Postprandial qualitative appetite, glucose, insulin, and GLP-1 were measured every 30 min for 7 h. Energy intake values from an ad libitum dinner and for a 24-h period were assessed. Acute consumption of RS at breakfast/lunch significantly reduced the energy intake at the ad libitum dinner (p = 0.017). No significant effect over 24 h or qualitative feelings of satiety were observed. Significant treatment × time effects were found for postprandial glucose (p = 0.004) for RS compared to placebo, with a trend for higher C-peptide concentrations following RS. The postprandial insulin and GLP-1 responses were not significantly different. RS may indeed have short-term beneficial effects in obese individuals.

Agaricus bisporus supplementation reduces high-fat diet-induced body weight gain and fatty liver development

Obesity is a global epidemic characterized not only by excessive fat deposition but also by important complications such as nonalcoholic liver steatosis. Beneficial antiobesogenic effects have been described for some mushrooms. The current study aimed to demonstrate the protective effect of Agaricus bisporus (AB) supplementation against the metabolic alterations induced by high-fat-diet (HFD) feeding. Eight-week-old C57BL/6J mice were fed for 10 weeks with one of the following diets: (1) control diet (n = 7), (2) HFD (n = 7), (3) HFD supplemented with 5% AB (n = 9), and (4) HFD supplemented with 10% AB (n = 9). A pair-fed group was also included for the 10% AB group (n = 6). The impact of AB supplementation on food intake, body weight gain, and liver and fat pad weights was examined. Biochemical, histological, and molecular parameters were also analyzed. Dietary supplementation with 10% AB reduced the HFD-induced increase in body, epididymal, and mesenteric fat weights (p < 0.01, p < 0.05, and p < 0.05, respectively). Supplementation with AB also reduced liver damage in a dose-dependent manner (p < 0.01 and p < 0.001). This effect was confirmed by histological analysis that showed that liver steatosis was markedly reduced in mice fed with AB. The beneficial properties of 10% AB supplementation appear to be mediated through a decrease in food intake and via stimulation of mesenteric and hepatic free-fatty acid beta-oxidation, along with a decrease in epidydimal and hepatic expression of CD36. In conclusion, supplementation with AB prevents excessive body weight gain and liver steatosis induced by HFD consumption.

Human amylase gene copy number variation as a determinant of metabolic state

INTRODUCTION

Humans have multiple genes encoding amylase that are broadly divided into salivary (AMY1) and pancreatic (AMY2) genes. They exhibit some of the greatest copy numbers of any human gene, an expansion possibly driven by increased dietary starch intake. Within the population, amylase gene copy number is highly variable and there is evidence of an inverse association between AMY1 copy number and BMI.

AREAS COVERED

We examine the evidence for the link between AMY1 and BMI, its potential mechanisms, and the metabolic effects of salivary and pancreatic amylase, both in the gastrointestinal tract and the blood

EXPERT COMMENTARY

Salivary amylase may influence postprandial 'cephalic phase' insulin release, which improves glucose tolerance, while serum amylase may have insulin-sensitizing properties. This could explain the favorable metabolic status associated with higher AMY1 copy number. The association with BMI is harder to explain and is potentially mediated by increased flux of undigested starch into the ileum, with resultant effects on short-chain fatty acids (SCFAs), changes in gut microbiota and effects on appetite and energy expenditure in those with low copy number. Future research on the role of amylase as a determinant of metabolic health and BMI may lead to novel therapies to target obesity.

Role of resistant starch on diabetes risk factors in people with prediabetes: Design, conduct, and baseline results of the STARCH trial

Dietary resistant starch (RS) might alter gastrointestinal tract function in a manner that improves human health, particularly among adults at risk for diabetes. Here, we report the design and baseline results (with emphasis on race differences) from the STARCH trial, the first comprehensive metabolic phenotyping of people with prediabetes enrolled in a randomized clinical trial testing the effect of RS on risk factors for diabetes. Overweight/obese participants (BMI≥27kg/m2 and weight≤143kg), age 35-75y, with confirmed prediabetes were eligible. Participants were randomized to consume 45g/day of RS (RS=amylose) or amylopectin (Control) for 12weeks. The study was designed to evaluate the effect of RS on insulin sensitivity and secretion, ectopic fat, and inflammatory markers. Secondary outcomes included energy expenditure, substrate oxidation, appetite, food intake, colonic microbial composition, fecal and plasma levels of short-chain fatty acids, fecal RS excretion, and gut permeability. Out of 280 individuals screened, 68 were randomized, 65 started the intervention, and 63 were analyzed at baseline (mean age 55y, BMI 35.6kg/m2); 2 were excluded from baseline analyses due to abnormal insulin and diabetes. Sex and race comparisons at baseline were reported. African-Americans had higher baseline acute insulin response to glucose (AIRg measured by frequently sampled intravenous glucose tolerance test) compared to Caucasians, despite having less visceral adipose tissue mass and intrahepatic lipid; all other glycemic variables were similar between races. Sleep energy expenditure was ~90-100kcal/day lower in African-Americans after adjusting for insulin sensitivity and secretion. This manuscript provides an overview of the strategy used to enroll people with prediabetes into the STARCH trial and describes methodologies used in the assessment of risk factors for diabetes. Clinicaltrials.gov identifier: STARCH (NCT01708694). The present study reference can be found here: https://clinicaltrials.gov/ct2/show/NCT01708694. Submission Category: "Study Design, Statistical Design, Study Protocols".

Lotus Seed Resistant Starch Regulates Gut Microbiota and Increases Short-Chain Fatty Acids Production and Mineral Absorption in Mice

Lotus seed resistant starch, known as resistant starch type 3 (LRS3), was orally administered to mice to investigate its effects on the gut microbiota, short-chain fatty acids (SCFAs) production, and mineral absorption. The results showed that mice fed LRS3 displayed a lower level of gut bacterial diversity than other groups. The numbers of starch-utilizing and butyrate-producing bacteria, such as Lactobacillus and Bifidobacterium and Lachnospiraceae, Ruminococcaceae, and Clostridium, respectively, in mice increased after the administration of medium and high doses of LRS3, while those of Rikenellaceae and Porphyromonadaceae decreased. Furthermore, SCFAs and lactic acid in mice feces were affected by LRS3, and lactate was fermented to butyrate by gut microbiota. LRS3 enhanced the intestinal absorption of calcium, magnesium, and iron, and this was dependent on the type and concentration of SCFAs, especially butyrate. Thus, LRS3 promoted the production of SCFAs and mineral absorption by regulating gut microbiota in mice.

Acute Consumption of Resistant Starch Reduces Food Intake but Has No Effect on Appetite Ratings in Healthy Subjects

Previous studies have shown the benefits of native banana starch (NBS) supplementation in improving glucose metabolism and reducing body weight (BW) in humans. However, the effect of this starch on appetite regulation is unknown. The aim of this study was to examine the effects of NBS rich resistant starch on subjective measurements of appetite, energy intake, and appetite hormones in healthy subjects. Postprandial glucose and insulin responses were also assessed. In a randomized, single-blind, crossover study, 28 healthy young subjects consumed a beverage containing either 40 g of NBS or 40 g of digestible corn starch (DCS) on two separate occasions. Effects on appetite were estimated using visual analogue scales (VAS) and satiety hormone responses. At the end of the intervention, participants were provided with a pre-weighed ad libitum homogeneous test meal. After a washout period of 1 week, subjects received the alternative treatment. NBS supplementation induced a reduction in food intake, glucose area under the curve (AUC)-180 min, and insulin AUC-180 min. However, there was no associated effect on the subjective appetite ratings or gut hormones. NBS supplementation may help to reduce meal size and control BW.

Dietary starch intake modifies the relation between copy number variation in the salivary amylase gene and BMI

Background: Studies have shown conflicting associations between the salivary amylase gene (AMY1) copy number and obesity. Salivary amylase initiates starch digestion in the oral cavity; starch is a major source of energy in the diet.Objective: We investigated the association between AMY1 copy number and obesity traits, and the effect of the interaction between AMY1 copy number and starch intake on these obesity traits.Design: We first assessed the association between AMY1 copy number (genotyped by digital droplet polymerase chain reaction) and obesity traits in 4800 individuals without diabetes (mean age: 57 y; 60% female) from the Malmö Diet and Cancer Cohort. Then we analyzed interactions between AMY1 copy number and energy-adjusted starch intake (obtained by a modified diet history method) on body mass index (BMI) and body fat percentage.Results:AMY1 copy number was not associated with BMI (P = 0.80) or body fat percentage (P = 0.38). We observed a significant effect of the interaction between AMY1 copy number and starch intake on BMI (P-interaction = 0.007) and body fat percentage (P-interaction = 0.03). Upon stratification by dietary starch intake, BMI tended to decrease with increasing AMY1 copy numbers in the low-starch intake group (P = 0.07) and tended to increase with increasing AMY1 copy numbers in the high-starch intake group (P = 0.08). The lowest mean BMI was observed in the group of participants with a low AMY1 copy number and a high dietary intake of starch.Conclusions: Our findings suggest an effect of the interaction between starch intake and AMY1 copy number on obesity. Individuals with high starch intake but low genetic capacity to digest starch had the lowest BMI, potentially because larger amounts of undigested starch are transported through the gastrointestinal tract, contributing to fewer calories extracted from ingested starch.

Legume consumption is inversely associated with type 2 diabetes incidence in adults: A prospective assessment from the PREDIMED study

BACKGROUND & AIMS

Legumes, a low-energy, nutrient-dense and low glycemic index food, have shown beneficial effects on glycemic control and adiposity. As such, legumes are widely recommended in diabetic diets, even though there is little evidence that their consumption protects against type 2 diabetes. Therefore the aim of the present study was to examine the associations between consumption of total legumes and specific subtypes, and type 2 diabetes risk. We also investigated the effect of theoretically substituting legumes for other protein- or carbohydrate-rich foods.

METHODS

Prospective assessment of 3349 participants in the PREvención con DIeta MEDiterránea (PREDIMED) study without type 2 diabetes at baseline. Dietary information was assessed at baseline and yearly during follow-up. We used Cox regression models to estimate hazard ratios (HRs) and 95% confidence intervals (95% CIs) for type-2 diabetes incidence according to quartiles of cumulative average consumption of total legumes, lentils, chickpeas, dry beans and fresh peas.

RESULTS

During a median follow-up of 4.3 years, 266 new cases of type 2 diabetes occurred. Individuals in the highest quartile of total legume and lentil consumption had a lower risk of diabetes than those in the lowest quartile (HR: 0.65; 95% CI: 0.43, 0.96; P-trend = 0.04; and HR: 0.67; 95% CI: 0.46-0.98; P-trend = 0.05, respectively). A borderline significant association was also observed for chickpeas consumption (HR 0.68; 95% CI: 0.46, 1.00; P-trend = 0.06). Substitutions of half a serving/day of legumes for similar servings of eggs, bread, rice or baked potato was associated with lower risk of diabetes incidence.

CONCLUSIONS

A frequent consumption of legumes, particularly lentils, in the context of a Mediterranean diet, may provide benefits on type 2 diabetes prevention in older adults at high cardiovascular risk.

TRIAL REGISTRATION

The trial is registered at http://www.controlled-trials.com (ISRCTN35739639). Registration date: 5th October 2005.