Apple and blackcurrant polyphenol-rich drinks decrease postprandial glucose, insulin and incretin response to a high-carbohydrate meal in healthy men and women

Are all sugars equal? Role of the food source in physiological responses to sugars with an emphasis on fruit and fruit juice

High (free) sugar intakes can increase self-reported energy intake and are associated with unfavourable cardiometabolic health. However, sugar source may modulate the effects of sugars due to several mechanisms including the food matrix. The aim of this review was to assess the current state of evidence in relation to food source effects on the physiological responses to dietary sugars in humans relevant to cardiometabolic health. An additional aim was to review potential mechanisms by which food sources may influence such responses. Evidence from meta-analyses of controlled intervention trials was used to establish the balance of evidence relating to the addition of sugars to the diet from sugar-sweetened beverages, fruit juice, honey and whole fruit on cardiometabolic outcomes. Subsequently, studies which have directly compared whole fruit with fruit juices, or variants of fruit juices, were discussed. In summary, the sources of sugars can impact physiological responses, with differences in glycaemic control, blood pressure, inflammation, and acute appetite. Longer-term effects and mechanisms require further work, but initial evidence implicates physical structure, energy density, fibre, potassium and polyphenol content, as explanations for some of the observed responses.

The use of blackcurrant pomace and erythritol to optimise the functional properties of shortbread cookies

As a result of the production of blackcurrant juice, pomace is produced, which is a cheap, easy to further process raw material with high health benefits. The aim of the research was to develop a recipe for shortbread cookies based on blackcurrant pomace (0, 10, 30, 50%) and erythritol, and to assess their nutritional value (content of proteins, fats, sugars, dietary fibre, selected minerals and energy value), pro-health properties (antioxidant and anti-diabetic capacity) and sensory evaluation. The energy value of products with 50% of pomace sweetened with erythritol was nearly 30% lower compared to traditional cookies, while the content of dietary fibre was 10 times higher in products with the highest percentage of pomace. The antioxidant capacity and the total content of polyphenolic compounds increased with the increase in pomace content. The ability to inhibit α-amylase by shortbread cookies without pomace was about 400 times lower than those with 50% pomace. The results of the sensory evaluation showed that erythritol-sweetened cookies have more desirable characteristics compared to sucrose-sweetened cookies. Finally, it was proved that the proposed products are an excellent proposal for people struggling with food-dependent diseases, as well as being an opportunity to manage waste from the fruit industry.

Natural Functional Beverages as an Approach to Manage Diabetes

Diabetes mellitus is a chronic disease, commonly associated with unhealthy habits and obesity, and it is becoming a serious health issue worldwide. As a result, new approaches to treat diabetes are required, and a movement towards more natural approaches is emerging. Consuming fruit and vegetables is advised to prevent diabetes since they contain several bioactive compounds. A simple and effective strategy to include them in the diets of diabetic and obese people is through beverages. This review aims to report the anti-diabetic potentials of different vegetable and fruit beverages. These functional beverages demonstrated in vitro potential to inhibit α-glucosidase and α-amylase enzymes and to improve glucose uptake. In vivo, beverage consumption showed a reduction of blood glucose, increase of insulin tolerance, improvement of lipid profile, control of obesity, and reduction of oxidative stress. This suggests the potential of vegetable- and fruit-based functional beverages to be used as a natural innovative therapy for the management of diabetes.

Acute effects of drinks containing blackcurrant and citrus (poly)phenols and dietary fibre on postprandial glycaemia, gut hormones, cognitive function and appetite in healthy adults: two randomised controlled trials

(Poly)phenol (PP)-rich blackcurrant (BC) extracts reduce postprandial glucose concentrations. Combinations with other fruit (poly)phenols and fruit fibre may enhance the effect. This study investigated the acute effects of combinations of BC extracts, high (H-BC) and low (L-BC) (poly)phenol concentrations, sweet orange extracts (SO) and fibre-rich orange pulp (F) in reducing postprandial glycaemia. In two randomised, double-blind, crossover design studies, healthy participants consumed seven types of 200 mL beverages: in the GLU-FX trial, H-BC (1600 mg PP); L-BC (800 mg PP); SO (800 mg PP); BC + SO (1600 mg PP) or CON (placebo); in the GLU-MIX trial, BC + F (800 mg PP), F (1.5 g fibre), or CON2 (placebo), immediately followed by consumption of 75 g available carbohydrate (starch and sugars). Blood was sampled at baseline and postprandially to measure changes in glucose, insulin, and gut hormones; appetite changes were assessed by visual analogue scales and, in GLU-MIX, ad libitum food intake and cognitive function were assessed. Twenty-nine and thirty-seven adults completed GLU-FX and GLU-MIX, respectively. L-BC reduced early postprandial glycaemia (0-30 min) with no differences in glucose incremental Cmax or total glycaemic response. No significant effect was observed following other drinks relative to CON. L-BC and H-BC drinks inhibited insulin secretion up to 30 min and GIP up to 120 min. In GLU-MIX, BC + F improved some indicators of cognitive function but not all. Measures of appetite were unaffected. The impact of (poly)phenol-rich BC extracts on total postprandial glycaemia in healthy participants was minimal and not enhanced when administered in combination with an orange (poly)phenol extract or orange pulp. Clinical Trials registered at https://www.clinicaltrials.gov: NCT03184064 (GLU-FX) and NCT03572296 (GLU-MIX).

Effect of (poly)phenol-rich 'Daux Belan' apple supplementation on diet-induced obesity and glucose intolerance in C57BL/6NCrl mice

Obesity is a state of metabolic dysfunction that can lead to dyslipidemia and impaired glucose homeostasis. Apple polyphenols have been shown to ameliorate dyslipidemia/metabolic dysfunction in humans. The influence of apple (poly)phenols on energy metabolism in high-fat (HF) diet-induced obese mice remains controversial. This study examined the effect of dietary supplementation of (poly)phenol-rich 'Daux Belan' apple (DB; 6.2 mg gallic acid equivalence (GAE)/mouse/day; 0.15% (poly)phenol) in the form of freeze-dried powder on glucose and lipid metabolism in male HF-fed C57BL/6NCrl mice, in comparison to low-(poly)phenol-containing 'Zestar' apple (Z; 0.4 mg GAE/mouse/day). Obesity, glucose intolerance, hypertriglyceridemia, and hepatic lipid vacuolation were induced by HF feeding while circulating cholesterol levels remained unchanged. DB apple supplementation did not protect against HF-induced body weight gain, hyperglycemia, hepatic triglyceride level elevation, and hepatic lipid vacuolation at the tested dosage. Future studies should be conducted with increased DB dosage and employ apple (poly)phenols supplemented in the form of extracts or sugar-free powder.

Anti-Hyperglycemic Effects of Bioactive Compounds in the Context of the Prevention of Diet-Related Diseases

Diet-related diseases are health conditions primary caused by poor nutrition. These diseases encompass obesity, type 2 diabetes, cardiovascular diseases, osteoporosis, and certain types of cancer. Functional foods and nutraceuticals offer a promising dietary approach to addressing diet-related diseases across various clinical contexts. The bioactive compounds found in these foods are the subject of intensive studies aimed at discovering their anti-hyperglycemic effects, which are beneficial in alleviating chronic diseases and protecting human health. Hyperglycemia is a common risk factor for metabolic disease and mortality worldwide. Chronic hyperglycemic states can lead to many long-term complications, such as retinopathy, neuropathy, kidney disease, heart disease, cancer, and diabetes. This review explores the potential anti-hyperglycemic effects of bioactive compounds, specifically flavonoids and phenolic acids, and their proposed roles in mitigating chronic diseases and promoting human health. By thoroughly examining the existing literature, we investigated the potential anti-hyperglycemic effects of these bioactive compounds and their proposed roles in managing chronic diseases. The goal of this paper was to enhance our comprehension of how these compounds modulate glucose transporters, with the ultimate aim of identifying effective strategies for the prevention and treatment of diet-related diseases. Overall, this review investigated the use of bioactive compounds from functional foods as potential inhibitors of glucose transporters in the context of prevention/treatment of diet-related diseases.

Anti-Diabetic Potential of Polyphenol-Rich Fruits from the Maleae Tribe-A Review of In Vitro and In Vivo Animal and Human Trials

The Maleae tribe consists of over one thousand species, including many well-known polyphenol-containing fruit crops with wide-ranging biological properties, e.g., apples (Malus), chokeberries (Aronia), pears (Pyrus), quinces (Cydonia, Chaenomeles), saskatoon (Amelanchier), loquats (Eriobotrya), medlars (Mespilus), rowans (Sorbus), and hawthorns (Crataegus). Considering the current interest in the concept of functional foods and the still-insufficient methods of diabetes management, the anti-diabetic potential of fruits has been studied intensively, including those of the Maleae tribe. This paper is the first comprehensive overview of this selected topic, covering articles published from 2000 to 2023 (131 articles in total). The first part of this review focuses on the potential mechanisms of action of fruits investigated so far (46 species), including their effects on tissue-specific glucose transport and the expression or activity of proteins in the insulin signalling pathway. The second part covers the phytocompounds responsible for particular fruits' activity-primarily polyphenols (e.g., flavonols, dihydrochalcones, proanthocyanidins, anthocyanins, phenolic acids), but also polysaccharides, triterpenes, and their additive and synergistic effects. In summary, fruits from the Maleae tribe seem promising as functional foods and anti-diabetic agents; however, their prospects for more expansive pro-health application require further research, especially more profound in vivo trials.

Effect of Blackcurrant Consumption on the Genitourinary System: A Literature Review

Both in vivo and in vitro studies have shown that functional plant-based food such as fruits, vegetables, and berries can enhance health, have preventive effects, and reduce the risk of several chronic diseases. This review discusses blackcurrant fruit usage in humans and experimental animals and its effect on the genitourinary system (GUS). This comprehensive review demonstrates that blackcurrants and their bioactive compounds possess medicinal and therapeutic properties related to the GUS. Emphasis in the literature has been placed on the bioavailability of the active blackcurrant components. Nonetheless, future clinical trials are needed to investigate and improve the bioavailability of blackcurrant phenolic compounds, such as anthocyanins, and to expand the evidence that active blackcurrant compounds can treat various genitourinary diseases.

Apple juice relieves loperamide-induced constipation in rats by downregulating the intestinal apical sodium-dependent bile acid transporter ASBT

Apples are known to exhibit various beneficial effects on human health. In the present study, we investigated the effect of continuous intake of apple juice (AJ) on constipation status. A single dose of loperamide in rats as the constipation model markedly decreased the weight and number of fecal pellets compared to saline-administered rats as a control. After the administration of AJ twice a day for seven days, recovery of defecation close to that of the control was observed in loperamide-treated rats. In addition, the total bile acid content in the feces increased from day 4 after the administration of AJ. Among hepatic and intestinal transporters and enzymes that regulate bile acids, the mRNA expression of the apical sodium-dependent bile acid transporter (Asbt, slc10a2) was decreased by AJ in rats. Furthermore, the Asbt-mediated bile acid transport activity in the rat ileum decreased after AJ administration. Moreover, in human colonic cancer-derived Caco-2 cells, AJ exposure for 24 and 48 h decreased the expressions of ASBT mRNA and protein, and the uptake activity of taurocholic acid in both 7- and 21-d cultures. Several components of AJ, such as procyanidins, decreased the expression of ASBT in Caco-2 cells. In conclusion, ASBT downregulation is a possible mechanism responsible for the constipation-relieving effect of apples, and procyanidins may play a role in downregulating ASBT, which leads to the beneficial effects of apples against constipation. Although it is generally agreed that the common dietary compositions play a role in constipation relief, the novel specific mechanism of apples found in this study would facilitate understanding food functions.

Venom Peptides, Polyphenols and Alkaloids: Are They the Next Antidiabetics That Will Preserve β-Cell Mass and Function in Type 2 Diabetes?

Improvement of insulin secretion by pancreatic β-cells and preservation of their mass are the current challenges that future antidiabetic drugs should meet for achieving efficient and long-term glycemic control in patients with type 2 diabetes (T2D). The successful development of glucagon-like peptide 1 (GLP-1) analogues, derived from the saliva of a lizard from the Helodermatidae family, has provided the proof of concept that antidiabetic drugs directly targeting pancreatic β-cells can emerge from venomous animals. The literature reporting on the antidiabetic effects of medicinal plants suggests that they contain some promising active substances such as polyphenols and alkaloids, which could be active as insulin secretagogues and β-cell protectors. In this review, we discuss the potential of several polyphenols, alkaloids and venom peptides from snake, frogs, scorpions and cone snails. These molecules could contribute to the development of new efficient antidiabetic medicines targeting β-cells, which would tackle the progression of the disease.

Thinned young apple polyphenols may prevent neuronal apoptosis by up-regulating 5-hydroxymethylcytosine in the cerebral cortex of high-fat diet-induced diabetic mice

Apple polyphenols exert neuroprotective effects by improving the mitochondrial tricarboxylic acid (TCA) cycle function, but the details of their mechanisms are still not fully understood. TCA cycle metabolites regulate the level of 5-hydroxymethylcytosine (5hmC) by affecting the ten-eleven translocation (TET) enzyme activity. Therefore, we hypothesized that thinned young apple polyphenols (TYAPs) inhibit neuronal apoptosis by up-regulating the level of 5hmC in the cerebral cortex of high-fat diet-induced diabetic mice. C57BL/6J mice were randomly divided into 5 groups (n = 10 each group): the control (CON) group, the high-fat diet (HFD, negative control) group, the lovastatin (LOV, positive drug control) group, the resveratrol (RES, positive polyphenol control) group and the TYAP group during an eight-week intervention. The presented results verified that in the HFD group, the level of 5hmC and the expression of TET2 in the cerebral cortex were significantly lower, and the ratio of (succinic acid + fumaric acid)/α-ketoglutarate and the neuronal apoptosis rate were significantly higher than those in the CON group. However, TYAP intervention effectively restored the level of 5hmC through up-regulating the expression and activity of TET2, so as to improve diabetes symptoms and prevent diabetes-induced neuronal apoptosis.

Chronic consumption of probiotics, oats, and apples has differential effects on postprandial bile acid profile and cardiometabolic disease risk markers compared with an isocaloric control (cornflakes): a randomized trial

BACKGROUND

Dietary components that impact the gut microbiota may beneficially affect cardiometabolic health, possibly by altered bile acid metabolism. However, impacts of these foods on postprandial bile acids, gut microbiota, and cardiometabolic risk markers are unclear.

OBJECTIVES

The aim of this study was to determine the chronic effects of probiotics, oats, and apples on postprandial bile acids, gut microbiota, and cardiometabolic health biomarkers.

METHODS

Using an acute within chronic parallel design, 61 volunteers (mean ± SD: age 52 ± 12 y; BMI 24.8 ± 3.4 kg/m²) were randomly assigned to consume 40 g cornflakes (control), 40 g oats or 2 Renetta Canada apples each with 2 placebo capsules per day or 40 g cornflakes with 2 Lactobacillus reuteri capsules (>5 × 10⁹ CFU) per day, for 8 wk. Fasting and postprandial serum/plasma bile acids and cardiometabolic health biomarkers, fecal bile acids, and gut microbiota composition were determined.

RESULTS

At week 0, oats and apples significantly decreased postprandial serum insulin [area under the curve (AUC): 25.6 (17.4, 33.8) and 23.4 (15.4, 31.4) vs. 42.0 (33.7, 50.2) pmol/L × min and incremental AUC (iAUC): 17.8 (11.6, 24.0) and 13.7 (7.7, 19.8) vs. 29.6 (23.3, 35.8) pmol/L × min] and C-peptide responses [AUC: 599 (514, 684) and 550 (467, 632) vs. 750 (665, 835) ng/mL × min], whereas non-esterified fatty acids were increased [AUC 135 (117, 153) vs. 86.3 (67.9, 105) and iAUC 96.2 (78.8, 114) vs. 60 (42.1, 77.9) mmol/L × min] after the apples vs. control (P ≤ 0.05). Postprandial unconjugated [AUC: predicted means (95% CI) 1469 (1101, 1837) vs. 363 (-28, 754) μmol/L × min and iAUC: 923 (682, 1165) vs. 22.0 (-235, 279) μmol/L × min)] and hydrophobic [iAUC: 1210 (911, 1510) vs. 487 (168, 806) μmol/L × min] bile acid responses were increased after 8 wk probiotic intervention vs. control (P ≤ 0.049). None of the interventions modulated the gut microbiota.

CONCLUSIONS

These results support beneficial effects of apples and oats on postprandial glycemia and the ability of the probiotic Lactobacillus reuteri to modulate postprandial plasma bile acid profiles compared with control (cornflakes), with no relationship evident between circulating bile acids and cardiometabolic health biomarkers.

Anthocyanin actions at the gastrointestinal tract: Relevance to their health benefits

Anthocyanins (AC) are flavonoids abundant in the human diet, which consumption has been associated to several health benefits, including the mitigation of cardiovascular disease, type 2 diabetes, non-alcoholic fatty liver disease, and neurological disorders. It is widely recognized that the gastrointestinal (GI) tract is not only central for food digestion but actively participates in the regulation of whole body physiology. Given that AC, and their metabolites reach high concentrations in the intestinal lumen after food consumption, their biological actions at the GI tract can in part explain their proposed local and systemic health benefits. In terms of mechanisms of action, AC have been found to: i) inhibit GI luminal enzymes that participate in the absorption of lipids and carbohydrates; ii) preserve intestinal barrier integrity and prevent endotoxemia, inflammation and oxidative stress; iii) sustain goblet cell number, immunological functions, and mucus production; iv) promote a healthy microbiota; v) be metabolized by the microbiota to AC metabolites which will be absorbed and have systemic effects; and vi) modulate the metabolism of GI-generated hormones. This review will summarize and discuss the latest information on AC actions at the GI tract and their relationship to overall health benefits.

Anthocyanins: Potential Therapeutic Approaches towards Obesity and Diabetes Mellitus Type 2

Overweight and obesity are present in about three-quarters of the adult population in Mexico. The inflammatory mechanisms subjacent to visceral white adipose tissue are accountable for the initiation and development of cardiometabolic alterations, including type 2 diabetes. Lifestyle changes are pillars within its therapeutics and, thus, current dietary modifications should include not only hypocaloric prescriptions with balanced macronutrient intake, preferably by increasing the amount of whole grains, fruits, vegetables, nuts and legumes, but in concomitance, bioactive substances, such as anthocyanins, have been correlated with lower incidence of this disease.

Nutritional strategies to attenuate postprandial glycemic response

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

Anti-Obesity Evaluation of Averrhoa carambola L. Leaves and Assessment of Its Polyphenols as Potential α-Glucosidase Inhibitors

Averrhoa carambola L. is reported for its anti-obese and anti-diabetic activities. The present study aimed to investigate its aqueous methanol leaf extract (CLL) in vivo anti-obese activity along with the isolation and identification of bioactive compounds and their in vitro α-glucosidase inhibition assessment. CLL improved all obesity complications and exhibited significant activity in an obese rat model. Fourteen compounds, including four flavone glycosides (1–4) and ten dihydrochalcone glycosides (5–12), were isolated and identified using spectroscopic techniques. New compounds identified in planta included (1) apigenin 6-C-(2-deoxy-β-D-galactopyranoside)-7-O-β-D-quinovopyranoside, (8) phloretin 3′-C-(2-O-(E)-cinnamoyl-3-O-β-D-fucopyranosyl-4-O-acetyl)-β-D-fucopyranosyl-6′-O-β-D fucopyranosyl-(1/2)-α-L arabinofuranoside, (11a) phloretin3′-C-(2-O-(E)-p-coumaroyl-3-O-β-D-fucosyl-4-O-acetyl)-β-D-fucosyl-6′-O-(2-O-β-D-fucosyl)-α-L-arabinofuranoside, (11b) phloretin3′-C-(2-O-(Z)-p-coumaroyl-3-O-β-D-fucosyl-4-O-acetyl)-β-D-fucosyl-6′-O-(2-O-β-D-fucosyl)-α-L-arabinofuranoside. Carambolaside M (5), carambolaside Ia (6), carambolaside J (7), carambolaside I (9), carambolaside P (10a), carambolaside O (10b), and carambolaside Q (12), which are reported for the first time from A. carambola L. leaves, whereas luteolin 6-C-α-L-rhamnopyranosyl-(1-2)-β-D-fucopyranoside (2), apigenin 6-C-β-D-galactopyranoside (3), and apigenin 6-C-α-L-rhamnopyranosyl-(1-2)-β-L-fucopyranoside (4) are isolated for the first time from Family. Oxalidaceae. In vitro α-glucosidase inhibitory activity revealed the potential efficacy of flavone glycosides, viz., 1, 2, 3, and 4 as antidiabetic agents. In contrast, dihydrochalcone glycosides (5–11) showed weak activity, except for compound 12, which showed relatively strong activity.

Metabolic and Cardiovascular Benefits of Apple and Apple-Derived Products: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background

Quantitative evidence of the metabolic and cardiovascular effects of apples (Malus domestica) is lacking in interventional studies. This study aimed to summarize the available evidence of the beneficial effects of apples and apple-derived products (ADPs) on metabolic and cardiovascular markers.

Methods

Peer-reviewed randomized controlled trials (RCTs) were identified from four databases on May 3, 2021 and regularly updated until the end of May 2021. Demographic characteristics, intervention types, and evaluation parameters were extracted. A meta-analysis on the mean difference of change scores was conducted on commonly presented outcomes in the RCTs.

Results

The metabolic and cardiovascular effects of diverse regimens, including whole apple, apple extract, and apple juice, were examined in 18 eligible RCTs. Nine common evaluation outcomes were eventually introduced to the meta-analysis, including total cholesterol (TC), low-density lipoprotein (LDL), high-density lipoprotein (HDL), triglyceride, glucose, insulin, C-reactive protein, and systolic/diastolic blood pressures. The levels of TC (−2.69 mg/dL; 95% CI: −5.43, 0.04 mg/dL) and LDL (−2.80 mg/dL; 95% CI: −5.78, 0.17 mg/dL) showed a non-significant decreasing tendency after at least a week of apple consumption. Further subgroup analysis, particularly, a comparison with placebo as a control, showed a significant reduction in TC and LDL levels. When stratified by the baseline level, subjects with high TC and LDL level were shown to have more benefits from the apple intake. Intriguingly, apple and ADPs significantly reduced HDL levels to a small extent (−1.04 mg/dL; 95% CI: −1.79, −0.29 mg/dL). The other markers were mostly unaffected by the intervention.

Conclusion

Our investigation revealed that apples could improve blood cholesterol levels.

Systematic Review Registration

[https://www.crd.york.ac.uk/prospero/], identifier [CRD42020215977].

Inhibitory Effects against Alpha-Amylase of an Enriched Polyphenol Extract from Pericarp of Mangosteen (Garcinia mangostana)

The pericarp of mangosteen, a by-product of the mangosteen, is rich in polyphenols. In this study, an efficient and environmentally friendly method for preparative enrichment of polyphenols from mangosteen pericarp (MPPs) was developed, and the inhibitory effects on starch digestion were also evaluated. It was found that the optimal extract method of MPPs was at a solid to solvent ratio of 1:50 g/mL, pH of 2, and at 80 °C for 2 h. The IC₅₀ of MPPs for α-amylase was 0.28 mg/mL. Based on the fluorescence quenching results, we presumed that MPPs could alter the natural structure of α-amylase, resulting in inhibitory activity on α-amylase. In addition, MPPs significantly reduced the blood glucose peak and AUC of glucose responses in rats after ingestion of the starch solution. Taken together, MPPs may have the potential as a functional supplement for blood glucose control and diabetes prevention.

The Role of Nutraceutical Containing Polyphenols in Diabetes Prevention

Research in pharmacological therapy has led to the availability of many antidiabetic agents. New recommendations for precision medicine and particularly precision nutrition may greatly contribute to the control and especially to the prevention of diabetes. This scenario greatly encourages the search for novel non-pharmaceutical molecules. In line with this, the daily and long-term consumption of diets rich in phenolic compounds, together with a healthy lifestyle, may have a protective role against the development of type 2 diabetes. In the framework of the described studies, there is clear evidence that the bio accessibility, bioavailability, and the gut microbiota are indeed affected by: the way phenolic compounds are consumed (acutely or chronically; as pure compounds, extracts, or in-side a whole meal) and the amount and the type of phenolic compounds (ex-tractable or non-extractable/macromolecular antioxidants, including non-bioavailable polyphenols and plant matrix complexed structures). In this review, we report possible effects of important, commonly consumed, phenolic-based nutraceuticals in pre-clinical and clinical diabetes studies. We highlight their mechanisms of action and their potential effects in health promotion. Translation of this nutraceutical-based approach still requires more and larger clinical trials for better elucidation of the mechanism of action toward clinical applications.

Flavonoid constituents of Amomum tsao-ko Crevost et Lemarie and their antioxidant and antidiabetic effects in diabetic rats - in vitro and in vivo studies

Amomum tsao-ko Crevost et Lemarie (A. tsao-ko) is a well-known dietary spice and traditional Chinese medicine. This study aimed to identify the flavonoids in A. tsao-ko and evaluate their antioxidant and antidiabetic activities in in vitro and in vivo studies. A. tsao-ko methanol extracts possessed a high flavonoid content (1.21 mg QE per g DW) and a total of 29 flavonoids were identified by employing UPLC-MS/MS. In vitro, A. tsao-ko demonstrated antioxidant activity (ORAC value of 34276.57 μM TE/100 g DW, IC₅₀ of ABTS of 3.49 mg mL^-1 and FRAP value of 207.42 μM Fe²⁺ per g DW) and α-amylase and α-glucosidase inhibitory ability with IC₅₀ values of 14.23 and 1.76 mg mL^-1, respectively. In vivo, type 2 diabetes mellitus (T2DM) models were induced by a combined high-fat diet (HFD) and streptozotocin (STZ) injection in rats. Treatment with the A. tsao-ko extract (100 mg freeze-dried powder per kg bw) for 6 weeks could significantly improve impaired glucose tolerance, decrease the levels of fasting blood glucose (FBG), insulin, and malondialdehyde (MDA), and increase the superoxide dismutase (SOD) level. Histopathology revealed that the A. tsao-ko extract preserved the architecture and function of the pancreas. In conclusion, the flavonoid composition of A. tsao-ko exhibits excellent antioxidant and antidiabetic activity in vitro and in vivo. A. tsao-ko could be a novel natural material and developed as a related functional food and medicine in T2DM management.

Food phenolics stimulate adipocyte browning via regulating gut microecology

Fat browning has piqued the interest of researchers as a potential target for treating obesity and related metabolic disorders. Recruitment of brown adipocytes leads to enhanced energy dissipation and reduced adiposity, thus facilitating the maintenance of metabolic homeostasis. Evidence is increasing to support the crucial roles of polyphenols and gut microecology in turning fat "brown". However, it is not clear whether the intestinal microecology is involved in polyphenol-mediated regulation of adipose browning, so this concept is worthy of exploration. In this review, we summarize the current knowledge, mostly from studies with murine models, supporting the concept that the effects of food phenolics on brown fat activation and white fat browning can be attributed to their regulatory actions on gut microecology, including microbial community profile, gut metabolites, and gut-derived hormones. Furthermore, the potential underlying pathways involved are also discussed. Basically, understanding gut microecology paves the way to determine the underlying roles and mechanisms of food phenolics in adipose browning.

Proanthocyanidins and Where to Find Them: A Meta-Analytic Approach to Investigate Their Chemistry, Biosynthesis, Distribution, and Effect on Human Health

Proanthocyanidins (PACs) are a class of polyphenolic compounds that are attracting considerable interest in the nutraceutical field due to their potential health benefits. However, knowledge about the chemistry, biosynthesis, and distribution of PACs is limited. This review summarizes the main chemical characteristics and biosynthetic pathways and the main analytical methods aimed at their identification and quantification in raw plant matrices. Furthermore, meta-analytic approaches were used to identify the main plant sources in which PACs were contained and to investigate their potential effect on human health. In particular, a cluster analysis identified PACs in 35 different plant families and 60 different plant parts normally consumed in the human diet. On the other hand, a literature search, coupled with forest plot analyses, highlighted how PACs can be actively involved in both local and systemic effects. Finally, the potential mechanisms of action through which PACs may impact human health were investigated, focusing on their systemic hypoglycemic and lipid-lowering effects and their local anti-inflammatory actions on the intestinal epithelium. Overall, this review may be considered a complete report in which chemical, biosynthetic, ecological, and pharmacological aspects of PACs are discussed.

Age-Related Cognitive Decline May Be Moderated by Frequency of Specific Food Products Consumption

Our study aimed to evaluate whether the type of food products and the frequency of their consumption are associated with cognitive functioning in younger and older adults. The impact of diets that are high in added sugars and saturated fat on cognitive functioning, especially on memory, was at the center of our interest. Participants in the study were 204 healthy adults (aged 20-55) who performed a multitasking cognitive test and completed dietary and psychological questionnaires. Stepwise regression analysis with age and food consumption patterns as predictors, and the cognitive task performance as a dependent variable, revealed that cognitive task performance worsened with age. However, we found that the frequency of consuming different types of foods (healthy versus unhealthy dietary patterns) moderates the effects of age on cognitive functioning. Red meat and animal fat consumption were negatively correlated with cognitive performance, and this relation was dependent on the age of our participants. Conversely, white meat and fish consumption were positively related to memory. Different indices of dietary patterns (both positive and negative) were stronger predictors of cognitive performance in the older adult group. We interpret our results as evidence that diet may be a protective (or worsening) factor in age-related cognitive decline.

Sweet potato (Ipomoea batatas L.) leaf polyphenols ameliorate hyperglycemia in type 2 diabetes mellitus mice

The hypoglycemic effects and potential mechanism of sweet potato leaf polyphenols (SPLP) on type 2 diabetes mellitus (T2DM) were investigated. Results showed that oral administration of SPLP to mice could alleviate body weight loss, decrease fasting blood glucose levels (by 64.78%) and improve oral glucose tolerance compared with those of untreated diabetic mice. Furthermore, increased fasting serum insulin levels (by 100.11%), ameliorated insulin resistance and improved hepatic glycogen (by 126.78%) and muscle glycogen (increased by 135.85%) were observed in the SPLP treatment group. SPLP also could reverse dyslipidemia, as indicated by decreased total cholesterol, triglycerides, low density lipoprotein-cholesterol and promoted high density lipoprotein-cholesterol. Histopathological analysis revealed that SPLP could relieve liver inflammation and maintain the islet structure to inhibit β-cell apoptosis. A quantitative real-time polymerase chain reaction confirmed that SPLP could up-regulate the phosphatidylinositol 3-kinase/protein kinase B/glycogen synthase kinase-3β signaling pathway to improve glucose metabolism and up-regulate the phosphatidylinositol 3-kinase/protein kinase B/glucose transporter 4 signaling pathway in the skeletal muscle to enhance glucose transport. This study provides useful information to support the application of SPLP as a natural product for the treatment of T2DM.

Potential of Beetroot and Blackcurrant Compounds to Improve Metabolic Syndrome Risk Factors

Metabolic syndrome (MetS) is a group of metabolic abnormalities, which together lead to increased risk of coronary heart disease (CHD) and type 2 diabetes mellitus (T2DM), as well as reduced quality of life. Dietary nitrate, betalains and anthocyanins may improve risk factors for MetS and reduce the risk of development of CHD and T2DM. Beetroot is a rich source of dietary nitrate, and anthocyanins are present in high concentrations in blackcurrants. This narrative review considers the efficacy of beetroot and blackcurrant compounds as potential agents to improve MetS risk factors, which could lead to decreased risk of CHD and T2DM. Further research is needed to establish the mechanisms through which these outcomes may occur, and chronic supplementation studies in humans may corroborate promising findings from animal models and acute human trials.

Polyphenols Rich Diets and Risk of Type 2 Diabetes

Type 2 diabetes is an increasing health concern worldwide. Both genetic and environmental risk factors as improper dietary habits or physical inactivity are known to be crucial in the pathogenesis of type 2 diabetes. Polyphenols are a group of plant-derived compounds with anti-inflammatory and antioxidant properties that are associated with a low prevalence of metabolic conditions characterized by insulin resistance, including obesity, diabetes, and hypertension. Moreover, there is now full awareness that foods that are rich in phytochemicals and polyphenols could play an important role in preserving human cardiovascular health and substantial clinical evidence indicates that regular dietary consumption of such foods affects favorably carbohydrate metabolism. This review briefly summarizes the evidence relating dietary patterns rich in polyphenols with glucose metabolism and highlights the potential benefits of these compounds in the prevention of type 2 diabetes.

The Anti-Inflammatory Properties of Phytochemicals and Their Effects on Epigenetic Mechanisms Involved in TLR4/NF-κB-Mediated Inflammation

Innate immune response induces positive inflammatory transducers and regulators in order to attack pathogens, while simultaneously negative signaling regulators are transcribed to maintain innate immune homeostasis and to avoid persistent inflammatory immune responses. The gene expression of many of these regulators is controlled by different epigenetic modifications. The remarkable impact of epigenetic changes in inducing or suppressing inflammatory signaling is being increasingly recognized. Several studies have highlighted the interplay of histone modification, DNA methylation, and post-transcriptional miRNA-mediated modifications in inflammatory diseases, and inflammation-mediated tumorigenesis. Targeting these epigenetic alterations affords the opportunity of attenuating different inflammatory dysregulations. In this regard, many studies have identified the significant anti-inflammatory properties of distinct naturally-derived phytochemicals, and revealed their regulatory capacity. In the current review, we demonstrate the signaling cascade during the immune response and the epigenetic modifications that take place during inflammation. Moreover, we also provide an updated overview of phytochemicals that target these mechanisms in macrophages and other experimental models, and go on to illustrate the effects of these phytochemicals in regulating epigenetic mechanisms and attenuating aberrant inflammation.

Food Matrix and Macronutrient Digestion

Food digestion may be regarded as a physiological interface between food and health. During digestion, the food matrix is broken down and the component nutrients and bioactive compounds are absorbed through a synergy of mechanical, chemical, and biochemical processes. The food matrix modulates the extent and kinetics to which nutrients and bioactive compounds make themselves available for absorption, hence regulating their concentration profile in the blood and their utilization in peripheral tissues. In this review, we discuss the structural and compositional aspects of food that modulate macronutrient digestibility in each step of digestion. We also discuss in silico modeling approaches to describe the effect of the food matrix on macronutrient digestion. The detailed knowledge of how the food matrix is digested can provide a mechanistic basis to elucidate the complex effect of food on human health and design food with improved functionality.

Polyphenols in foods: Classification, methods of identification, and nutritional aspects in human health

Polyphenols widely exists in various foods, including main crops, fruits, beverages and some wines. Famous representatives of polyphenols, such as resveratrol in red wine, (-)-epigallocatechin gallate in green tea, chlorogenic acid in coffee, anthocyanins in colored fruits, procyanidins in grape seed have become hot research topics in food science and nutrition. There have been thousands of papers on the biochemistry, chemistry, nutritional values and population-based investigations of dietary polyphenols. In this chapter, we reviewed the published articles and database of dietary polyphenols to draw a profile for the classification, structural identification, and biological activities mainly based on enzymes, cell bioassay and animal models, as well as the population-based investigation results. The typical compound and its health benefits for each category of polyphenols was also introduced. The identification of dietary polyphenols could be solved by combined spectroscopy methods, of which the liquid chromatography tandem mass spectrometry is highlighted to greatly increase the efficiency on structural identification. Although the population-based investigation showed some controversial results for health benefits, the multi-functions of dietary polyphenols on preventing metabolic syndromes, various cancers and neurodegenerative disease have attracted much attention.

Health benefits of cyanidin-3-glucoside as a potent modulator of Nrf2-mediated oxidative stress

Berries are natural sources of anthocyanins, especially cyanidin-3-glucoside (C3G), and exhibit significant antioxidant, antidiabetic, anti-inflammatory, and cytoprotective effects against various oxidative stress-induced disorders. C3G and its metabolites possess higher absorption and bioavailability, and interaction with gut microbiota may enhance their health benefits. Various in vitro studies have shown the reactive oxygen species (ROS)-mitigating potential of C3G. However, in in vivo models, C3G exerts its cytoprotective properties by regulating the nuclear factor erythroid 2-related factor 2 (Nrf2)/antioxidant-responsive element (ARE) pathway. Despite existing reports stating various health benefits of C3G, its antioxidant potential by modulating the Nrf2 pathway remains less identified. This review discusses the Nrf2-mediated antioxidant response of C3G in modulating oxidative stress against DNA damage, apoptosis, carcinogen toxicity, and inflammatory conditions. Furthermore, we have reviewed the recent clinical trial data to establish cross talk between a berry-rich diet and disease prevention.

Insight into the potential application of polyphenol-rich dietary intervention in degenerative disease management

In recent times, a great number of plants have been studied in order to identify new components with nutraceutical properties, among which are polyphenols. Dietary polyphenols represent a large group of bioactive molecules widely found in the food of plant origin and they have been found able to prevent the onset and progression of degenerative diseases, and to reduce and control their symptoms. These health protective effects have been mainly related to their antioxidant and anti-inflammatory properties. However, it must be considered that the application of isolated polyphenols as nutraceuticals is quite limited due to their poor systemic distribution and relative bioavailability. The present review highlights the potential effect of dietary intervention with polyphenol-rich food and plant extracts in patients with cancer, diabetes and neurodegenerative, autoimmune, cardiovascular and ophthalmic diseases, as well as the possible molecular mechanisms of action suggested in numerous studies with animal models.

Functionalization of whey protein isolate fortified with blackcurrant concentrate by spray-drying and freeze-drying strategies

A solution of whey protein isolate was combined with blackcurrant concentrate via spray-drying and freeze-drying techniques separately to develop novel protein ingredients, (SWB and FWB). Chemical compositions, colour profiles, total anthocyanin content and encapsulation efficacy of the protein ingredients were evaluated. An in vitro digestion process was employed to observe the changes in total phenolic content, antioxidant activity, and predictive in vitro glycaemic response of the protein ingredients. The half maximal inhibitory concentration (IC₅₀) towards α-Amylase, and a molecular docking study on the interactions of α-Amylase with anthocyanins, were both performed to investigate the potential mechanisms of hypoglycaemic properties of these protein ingredients. The protein contents of SWB and FWB were 67.94 ± 0.47% and 68.16 ± 0.77%, respectively. Blackcurrant concentrate significantly (p < 0.001) changed the colour profiles of whey protein isolate. SWB obtained a higher total phenol content (3711.28 ± 4.36 μg/g), total anthocyanin content (85390.80 ± 162.81 μg/100 g), and greater encapsulation efficacy (99.64 ± 0.16%) than those of FWB (3413.03 ± 20.60 μg/g, 64230.24 ± 441.08 μg/100 g, and 95.43 ± 0.14%, respectively). Total phenolic content and antioxidant activities of SWB and FWB decreased after the in vitro digestion. The reducing sugar released during the in vitro digestion from SWB and FWB decreased compared with their corresponding controls (SWC and FWC). FWB (IC₅₀ = 73.46 μg/mL) exhibited stronger α-Amylase inhibitory activity than SWB (IC₅₀ = 81.46 μg/mL). Different anthocyanins differed from binding affinities to bind with the active sites of α-Amylase via formation of hydrogen bonds. This study suggested whey protein encapsulated-blackcurrant concentrate might be an innovative food product with improved nutritional profiles. Both spray- and freeze-drying are potential options to this encapsulation.

Postprandial glucose-lowering effect of cagaita (Eugenia dysenterica DC) fruit juice in dysglycemic subjects with metabolic syndrome: An exploratory study

Cagaita (Eugenia dysenterica DC) is an ellagitannin-containing Myrtaceae fruit from Cerrado biome. This fruit seems to be a promising candidate for an adjuvant in glucose regulation in healthy subjects. However, it is not known whether cagaita juice would have the same effect on dysglycemic subjects with metabolic syndrome (MetS). Therefore, the present work aimed to evaluate the effect of cagaita fruit juice on postprandial glycemia in dysglycemic subjects with MetS, and whether cagaita ellagitannins could be metabolized to urolithins. To evaluate glycemic effects, two different meals were consumed by volunteers (n = 12) with a 1-week interval among them. The first one consisted of white bread (50 g) plus water (300 mL) as a control; the second one, white bread (50 g) plus clarified cagaita juice (300 mL). Bioavailability was assessed in 24 h urine, after the consumption of a single amount of 300 mL of cagaita juice by healthy (n = 16) and MetS subjects (n = 7). The results showed that dysglycemic subjects with MetS presented a 53% reduction of incremental area under the curve (iAUC) of glucose, 38% reduction of insulin, 78% reduction of GIP (glucose-dependent insulinotropic polypeptide), and 58% reduction of C-peptide (p < 0.05), after the consumption of cagaita juice along with bread, in comparison to control water. However, both GLP-1 (glucagon-like peptide-1) and glucagon were not affected by cagaita juice ingestion. Concerning bioavailability, it was observed, for the first time, the metabolization of cagaita ellagitannins to urolithins by healthy and dysglycemic individuals with MetS, with a prevalence of metabotype B in both groups (44% and 42%, respectively), followed by metabotype A (37% and 29%, respectively), and metabotype 0 (19% and 29%, respectively).

Effects of Anthocyanins in Composite Meals on Cardiometabolic Outcomes-A Systematic Review of Randomized Controlled Feeding Trials

Accumulating epidemiological evidence suggests that anthocyanin intake is associated with reduced risks of cardiometabolic disorders, highlighting the importance of incorporating the phytochemical in our diets. Numerous food-based intervention studies have examined, in controlled meal settings, the role of anthocyanin on cardiometabolic health; but their effects have not been systematically summarized. This study aims to systematically review and summarize the effects of anthocyanin consumption with composite meals on cardiometabolic health from randomized controlled feeding trials. A systematic literature search for relevant human nutritional intervention studies was performed using PubMed, Embase, Cochrane Library, CINAHL Plus with Full Text, and Scopus databases. The Cochrane Risk of Bias tool was used to assess the study quality. Eighteen articles involving 371 participants were included in this review. Consistent improvements from anthocyanin intake were found in glycemic, gastric inhibitory peptide (GIP), interleukin-6 (IL-6), and oxygen radical absorbance capacity (ORAC) responses. Anthocyanin intake did not significantly affect other markers of energy metabolism, vascular functions, oxidative stress and antioxidant status, as well as inflammatory responses. Inconsistencies in successful outcomes between epidemiological studies and included interventions were largely attributed to matrix effects, which may impede the bioaccessibility of anthocyanins and consequently, limiting its health benefits when co-delivered with some foods.

Targets and mechanisms of dietary anthocyanins to combat hyperglycemia and hyperuricemia: a comprehensive review

Hyperglycemia and hyperuricemia are both metabolic disorders related to excessive amount of metabolites in blood, which are considered as high risk factors for the development of many chronic diseases. Enzymes, cells, tissues and organs, which are relevant to metabolism and excretion of glucose and UA, are usually regarded to be the targets in treatment of hyperglycemia and hyperuricemia. Several drugs have been commonly applied to combat hyperglycemia and hyperuricemia through various targets but with unignorable side effects. Anthocyanins have become promising alternatives against hyperglycemia and hyperuricemia because of their bio-activities with little side effects. Structurally different anthocyanins from berry fruits, cherries and purple sweet potato lead to the diverse functional activity and property. This review is aimed to illustrate the specific targets that are available for anthocyanins from berry fruits, cherries and purple sweet potato in hyperglycemia and hyperuricemia management, as well as discuss the structure-activity relationship, and the underlying mechanisms associated with intracellular signaling pathway, anti-oxidative stress and anti-inflammation. In addition, the relationship of hyperglycemia and hyperuricemia, and the possibly regulative role of anthocyanins against them, along with the effects of anthocyanins in clinical trial are mentioned.

In Vivo Screening and Antidiabetic Potential of Polyphenol Extracts from Guava Pulp, Seeds and Leaves

Simple Summary

The incidence of diabetes has risen from 151 million people in 2000 to 463 million in 2019, with 4.2 million estimated deaths in 2019, and over 700 million people will be affected with diabetes worldwide by 2045. Thus, the screening of anti-diabetic plants is inevitable in order to overcome diabetes. This study has investigated the anti-diabetic potential of polyphenol extracts from guava leaves, seeds and pulp using an albino rat model. The in vivo study has reported that polyphenols from leaves and pulp have an ability to improve diabetic parameters, such as insulin, blood glucose and triglycerides levels. The improvement in blood parameters is also an indication of these extracts that are valuable for diabetes management. The findings of this study reveal that polyphenols from guava leaves, pulp and seeds can be used for drug development.

Abstract

The present study investigates the antidiabetic potential of polyphenol extracts purified from guava pulp, seeds and leaves using an in vivo experiment on albino rats. The polyphenols from guava pulp, seeds and leaves were extracted using methanol solvent and the sonication method while being evaluated by total phenolic contents and radical scavenging activity assay. The proximate composition of powders revealed that ash, protein and total sugars were significantly (p < 0.05) higher in leaves and seeds, while vitamin C was highest in pulp. Total phenolic and antioxidant activities were highest in pulp followed by leaves and seeds. The findings of feed intake and body gain revealed that the supplementation of polyphenols, especially from pulp, significantly (p < 0.05) increased the feed intake, which resulted in increased body weight. Moreover, total cholesterol (TC) and low-density lipoprotein (LDL) levels were significantly (p < 0.05) decreased, while the level of high-density lipoprotein (HDL) was increased in groups fed with polyphenols from guava pulp compared to both (+ive and –ive) control groups. Furthermore, blood glucose and triglycerides were significantly (p < 0.05) decreased in supplemented groups compared to the control group of diabetes mice, which resulted in the inhibition of α-amylase and glucose transport. Besides this, packed cell volume (PCV), mean corpuscular volume (MCV), hemoglobin, red blood cells (RBCs), white blood cells (WBCs) and platelet levels were increased significantly (p < 0.05) in pulp’s extract followed by leaves and seeds compared to both control groups. Overall, the antidiabetic potential of different extracts was in the following order: pulp > leaves > seeds. The findings suggest the feasibility of adding 200–250 mg/kg.bw of polyphenol extracts of pulp as an alternative to diabetic drugs.

Investigation of Ultrasonic Treatment on Physicochemical, Structural and Morphological Properties of Sodium Alginate/AgNPs/Apple Polyphenol Films and Its Preservation Effect on Strawberry

An antibacterial and anti-oxidation composite film was prepared by a casting method using sodium alginate (SA) and apple polyphenols (APPs) as the base material and glycerol as the plasticizer. Silver nanoparticles (AgNPs) were deposited by ultrasonic-assisted electrospray method. The degree of influence of the addition ratio of SA and AgNPs and different ultrasonic time on the mechanical properties, barrier properties, optical properties, and hydrophilicity of the composite film was explored. The composite films were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) and scanning electron microscopy (SEM). The results showed that the SA: AgNPs ratio of 7:3 and the ultrasonic time for 30 min have the best comprehensive performance, and SA/AgNPs/APP films showed the lowest water vapor permeability value of 0.75 × 10⁻¹¹ g/m·s·Pa. The composite film has good strength and softness, with tensile strength (TS) and elongation at break (E) at 23.94 MPa and 29.18%, respectively. SEM images showed that the surface of the composite film was smooth and the AgNPs’ distribution was uniform. The composite film showed broad antibacterial activity, and the antibacterial activity of Escherichia coli (92.01%) was higher than that of Staphylococcus aureus (91.26%). However, due to the addition of APP, its antioxidant activity can reach 98.39%, which has a synergistic effect on antibacterial activity. For strawberry as a model, the results showed that this composite film can prolong the shelf life of strawberries for about 8 days at 4 °C, effectively maintaining their storage quality. Compared with the commonly used PE(Polyethylene film) film on the market, it has a greater fresh-keeping effect and can be used as an active food packaging material.

Co-ingested vinegar-soaked or preloaded dried apple mitigated acute postprandial glycemia of rice meal in healthy subjects under equicarbohydrate conditions

This study investigated 2 possible approaches to dietary control of acute postprandial responses to a rice-based meal under equicarbohydrate conditions: (1) a dried apple (DA) preload and (2) co-ingestion of vinegar-soaked DA. We hypothesized that both approaches would counteract hyperglycemia with no negative effect on satiety, possibly explained by an inhibitory effect on digestive enzyme activity and/or the effect of the sugar component of the DA. Fifteen healthy female subjects consumed (1) rice, (2) co-ingestion of DA and rice (DA + R), (3) DA preload and rice (PDA + R), (4) rice with sugar solution (same sugar profile as in DA) preloaded (PSS + R), or (5) co-ingestion of rice with vinegar-soaked DA (VDA + R) in a randomized crossover trial. Acute postprandial glycemic response tests and subjective satiety tests were conducted for each test meal. Compared with rice reference, the PA + R and PSS + R achieved 31.4% and 36.3% reduction of the incremental area under the curve_0-120, 24.3% and 27.0% decreases in the average glucose peak, along with 21.6% and 27.0% decreases in glycemic excursion in 240 minutes, whereas the VDA + R resulted 42.4%, 27.0%, and 29.7% reductions in the incremental area under the curve_0-120, peak, and glycemic excursion, respectively. The DA-containing meals had no effect or a favorable effect on satiety. The in vitro assay found larger resistant starch and smaller rapid digestible starch fractions in DA + R and VDA + R meals compared to those of the rice reference (P < .001). The result of this study supported the research hypothesis, and the DA-containing meals could be considered as a potential dietary approach for glycemic management.

The Therapeutic Potential of Anthocyanins: Current Approaches Based on Their Molecular Mechanism of Action

Anthocyanins are natural phenolic pigments with biological activity. They are well-known to have potent antioxidant and antiinflammatory activity, which explains the various biological effects reported for these substances suggesting their antidiabetic and anticancer activities, and their role in cardiovascular and neuroprotective prevention. This review aims to comprehensively analyze different studies performed on this class of compounds, their bioavailability and their therapeutic potential. An in-depth look in preclinical, in vitro and in vivo, and clinical studies indicates the preventive effects of anthocyanins on cardioprotection, neuroprotection, antiobesity as well as their antidiabetes and anticancer effects.

Select Polyphenol-Rich Berry Consumption to Defer or Deter Diabetes and Diabetes-Related Complications

Berries are considered "promising functional fruits" due to their distinct and ubiquitous therapeutic contents of anthocyanins, proanthocyanidins, phenolic acids, flavonoids, flavanols, alkaloids, polysaccharides, hydroxycinnamic, ellagic acid derivatives, and organic acids. These polyphenols are part of berries and the human diet, and evidence suggests that their intake is associated with a reduced risk or the reversal of metabolic pathophysiologies related to diabetes, obesity, oxidative stress, inflammation, and hypertension. This work reviewed and summarized both clinical and non-clinical findings that the consumption of berries, berry extracts, purified compounds, juices, jams, jellies, and other berry byproducts aided in the prevention and or otherwise management of type 2 diabetes mellitus (T2DM) and related complications. The integration of berries and berries-derived byproducts into high-carbohydrate (HCD) and high-fat (HFD) diets, also reversed/reduced the HCD/HFD-induced alterations in glucose metabolism-related pathways, and markers of oxidative stress, inflammation, and lipid oxidation in healthy/obese/diabetic subjects. The berry polyphenols also modulate the intestinal microflora ecology by opposing the diabetic and obesity rendered symbolic reduction of Bacteroidetes/Firmicutes ratio, intestinal mucosal barrier dysfunction-restoring bacteria, short-chain fatty acids, and organic acid producing microflora. All studies proposed a number of potential mechanisms of action of respective berry bioactive compounds, although further mechanistic and molecular studies are warranted. The metabolic profiling of each berry is also included to provide up-to-date information regarding the potential anti-oxidative/antidiabetic constituents of each berry.

Apple polyphenol-rich drinks dose-dependently decrease early-phase postprandial glucose concentrations following a high-carbohydrate meal: a randomized controlled trial in healthy adults and in vitro studies

BACKGROUND

Previous research demonstrated that a high dose of phlorizin-rich apple extract (AE) can markedly inhibit early-phase postprandial glycemia, but efficacy of lower doses of the AE is unclear.

OBJECTIVE

To determine whether lower AE doses reduce early-phase postprandial glycemia in healthy adults and investigate mechanisms.

DESIGN

In a randomized, controlled, double-blinded, cross-over acute trial, drinks containing 1.8 g (HIGH), 1.35 g (MED), 0.9 g (LOW), or 0 g (CON) of a phlorizin-rich AE were consumed before 75 g starch/sucrose meal. Postprandial blood glucose, insulin, C-peptide, glucose-dependent insulinotropic polypeptide (GIP) and polyphenol metabolites concentrations were measured 0-240 min, acetaminophen concentrations to assess gastric emptying rate, and 24 h urinary glucose excretion. Effects of AE on intestinal glucose transport were investigated in Caco-2/TC7 cells.

RESULTS

AE significantly reduced plasma glucose iAUC 0-30 min at all doses: mean differences (95% CI) relative to CON were -15.6 (-23.3, -7.9), -11.3 (-19.6, -3.0) and -8.99 (-17.3, -0.7) mmol/L per minute for HIGH, MEDIUM and LOW respectively, delayed T_max (HIGH, MEDIUM and LOW 45 min vs. CON 30 min), but did not lower C_max. Similar dose-dependent treatment effects were observed for insulin, C-peptide, and GIP. Gastric emptying rates and urinary glucose excretion did not differ. Serum phloretin, quercetin and epicatechin metabolites were detected postprandially. A HIGH physiological AE dose equivalent decreased total glucose uptake by 48% in Caco-2/TC7 cells.

CONCLUSIONS

Phlorizin-rich AE, even at a low dose, can slightly delay early-phase glycemia without affecting peak and total glycemic response.

Short-term, but not acute, intake of New Zealand blackcurrant extract improves insulin sensitivity and free-living postprandial glucose excursions in individuals with overweight or obesity

Abstract

Impaired postprandial glucose handling and low-grade systemic inflammation are risk factors for developing insulin resistance in individuals with overweight or obesity. Acute ingestion of anthocyanins improves postprandial glucose responses to a single carbohydrate-rich meal under strictly controlled conditions.

Purpose

Examine whether acute and short-term supplementation with anthocyanin-rich New Zealand blackcurrant (NZBC) extract can improve postprandial glucose responses to mixed-macronutrient meals.

Methods

Twenty-five overweight (BMI > 25 kg m²) sedentary individuals participated in one of the following double-blinded, randomised controlled trials: (1) ingestion of 600 mg NZBC extract or placebo prior to consumption of a high-carbohydrate, high-fat liquid meal (n = 12); (2) 8-days supplementation with NZBC extract (600 mg day⁻¹) or placebo, with insulin sensitivity and markers of inflammation assessed on day-7, and free-living postprandial glucose (continuous glucose monitoring) assessed on day-8 (n = 13).

Results

A single dose of NZBC extract had no effect on 3 h postprandial glucose, insulin or triglyceride responses. However, in response to short-term NZBC extract supplementation insulin sensitivity was improved (+ 22%; P = 0.011), circulating C-reactive protein concentrations decreased (P = 0.008), and free-living postprandial glucose responses to both breakfast and lunch meals were reduced (− 9% and − 8%, respectively; P < 0.05), compared to placebo.

Conclusion

These novel results indicate that repeated intake, rather than a single dose of NZBC extract, is required to induce beneficial effects on insulin sensitivity and postprandial glucose handling in individuals with overweight or obesity. Continuous glucose monitoring enabled an effect of NZBC extract to be observed under free-living conditions and highlights the potential of anthocyanin-rich supplements as a viable strategy to reduce insulin resistance.

The effect of 8 plant extracts and combinations on post-prandial blood glucose and insulin responses in healthy adults: a randomized controlled trial

BACKGROUND

Lower post-prandial glucose (PPG) and insulin (PPI) responses to foods are associated with reduced diabetes risk and progression. Several plant extracts have been proposed to reduce PPG or PPI by inhibiting enzymes or transporters involved in carbohydrate digestion and uptake. This study evaluates a range of such extracts, consumed with a carbohydrate load, for their effects on PPG, PPI and indicators of (gastrointestinal) tolerance.

METHODS

Interventions were extracts of mulberry fruit (MFE, 1.5 g), mulberry leaf (MLE, 1.0 g), white bean (WBE, 3.0 g), apple (AE, 2.0 g), elderberry (EE, 2.0 g), turmeric (TE, 0.18 g), AE + TE, and EE + TE. Each of these 8 individual extracts or combinations were added to a rice porridge containing ~ 50 g available carbohydrate (control). In a within-subject (randomised, balanced incomplete block) design, individual subjects received the control and a subset of 4 of the 8 extracts or combinations. Participants were 72 apparently healthy adults (mean [SD] age 31.2 [5.5] yr, body mass index 22.1 [2.0] kg/m2). The primary outcome was the percentage change in 2-h PPG (positive incremental area under the curve) relative to control. Secondary measures were the 2-h PPI response, 7-h breath hydrogen, measures of gastrointestinal discomfort, and urine glucose.

RESULTS

In the 65 subjects who completed the control and at least one intervention treatment, additions of AE, MFE and MLE produced statistically significant reductions in PPG vs control (p < 0.05; mean effect - 24.1 to - 38.1%). All extracts and combinations except TE and WBE significantly reduced PPI (p < 0.01; mean effect - 17.3% to - 30.4%). Rises in breath hydrogen > 10 ppm were infrequent, but statistically more frequent than control only for MLE (p = 0.02). Scores for gastrointestinal discomfort were extremely low and not different from control for any treatment, and no glucosuria was observed.

CONCLUSIONS

Additions of AE, MFE and MLE to rice robustly reduced PPG and PPI. EE significantly reduced only PPI, while TE and WBE showed no significant efficacy for PPG or PPI. Breath hydrogen responses to MLE suggest possible carbohydrate malabsorption at the dose used, but there were no explicit indications of intolerance to any of the extracts.

TRIAL REGISTRATION

ClinicalTrials.gov identifier NCT04258501. Registered 6 February 2020 - Retrospectively registered.