The effects of wild blueberry consumption on plasma markers and gene expression related to glucose metabolism in the obese Zucker rat

A One-Week Elderberry Juice Intervention Augments the Fecal Microbiota and Suggests Improvement in Glucose Tolerance and Fat Oxidation in a Randomized Controlled Trial

Obesity is a costly and ongoing health complication in the United States and globally. Bioactive-rich foods, especially those providing polyphenols, represent an emerging and attractive strategy to address this issue. Berry-derived anthocyanins and their metabolites are of particular interest for their bioactive effects, including weight maintenance and protection from metabolic aberrations. Earlier findings from small clinical trials suggest modulation of substrate oxidation and glucose tolerance with mediation of prospective benefits attributable to the gut microbiota, but mixed results suggest appropriate anthocyanin dosing poses a challenge. The objective of this randomized, placebo-controlled study was to determine if anthocyanin-dense elderberry juice (EBJ) reproduces glucoregulatory and substrate oxidation effects observed with other berries and if this is mediated by the gut microbiota. Overweight or obese adults (BMI > 25 kg/m2) without chronic illnesses were randomized to a 5-week crossover study protocol with two 1-week periods of twice-daily EBJ or placebo (PL) separated by a washout period. Each treatment period included 4 days of controlled feeding with a 40% fat diet to allow for comparison of measurements in fecal microbiota, meal tolerance testing (MTT), and indirect calorimetry between test beverages. Eighteen study volunteers completed the study. At the phylum level, EBJ significantly increased Firmicutes and Actinobacteria, and decreased Bacteroidetes. At the genus level, EBJ increased Faecalibacterium, Ruminococcaceae, and Bifidobacterium and decreased Bacteroides and lactic acid-producing bacteria, indicating a positive response to EBJ. Supporting the changes to the microbiota, the EBJ treatment significantly reduced blood glucose following the MTT. Fat oxidation also increased significantly both during the MTT and 30 min of moderate physical activity with the EBJ treatment. Our findings confirm the bioactivity of EBJ-sourced anthocyanins on outcomes related to gut health and obesity. Follow-up investigation is needed to confirm our findings and to test for longer durations.

Blueberry (Vaccinium spp.) Anthocyanins and Their Functions, Stability, Bioavailability, and Applications

Blueberry fruits are rich in anthocyanins. There are 25 known anthocyanidins found in blueberries (Vaccinium spp.) until now. Anthocyanins found in blueberries have attracted considerable interest for their outstanding abilities as antioxidants, anti-inflammatory agents, anti-diabetic, anti-obesity, and neuroprotection compounds, as well as their potential for preventing cardiovascular diseases, protecting vision, and inhibiting cancer development. However, their application is constrained by issues related to instability and relatively low bioavailability. Thus, this review provides a detailed overview of categories, functions, stability, and bioavailability of blueberry anthocyanins and their practical applications. The available studies indicate that there is more potential for the industrial production of blueberry anthocyanins.

Cornelian Cherry (Cornus mas L.) Fruit Extract Lowers SREBP-1c and C/EBPα in Liver and Alters Various PPAR-α, PPAR-γ, LXR-α Target Genes in Cholesterol-Rich Diet Rabbit Model

Cornelian cherry (Cornus mas L.) fruits, abundant in iridoids and anthocyanins, are natural products with proven beneficial impacts on the functions of the cardiovascular system and the liver. This study aims to assess and compare whether and to what extent two different doses of resin-purified cornelian cherry extract (10 mg/kg b.w. or 50 mg/kg b.w.) applied in a cholesterol-rich diet rabbit model affect the levels of sterol regulatory element-binding protein 1c (SREBP-1c) and CCAAT/enhancer binding protein α (C/EBPα), and various liver X receptor-α (LXR-α), peroxisome proliferator-activated receptor-α (PPAR-α), and peroxisome proliferator-activated receptor-γ (PPAR-γ) target genes. Moreover, the aim is to evaluate the resistive index (RI) of common carotid arteries (CCAs) and aortas, and histopathological changes in CCAs. For this purpose, the levels of SREBP-1c, C/EBPα, ATP-binding cassette transporter A1 (ABCA1), ATP-binding cassette transporter G1 (ABCG1), fatty acid synthase (FAS), endothelial lipase (LIPG), carnitine palmitoyltransferase 1A (CPT1A), and adiponectin receptor 2 (AdipoR2) in liver tissue were measured. Also, the levels of lipoprotein lipase (LPL), visceral adipose tissue-derived serine protease inhibitor (Vaspin), and retinol-binding protein 4 (RBP4) in visceral adipose tissue were measured. The RI of CCAs and aortas, and histopathological changes in CCAs, were indicated. The oral administration of the cornelian cherry extract decreased the SREBP-1c and C/EBPα in both doses. The dose of 10 mg/kg b.w. increased ABCA1 and decreased FAS, CPT1A, and RBP4, and the dose of 50 mg/kg b.w. enhanced ABCG1 and AdipoR2. Mitigations in atheromatous changes in rabbits' CCAs were also observed. The obtained outcomes were compared to the results of our previous works. The beneficial results confirm that cornelian cherry fruit extract may constitute a potentially effective product in the prevention and treatment of obesity-related disorders.

Wild blueberry (V. angustifolium) improves TNFα-induced cell barrier permeability through claudin-1 and oxidative stress modulation in Caco-2 cells

Increasing evidence links the impairment of intestinal permeability (IP), a feature of the intestinal barrier, to numerous dysmetabolic and dysfunctional conditions. Several host and environmental factors, including dietary factors, can negatively and/or positively affect IP. In this regard, polyphenol-rich foods including berries have been proposed as potential IP modulators. However, the exact mechanisms involved are not yet fully elucidated. The aim of the present study was to evaluate the effect of a wild blueberry (WB; V. angustifolium) powder, naturally rich in polyphenols, to affect Caco-2 cell monolayer permeability and to identify the potential mechanisms in modulating the IP process. Caco-2 cells were incubated with TNF-α (10 ng mL-1), as a pro-inflammatory stimulus, and supplemented for 24 hours with different concentrations (1 and 5 mg mL-1) of WB powder. The integrity of the intestinal cell monolayer was evaluated by measuring the transepithelial electrical resistance (TEER) and the paracellular transport of FITC-dextran. In addition, the production of the tight junction proteins, such as claudin-1 and occludin, as well as protein carbonyl and 8-hydroxy 2 deoxyguanosine, as oxidative stress markers, were quantified in the supernatant by ELISA kits. Overall, the treatment with WB powder (5 mg mL-1) mitigated the loss of Caco-2 cell barrier integrity, as documented by an increase in TEER and a reduction in FITC values. This modulation was accompanied by an upregulation of claudin-1 and a reduction of 8-OHdG. Conversely, no effect was documented for the lower concentration (1 mg mL-1) and the other IP markers, as well as oxidative stress markers analysed. In conclusion, our findings suggest a potential role of WB in the modulation of cell barrier integrity. This modulation process could be attributed to an increase in claudin-1 expression and a reduction in 8-OHdG. Further studies should be performed to corroborate the results obtained. In addition, since the effects were observed at doses of WB achievable with the diet, these findings should be substantiated also through in vivo approaches.

Vaccinium as Potential Therapy for Diabetes and Microvascular Complications

Diabetes mellitus is one of the most critical global health concerns, with a fast-growing prevalence. The incidence of diabetic vascular complications is also rapidly increasing, exacerbating the burden on individuals with diabetes and the consumption of public medical resources. Despite the overall improvements in the prevention, diagnosis, and treatment of diabetic microvascular complications in recent years, safe and effective alternative or adjunctive therapies are urgently needed. The mechanisms underlying diabetic vascular complications are complex, with hyperglycemia-induced oxidative stress and inflammation being the leading causes. Therefore, glycemic control, antioxidation, and anti-inflammation are considered the main targets for the treatment of diabetes and its vascular comorbidities. Vaccinium L. (Ericaceae) is a genus of plants enriched with polyphenolic compounds in their leaves and fruits. Vaccinium and its extracts have demonstrated good bioactivity in reducing blood glucose, oxidative stress, and inflammation, making them excellent candidates for the management of diabetes and diabetic vascular complications. Here, we review recent preclinical and clinical studies on the potential effect of Vaccinium on ameliorating diabetes and diabetic complications, particularly diabetic kidney disease and diabetic retinopathy.

Blueberry Consumption and Changes in Obesity and Diabetes Mellitus Outcomes: A Systematic Review

Low-grade inflammation and oxidative stress are key mechanisms involved in obesity and related disorders. Polyphenols from blueberry (BB) and bilberries (BiB) might protect against oxidative damage and inflammation. To summarize the effects of BiB or BB consumption in parameters related to obesity and its comorbidities, a search of the literature was performed in PubMed, Embase, and Cochrane Library repositories to identify all studies that evaluated associations of whole BB or BiB with obesity and associated disorders. Thirty-one studies were eligible for inclusion in this review: eight clinical trials and 23 animal studies. In humans, BB consumption only consistently decreased oxidative stress and improved endothelial function. In rodents, BB or BiB consumption caused positive effects on glucose tolerance, nuclear factor-kappa B (Nf-κb) activity, oxidative stress, and triglyceride (TG) content in the liver and hepatic steatosis. The high content of anthocyanins present in BB and BiB seems to attenuate oxidative stress. The decrease in oxidative stress may have a positive impact on glucose tolerance and endothelial function. Moreover, in rodents, these berries seem to protect against hepatic steatosis, through the decreased accumulation of hepatic TGs. BB and BiB might also attenuate inflammation by decreasing Nf-κb activity and immune cell recruitment into the adipose tissue.

Blueberry as an Attractive Functional Fruit to Prevent (Pre)Diabetes Progression

Prediabetes, a subclinical impairment between euglycemia and hyperglycemia, is a risk factor for the development of type 2 diabetes mellitus (T2DM) and associated micro- and macrovascular complications. Lifestyle therapy, the first-line treatment of prediabetes, includes physical exercise and dietary regimens enriched in phytochemicals with health-related properties. Blueberries (Vaccinium spp.), given their pleasant taste and great abundance in beneficial phytochemicals, have gained public interest all over the world. Along with a high antioxidant activity, this functional fruit is also well-recognized due to its hypoglycemic and insulin-sensitizing effects and has been recommended for overt T2DM management. Yet blueberries target several other pathophysiological traits, namely gut microbiota dysbiosis and hepatic dysmetabolism, that ensue when prediabetes begins and for which pharmacological interventions tend to be delayed. In this work, we revisited preclinical data from in vitro assays, animal models and human studies, aiming to disclose the potential mechanisms by which blueberries may be a fruitful source of phytochemicals able to prevent (pre)diabetes progression. Collectively, future efforts should focus on longer-term studies with standardized interventions and readouts, particularly in humans, that will hopefully bring more robust evidence and concrete guidance for blueberries' effective use in prediabetes.

Blueberry intervention improves metabolic syndrome risk factors: systematic review and meta-analysis

Recent studies have found that blueberry supplementation can improve parameters related to metabolic syndrome (MetS); however, there is no definitive consensus. Analysis of several randomized controlled trials can demonstrate whether a reduced effect of MetS risk factors is more pronounced in individuals who received supplementation with blueberry than in individuals who did not receive this supplementation. This systematic review and meta-analysis aimed to investigate the effect of blueberry intervention on MetS risk factors, including blood pressure, anthropometric measurements, and glycemic and lipid profiles. PubMed, Scopus, Web of Science, and SciELO were systematically searched to identify relevant studies published before July 2020. To compare the effects of blueberry supplements (powder, extract, fruit, juice, or frozen) with placebo, the mean differences with 95 % confidence intervals (CI) were pooled based on the random-effects model. We classified the quality of evidence according to the GRADE approach. In total, 18 randomized controlled trials (RCTs) were included in this systematic review, and 12 studies were selected for meta-analysis. Based on the Cochrane Collaboration risk-of-bias tool, all studies were of good quality. These trials differed with regards to blueberry dosage and forms, recruited subjects, and trial duration. Meta-analyses of the data showed that blueberry intervention had a significant effect on lipid levels, decreasing total cholesterol and low-density lipoprotein (LDL) levels. We found no significant differences in the glycemic status markers and anthropometric measurements. Blueberry supplementation significantly decreased diastolic blood pressure. In conclusion, the meta-analysis showed that blueberry may be efficacious in the treatment of MetS, due to its beneficial effects on lipid and blood pressure markers.

Anthocyanin Bioactivity in Obesity and Diabetes: The Essential Role of Glucose Transporters in the Gut and Periphery

Obesity and type-2 diabetes trends continue to worsen in the United States. Dietary anthocyanins (typically provided by berries and other fruits) are reported to have protective effects against both conditions using a variety of experimental research models including animal and human feeding studies. This review highlights studies that explore the biochemical pathways in both tissue and rodent models which could explain clinical improvements noted with anthocyanin consumption. First, the primary mode of intestinal absorption of anthocyanins is through both sGLT1 and GLUT2 glucose transporters. Stronger binding affinities may allow anthocyanins to be more inhibitive to glucose absorption compared to the reverse, where GLUT2 expression may also be affected. Genetic or chemical inhibition of sGLT1 or GLUT2 demonstrate their essential function in anthocyanin absorption across the enterocyte, where the former interacts with a greater variety of anthocyanins but the latter is the major transporter for specific anthocyanin-glycosides. Once absorbed, anthocyanins positively modulate GLUT4 density and function in both skeletal muscle and adipose tissues via the upregulation of AMPK and restoration of insulin sensitivity. Antioxidant properties and phosphodiesterase inhibition by anthocyanins promote both mitochondrial function and density which could be novel targets for dietary management of obesity and its complications.

Recent Research on the Health Benefits of Blueberries and Their Anthocyanins

Awareness of the human health benefits of blueberries is underpinned by a growing body of positive scientific evidence from human observational and clinical research, plus mechanistic research using animal and in vitro models. Blueberries contain a large number of phytochemicals, including abundant anthocyanin pigments. Of their various phytochemicals, anthocyanins probably make the greatest impact on blueberry health functionality. Epidemiological studies associate regular, moderate intake of blueberries and/or anthocyanins with reduced risk of cardiovascular disease, death, and type 2 diabetes, and with improved weight maintenance and neuroprotection. These findings are supported by biomarker-based evidence from human clinical studies. Among the more important healthful aspects of blueberries are their anti-inflammatory and antioxidant actions and their beneficial effects on vascular and glucoregulatory function. Blueberry phytochemicals may affect gastrointestinal microflora and contribute to host health. These aspects have implications in degenerative diseases and conditions as well as the aging process. More evidence, and particularly human clinical evidence, is needed to better understand the potential for anthocyanin-rich blueberries to benefit public health. However, it is widely agreed that the regular consumption of tasty, ripe blueberries can be unconditionally recommended.

A Review of Biologically Active Natural Products from Mediterranean Wild Edible Plants: Benefits in the Treatment of Obesity and Its Related Disorders

Wild foods constitute an essential component of people’s diets around the world. According to the Food and Agriculture Organization (FAO), over 100 million people in the EU consume wild foods, while 65 million collect some form of wild food themselves. The Mediterranean basin is a biodiversity hotspot of wild edible species. Nowadays, due to the renewed interest in alimurgic plants and the recent findings on the beneficial role of their phytochemical constituents, these species have been defined as “new functional foods”. Research on natural products has recently regained importance with the growing understanding of their biological significance. Botanical food supplements marketed for weight and fat loss in obese subjects will be one of the most important items in marketed nutraceuticals. The aim of this report was to review the phytochemical compounds of Mediterranean wild edible species and their therapeutic potential against obesity and its related disorders. Results on the in vitro and in vivo activity of the most interesting plant extracts and their bioactive components are presented and discussed. The most interesting discoveries on their mechanisms of action are reported as well. Overall, this contribution highlights the importance and beneficial health roles of wild edible species.

Health promoting properties of blueberries: a review

With the strengthening of the link between diet and health, several foodstuffs have emerged as possessing potential health benefits such as phenolic rich fruits and vegetables. Blueberries, along with other berries, given their flavonoid and antioxidant content have long since been considered as a particularly interesting health promoting fruit. Therefore, the present work aimed to compile the existing evidences regarding the various potential benefits of blueberry and blueberry based products consumption, giving particular relevance to in vivo works and epidemiological studies whenever available. Overall, the results demonstrate that, while the evidences that support a beneficial role of blueberry and blueberry extracts consumption, further human based studies are still needed.

Molecular Mechanism and Health Role of Functional Ingredients in Blueberry for Chronic Disease in Human Beings

Functional ingredients in blueberry have the best health benefits. To obtain a better understanding of the health role of blueberry in chronic disease, we conducted systematic preventive strategies for functional ingredients in blueberry, based on comprehensive databases, especially PubMed, ISI Web of Science, and CNKI for the period 2008⁻2018. Blueberry is rich in flavonoids (mainly anthocyanidins), polyphenols (procyanidin), phenolic acids, pyruvic acid, chlorogenic acid, and others, which have anticancer, anti-obesity, prevent degenerative diseases, anti-inflammation, protective properties for vision and liver, prevent heart diseases, antidiabetes, improve brain function, protective lung properties, strong bones, enhance immunity, prevent cardiovascular diseases, and improve cognitive decline. The anthocyanins and polyphenols in blueberry are major functional ingredients for preventive chronic disease. These results support findings that blueberry may be one of the best functional fruits, and further reveals the mechanisms of anthocyanins and polyphenols in the health role of blueberry for chronic disease. This paper may be used as scientific evidence for developing functional foods, nutraceuticals, and novel drugs of blueberry for preventive chronic diseases.

Prevention of Atherosclerosis by Berries: The Case of Blueberries

Berry consumption has been associated with cardiovascular disease prevention in recent years. Atherosclerosis is one of the major causes of cardiovascular diseases. However, research on the prevention of atherosclerosis through consuming individual whole berries, specifically direct evidence, remains scarce. Therefore, further elucidating the role that berries play in the prevention of atherosclerosis is warranted. In this perspective, blueberries were selected to articulate research strategies for studying atheroprotective effects of berries. Studies from human subjects and various animal models are summarized. The mechanisms by which blueberries may act, through reducing oxidative stress, decreasing inflammation, improving endothelial dysfunction, regulating cholesterol accumulation and trafficking, along with potentially influencing gut microbiota, are also discussed. Blueberries contain high levels of polyphenolic compounds, which were widely indicated as major bioactive compounds. Nonetheless, the metabolites/catabolites after blueberry consumption, such as simple phenolic acids, rather than original compounds in berries, may be the actual in vivo bioactive compounds. Future research should focus on obtaining more direct evidence, preferably in humans, understanding of the mechanisms of action at the molecular level, and identifying bioactive compounds as well as which compounds act synergistically to convey health benefits. The research strategy discussed here may also be applied to the studies of other fruits and berries.

Effects of blueberry and cranberry consumption on type 2 diabetes glycemic control: A systematic review

The metabolic effects of cranberry and blueberry consumption on glycemic control have been evaluated in vitro and in animal models as well as in human studies, although findings have not been systematically reviewed yet. Therefore, a systematic review was carried out of relevant randomized clinical trials (RCTs) in order to assess the effect of berries (blueberry and cranberry) consumption on type 2 diabetes (T2DM) glycemic control. Some evidences were also discussed on the anti-diabetic mechanisms exerted by berries polyphenols. Studies were identified by searching electronic databases: LILACS, PubMed/MEDLINE, Scopus, The Cochrane Library and Web of Science. Three authors independently searched and extracted RCTs in which the effect of berries (cranberry or blueberry) consumption on T2DM glycemic control was assessed. A total of 7 RCTs, involving 270 adults with type 2 diabetes were included. Despite the heterogeneity of the administration forms (in natura, dried, extract, preparations - juice), dosage, duration of the intervention and type of population of the studies involving these two berries some studies highlight the potential benefit of berries, especially of blueberry, on glucose metabolism in T2DM subjects. Daily cranberry juice (240 mL) consumption for 12 weeks and blueberry extract or powder supplementation (9.1 to 9.8 mg of anthocyanins, respectively) for 8 to 12 weeks showed a beneficial effect on glucose control in T2DM subjects. Those results indicate a promising use of these berries in T2DM management; although more studies are required to better understand the mechanisms involved.

Dietary Anthocyanins and Insulin Resistance: When Food Becomes a Medicine

Insulin resistance is an abnormal physiological state that occurs when insulin from pancreatic β-cells is unable to trigger a signal transduction pathway in target organs such as the liver, muscles and adipose tissues. The loss of insulin sensitivity is generally associated with persistent hyperglycemia (diabetes), hyperinsulinemia, fatty acids and/or lipid dysregulation which are often prevalent under obesity conditions. Hence, insulin sensitizers are one class of drugs currently employed to treat diabetes and associated metabolic disorders. A number of natural products that act through multiple mechanisms have also been identified to enhance insulin sensitivity in target organs. One group of such compounds that gained interest in recent years are the dietary anthocyanins. Data from their in vitro, in vivo and clinical studies are scrutinized in this communication to show their potential health benefit through ameliorating insulin resistance. Specific mechanism of action ranging from targeting specific signal transduction receptors/enzymes to the general antioxidant and anti-inflammatory mechanisms of insulin resistance are presented.

Antiobesity Effects of Anthocyanins in Preclinical and Clinical Studies

The natural phytochemicals present in foods, including anthocyanins, might play a role in attenuating obesity by producing a decrease in weight and adipose tissue. This review focused on current knowledge about anthocyanins' role in obesity and its related comorbidities reported in animal models and humans. We summarized their target identification and mechanism of action through several pathways and their final effects on health and well-being. Into consideration of ongoing researches, we highlighted the following key points: a healthy relationship between anthocyanin supplementation and antiobesity effects suffers of the same pros and cons evidenced when the beneficial responses to other phytochemical treatments towards different degenerative diseases have been considered; the different dosage applied in animal versus clinical studies; the complex metabolism and biotransformation to which anthocyanins and phytochemicals are subjected in the intestine and tissues; the possibility that different components present in the supplemented mixtures can interact generating antagonistic, synergistic, or additive effects difficult to predict, and the difference between prevention and therapy. The evolution of the field must seriously consider the need to establish new and adequate cellular and animal models which may, in turn, allow the design of more efficient and prevention-targeted clinical studies.

Freeze-dried strawberry and blueberry attenuates diet-induced obesity and insulin resistance in rats by inhibiting adipogenesis and lipogenesis

Freeze-dried strawberry/blueberry powder might be useful for treatment/prevention of obesity-related diseases as it improves weight, fat and glucose-related biomarkers.

Blueberries' Impact on Insulin Resistance and Glucose Intolerance

Blueberries are a rich source of polyphenols, which include anthocyanin bioactive compounds. Epidemiological evidence indicates that incorporating blueberries into the diet may lower the risk of developing type 2 diabetes (T2DM). These findings are supported by pre-clinical and clinical studies that have shown improvements in insulin resistance (i.e., increased insulin sensitivity) after obese and insulin-resistant rodents or humans consumed blueberries. Insulin resistance was assessed by homeostatic model assessment-estimated insulin resistance (HOMA-IR), insulin tolerance tests, and hyperinsulinemic-euglycemic clamps. Additionally, the improvements in glucose tolerance after blueberry consumption were assessed by glucose tolerance tests. However, firm conclusions regarding the anti-diabetic effect of blueberries cannot be drawn due to the small number of existing clinical studies. Although the current evidence is promising, more long-term, randomized, and placebo-controlled trials are needed to establish the role of blueberries in preventing or delaying T2DM.

Recent Progress in Anti-Obesity and Anti-Diabetes Effect of Berries

Berries are rich in polyphenols such as anthocyanins. Various favorable functions of berries cannot be explained by their anti-oxidant properties, and thus, berries are now receiving great interest as food ingredients with “beyond antioxidant” functions. In this review, we discuss the potential health benefits of anthocyanin-rich berries, with a focus on prevention and treatment of obesity and diabetes. To better understand the physiological functionality of berries, the exact molecular mechanism of their anti-obesity and anti-diabetes effect should be clarified. Additionally, the relationship of metabolites and degradation products with health benefits derived from anthocyanins needs to be elucidated. The preventive effects of berries and anthocyanin-containing foods on the metabolic syndrome are not always supported by findings of interventional studies in humans, and thus further studies are necessary. Use of standardized diets and conditions by all research groups may address this problem. Berries are tasty foods that are easy to consume, and thus, investigating their health benefits is critical for health promotion and disease prevention.