Margherita Dall’Asta

Masked mycotoxins are efficiently hydrolyzed by human colonic microbiota releasing their aglycones.

Fusarium mycotoxins are secondary metabolites produced by Fusarium spp. in cereals. Among them, deoxynivalenol (DON) and zearalenone (ZEN) are widespread worldwide contaminants of cereal commodities and are ranked as the most important chronic dietary risk factors. Their conjugates, known as masked mycotoxins, have been described but are still not accounted for in risk assessment studies. This study demonstrates for the first time that DON and ZEN are effectively deconjugated by the human colonic microbiota, releasing their toxic aglycones and generating yet unidentified catabolites. For this reason, masked mycotoxins should be considered when evaluating population exposure.

Polyphenolic Composition of Hazelnut Skin

Skins from different hazelnut samples were characterized for total polyphenol content, total antioxidant capacity (TAC), and their content in specific polyphenolic compounds. The main polyphenolic subclass, identified and quantified by means of HPLC-MS/MS, comprised monomeric and oligomeric flavan-3-ols, which accounted for more than 95% of total polyphenols. Flavonols and dihydrochalcones were 3.5% while phenolic acids were less than 1% of the total identified phenolics. The TAC values of the skin samples ranged between 0.6 and 2.2 mol of reduced iron/kg of sample, which is about 3 times the TAC of whole walnuts, 7-8 times that of dark chocolate, 10 times that of espresso coffee, and 25 times that of blackberries. By describing the profile of polyphenols present in hazelnut skins, this study provides the basis to further investigate the potential health effects of hazelnut byproduct.

In Vitro Bioaccessibility of Phenolics and Vitamins from Durum Wheat Aleurone Fractions

Durum wheat aleurone, thanks to its nutrient-rich composition, might be of potential use as a functional ingredient in cereal-based foods provided nutrients can be made available for absorption. We evaluated the in vitro bioaccessibility of thiamine, niacin, and phenolic acids in different aleurone fractions obtained with an industrial processing aimed to obtain material of different composition and particle size. Results indicate that the main phenolic compounds and vitamins investigated have a higher bioaccessibility when present in the inner part of the aleurone layer compared to the outer part of aleurone or the unfractionated bran. Moreover, an ultramicronization treatment employed to reduce particle size does not further improve the bioaccessibility of these compounds. We conclude that aleurone fractions from durum wheat bran could represent a nutritionally relevant ingredient, bringing together a high fiber content and an excellent bioaccessibility of vitamins and phytochemicals generally associated with nutritional benefits.

Glycaemic index of some commercial gluten-free foods

AbstractPurpose Gluten-free products present major challenges for the food industry in terms of organoleptic, technological and nutritional characteristics. The absence of gluten has been shown to affect starch digestibility, thus increasing the postprandial glycaemic response. However, in recent years, gluten-free technologies have been improved, thus possibly modifying this quality parameter. We investigated the glycaemic index (GI) of 10 commercial foods aiming to update the GI values of the most common gluten-free products consumed in Italy.MethodsThe in vivo GI was evaluated for six bakery products and four types of pasta. The postprandial glucose response was obtained in two groups with 10 healthy volunteers each.ResultsThe overall GI values ranged from 37.5 for breakfast biscuits to 66.7 for puffed multigrain cake. Breads and pasta had GI values consistently lower than those previously reported in the literature.ConclusionThe present study showed that several commercial GF products exhibited low and medium GI values, not confirming the previous observations on the high GI of GF. However, considering the multiple formulations and processes for preparation of these products, further studies are recommended.

Effects of naringenin and its phase II metabolites on in vitro human macrophage gene expression.

Abstract Naringenin, together with its glycosidic forms, is a flavanone abundant in grapefruit and orange. It has been detected in human plasma, following citrus juice intake, at sub-µmolar concentrations, and its main phase II conjugated metabolites (naringenin-7-O-glucuronide and narigenin-4′-O-glucuronide) have been identified in urine. Recent evidence suggests a potential active anti-inflammatory role of flavonoids on macrophages, cells actively involved in atherogenesis. The aim of this study was to evaluate the effects of naringenin and its phase II metabolites on the expression of specific genes in differently activated macrophages at concentrations coherent with dietary exposure. Results suggest that phase II metabolites, as well as the aglyconic form of naringenin, were able to perturb macrophage gene expression in directions that are not always consistent with anti-inflammatory effects. Moreover, the effects of metabolites were not always consistent with each other and with those of their aglycone, underlining the paramount importance of testing physiological forms of phytochemicals within in vitro experimental models. In vivo studies are needed to further explore these observations and investigate their practical consequences.

In Vitro Bioaccessibility of Phenolic Acids from a Commercial Aleurone-Enriched Bread Compared to a Whole Grain Bread

Wheat aleurone, due to its potentially higher bioaccessibility and bioavailability of micronutrients and phenolic acids, could represent a useful ingredient in the production of commonly consumed cereal-based food. The aim of the present study was to investigate the in vitro bioaccessibility of phenolic acids both from an aleurone-enriched bread and from a whole grain bread. The two bread samples were firstly characterized for the phenolic acid content. An in vitro digestion was then performed in order to evaluate the release of phenolic acids. The results obtained suggest that the bioaccessibility of the phenolic acids in the aleurone-enriched bread is higher than in the whole grain bread. These in vitro results suggest the potential use of aleurone in the production of foods, and this may represent an attractive possibility to vehicle nutritionally interesting components to consumers.

Hydrolysed fumonisin B1 and N-(deoxy-D-fructos-1-yl)-fumonisin B1: stability and catabolic fate under simulated human gastrointestinal conditions

Abstract Food processing may induce thermal degradation of fumonisins in corn via Maillard-type reactions, or alkaline hydrolysis via loss of the two tricarballylic acid moieties. In the former case, N-(1-deoxy-D-fructos-1-yl)-fumonisin B1 (NDF) can be formed, while the latter derivative is called hydrolysed fumonisin B1 (HFB1). The aim of this study was to deepen the knowledge about the gastrointestinal stability of HFB1 and NDF in humans. Due to the lack of standard, NDF was chemically synthesised and cleaned up in high purity to be used for further experiments. While NDF is already partially cleaved (about 41%) during simulated digestion, it remained rather stable towards human colon microflora. In contrast to this, HFB1 is partially metabolised by the colon microflora to unknown compounds after 24 h of fermentation, as seen by a loss of about 22%. Concluding, the cleavage of NDF during digestion as well as the likely metabolisation of HFB1 emphasise the need for animal trials to ascertain their toxicity in vivo.

A Systematic Review and Meta-Analysis of the Effects of Flavanol-Containing Tea, Cocoa and Apple Products on Body Composition and Blood Lipids: Exploring the Factors Responsible for Variability in Their Efficacy

Several randomized controlled trials (RCTs) and meta-analyses support the benefits of flavanols on cardiometabolic health, but the factors affecting variability in the responses to these compounds have not been properly assessed. The objectives of this meta-analysis were to systematically collect the RCTs-based-evidence of the effects of flavanol-containing tea, cocoa and apple products on selected biomarkers of cardiometabolic risk and to explore the influence of various factors on the variability in the responses to the consumption of these products. A total of 120 RCTs were selected. Despite a high heterogeneity, the intake of the flavanol-containing products was associated using a random model with changes (reported as standardized difference in means (SDM)) in body mass index (−0.15, p < 0.001), waist circumference (−0.29, p < 0.001), total-cholesterol (−0.21, p < 0.001), LDL-cholesterol (−0.23, p < 0.001), and triacylglycerides (−0.11, p = 0.027), and with an increase of HDL-cholesterol (0.15, p = 0.005). Through subgroup analyses, we showed the influence of baseline-BMI, sex, source/form of administration, medication and country of investigation on some of the outcome measures and suggest that flavanols may be more effective in specific subgroups such as those with a BMI ≥ 25.0 kg/m2, non-medicated individuals or by specifically using tea products. This meta-analysis provides the first robust evidence of the effects induced by the consumption of flavanol-containing tea, cocoa and apple products on weight and lipid biomarkers and shows the influence of various factors that can affect their bioefficacy in humans. Of note, some of these effects are quantitatively comparable to those produced by drugs, life-style changes or other natural products. Further, RCTs in well-characterized populations are required to fully comprehend the factors affecting inter-individual responses to flavanol and thereby improve flavanols efficacy in the prevention of cardiometabolic disorders.

Protection of pancreatic β-cell function by dietary polyphenols

Abstract Diabetes mellitus is a complex metabolic disorder and is considered a fast-growing global health problem. Type 2 diabetes (T2D) represents the majority of total diabetes prevalence and β-cell dysfunction has been described as a crucial point for this disease development and progression. To date, all of the common anti-hyperglycaemic drugs used for diabetes management cause undesirable side effects or problems with long-term efficacy or safety and the development of alternative approaches for the prevention as well as for the treatment of T2D might be a valuable solution to meet this rising demand. In this regards, numerous epidemiological studies indicate that exposure to certain polyphenol compounds is associated with the prevention of chronic diseases, including diabetes. Here, we review growing evidence suggesting that polyphenols can modulate the activity of various molecular targets, which are known to control β-cell function, involved in the development and the progression of this diabetes. The protective effects of polyphenols on β-cell function is reported with a particular focus on the mechanism of action behind polyphenol putative bioactivity. Animal and in vitro studies selected in this review, reporting about both flavonoid and non-flavonoid compounds, highlight the direct action of polyphenols on pancreatic β-cells, stimulating insulin secretion through the activation of specific cellular targets and protecting these cells from damages mediated by oxidative stress and inflammation, both typically elevated in diabetes. Some of the reviewed studies describe polyphenol effects comparable to those exerted by many drugs commonly used in diabetes treatment, and, in some occasions, synergistic polyphenol-drug interactions. Finally, future studies need to be addressed to the effects of specific polyphenol human and microbial metabolites, which are still poorly studied, in order to better define the preventive and therapeutic approach to contrast β-cell failure and diabetes progression.

Gastrointestinal stability of urolithins: an in vitro approach

PurposeUrolithins are bioactive ellagitannin-derived metabolites showing a wide phenotypic variation in their production by the gut microbiota. This work represents a first in vitro step toward the development of new strategies focused on the oral supplementation of urolithins with the aim of overcoming their selective production and making their putative health benefits available for the whole population.MethodsIn order to study their gastrointestinal stability, urolithin A, urolithin B, and urolithin B-glucuronide, as well as ellagic acid, were subjected to a simulated gastrointestinal digestion model consisting of oral, gastric, and pancreatic steps followed by a 24-h fecal fermentation. The effect of the entero-hepatic recirculation on urolithin B-glucuronide, a phase II metabolite, was also investigated.ResultsUrolithin B was the molecule able to resist to a greater extent the conditions of the gastrointestinal tract, while urolithin A and ellagic acid were drastically unstable during the colonic step. Conjugation with glucuronic acid, ideally occurring in the liver, conferred to urolithin B an increased stability, which may be interesting in the framework of entero-hepatic recirculation.ConclusionThis set of experiments lets hypothesize that orally supplemented urolithins may come into contact with the colonic epithelium and become accessible for uptake or exert local anti-inflammatory activity, overcoming the limitations of enterotypes unable to convert ellagitannins into these putatively beneficial metabolites.