Aflatoxin contamination in nuts marketed in Italy: preliminary results.
BACKGROUND: Aflatoxins (AFs) are one of the main groups of mycotoxins produced by molds. Nuts, although recognized as a food with health benefits, are frequently contaminated by AFs. STUDY DESIGN:
In this preliminary study we evaluated the contamination by total AFs and AFB1 in different types of nuts from different countries marketed in Apulia. METHODS: Overall, 124 samples (almonds, apricot kernels, chestnuts, hazelnuts, peanuts, pistachios, walnuts and Brazil nut) were analyzed using an High-Performance Liquid Chromatography system. RESULTS: Twenty samples (16.1%) were contaminated with AFs of which 55% were non-compliant, according to Reg. 165/2010. The median values (µg/kg) of total AFs and AFB1 were 16.6 and 15.1, respectively. Pistachios appeared more susceptible to AF contamination than the other nuts, with levels of total AFs ranging from 8.8 to 387.3 µg/kg and of AFB1 from 8.2 to 354.5 µg/kg. The majority of contaminated samples came from Asia and AF contamination was different in the various Asiatic sub-regions: regardless of the type of nuts, samples from Western Asia were the least contaminated. CONCLUSIONS: As geographical origin may influence the risk of contamination, in order to protect human health, customer countries should increase AF monitoring in nuts coming from those countries with favorable environments for the growth of aflatoxigenic molds or with less strict regulations.
Quantitative Risk Reduction Through Peanut Immunotherapy: Safety Benefits of an Increased Threshold in Europe.
BACKGROUND: The clinical relevance of increasing an allergic individual's peanut sensitivity threshold by immunotherapy, i.e., eliciting dose (ED) to 300 or 1000 mg peanut protein, has not been previously characterized in a European population. In this study, we quantify the clinical benefits of an increased threshold of reaction following immunotherapy for the peanut-allergic individual. METHODS: Quantitative risk assessments incorporated numerous inputs to predict the risk of an allergic reaction after exposure to residual peanut protein in packaged foods. The three primary inputs for the risk assessment were the peanut-allergic individual's clinical threshold value, the amount of food consumed per eating occasion of selected packaged foods and the concentration of peanut protein in the consumed product. Individual risk reductions were calculated for both children and adolescents-adults. RESULTS: Using available consumption and packaged food contamination data, children reaching an ED of 300 mg (if initial ED ≤ 100 mg) or 1,000 mg (if initial ED 300 mg) achieved >99.99% risk reduction. Adolescents-adults also achieved >99.99% risk reduction in all cases but one. Adolescents-adults who reached an ED of 300 mg (if initial ED ≤ 100 mg) achieved 99.3-99.9% risk reduction when consuming ice cream. CONCLUSIONS: It is concluded that an increase in threshold following immunotherapy which achieves an eliciting dose of 300 or 1000 mg peanut protein is clinically relevant for the European peanut-allergic population. Benefits of an increased threshold include a significant reduction in risk due to traces of peanut protein.
Development and Evaluation of a Real-Time PCR Multiplex Assay for the Detection of Allergenic Peanut Using Chloroplast DNA Markers.
Peanut is one of the most commonly consumed allergy-causing foods in the United States. Prevention of accidental consumption by allergic individuals is assisted by methods that effectively identify the presence of peanut in food, even at trace levels. This study presents a multiplex real-time polymerase chain reaction (PCR) assay that uses chloroplast markers (matK, rpl16, and trnH-psbA) to specifically detect peanut in three types of foods: baked goods, chocolate, and tomato sauces. Food matrices were spiked with raw peanut at concentrations ranging from 0.1 to 105 ppm. The assay was evaluated with respect to linear range and reaction efficiency. High reaction efficiencies were generally obtained across 6-7 orders of magnitude. Limits of detection were between 0.1 and 1 ppm, and reaction efficiencies were mostly within the preferred range of 100 ± 10%. Our results indicate that real-time PCR assays using chloroplast markers can be a valuable tool for peanut detection.
Dietary Supplementation with Non‐Digestible Oligosaccharides Reduces Allergic Symptoms and Supports Low Dose Oral Immunotherapy in a Peanut Allergy Mouse Model.
SCOPE: A major downside of oral immunotherapy (OIT) for food allergy is the risk of severe side-effects. Non-digestible short- and long-chain fructo-oligosaccharides (scFOS/lcFOS), reduced allergy development in murine models. We therefor hypothesized that scFOS/lcFOS can also support the efficacy of OIT in a peanut allergy model. METHODS AND RESULTS: After sensitization to peanut extract (PE) using cholera toxin, C3H/HeOuJ mice were fed a 1% scFOS/lcFOS or control diet and received OIT (1.5 or 15 mg PE). Hereafter, mice were exposed to PE via different routes to determine the safety and efficacy of treatment in clinical outcomes, PE-specific antibody production and numbers of various immune cells. scFOS/lcFOS increased short-chain fatty acid levels in the caecum and reduced the acute allergic skin response and drop in body temperature after PE exposure. Interestingly, 15 mg and 1.5 mg OIT with scFOS/lcFOS induced protection against anaphylaxis, whereas 1.5 mg OIT alone did not. OIT, with or without scFOS/lcFOS, induced PE-specific IgG and IgA levels and increased CD103+ dendritic cells in the mesenteric lymph nodes. CONCLUSIONS: scFOS/lcFOS and scFOS/lcFOS combined with a low dose OIT are able to protect against a peanut-allergic anaphylactic response.
Allergy and Asthma: Food Allergies.
Food allergies are immune-mediated allergic adverse reactions that occur after exposure to specific foods. The most commonly recognized food allergies are immunoglobulin E (IgE)-mediated reactions (eg, urticaria, angioedema, anaphylaxis) that result from exposure to milk, egg, peanut, tree nuts, shellfish, fish, wheat, or soy. However, other foods can cause food allergies. Oral allergy syndrome is a common but underrecognized condition characterized by transient oropharyngeal symptoms that result from ingestion of uncooked fruits or vegetables. Non-IgE-mediated food allergies manifest with more delayed symptoms than IgE-mediated food allergies, and predominately cause gastrointestinal symptoms. Food allergies often are overreported because they may be confused with food intolerances or nonimmunologic adverse food reactions (eg, lactose intolerance, food poisoning, caffeine intolerance). Food allergies are diagnosed using IgE skin tests, IgE serum tests, or oral food challenge tests. These allergies are best managed by avoidance of the food or foods related to the allergy because they require ingestion rather than contact to precipitate symptoms. Injectable epinephrine should be prescribed for patients at risk of anaphylaxis. Careful food label reading and food preparation, awareness, and education are keys to prevention.
Jug r 6 is the allergenic vicilin present in walnut responsible for IgE cross-reactivities to other tree nuts and seeds.
Walnuts are ranked high in the list of the culprit foods inducing severe allergic reactions. Jug r 2 has been identified as a major allergen in common walnut by cDNA cloning from a somatic cell line. So far, studies were performed on the allergenic activity of recombinant Jug r 2, yet there is still no evidence about the physicochemical characteristics of the natural allergen. Therefore, we aimed to purify and deeply characterize natural Jug r 2 and to assess IgE cross-reactivity among vicilins from different tree nuts. Extensive mass spectrometry analysis of the obtained purified vicilin allowed identification of the protein sequence that displayed only 44% identity to Jug r 2. The newly identified vicilin (Jug r 6) was recognized by IgE of 26% in walnut allergic patients' sera tested. In contrast to Jug r 2, Jug r 6 displayed a remarkable level of cross-reactivity when tested with homologues from hazelnut, sesame and pistachio. It is the first report showing the necessity of proteomic studies to improve allergy component resolved diagnosis.
Simultaneous detection of eight species of tree nut in foods using two tetraplex polymerase chain reaction assays.
Tree nuts comprise a category of food allergens that must be included in the food labels in several countries. We developed a polymerase chain reaction (PCR) method using eight specific primer pairs to detect eight representative tree nuts (almond, Brazil nut, cashew, hazelnut, macadamia nut, pecan, pistachio, and walnut) under the same experimental conditions. The specificity of the eight primer pairs was confirmed by PCR testing against a variety of plant and animal samples. The detection limit of the method ranged from 1 fg to 1 pg DNA of individual tree nuts. The method detected tree nut DNA in processed and unprocessed food. In addition, the primer pairs could be combined into two sets of tetraplex PCR system. The developed method is specific, sensitive, and efficient, making it useful for detecting trace amounts of eight species of tree nut in foods.
Dietary carbohydrate intake and mortality: a prospective cohort study and meta-analysis.
BACKGROUND: Low carbohydrate diets, which restrict carbohydrate in favour of increased protein or fat intake, or both, are a popular weight-loss strategy. However, the long-term effect of carbohydrate restriction on mortality is controversial and could depend on whether dietary carbohydrate is replaced by plant-based or animal-based fat and protein. We aimed to investigate the association between carbohydrate intake and mortality. METHODS: We studied 15 428 adults aged 45-64 years, in four US communities, who completed a dietary questionnaire at enrolment in the Atherosclerosis Risk in Communities (ARIC) study (between 1987 and 1989), and who did not report extreme caloric intake (<600 kcal or >4200 kcal per day for men and <500 kcal or >3600 kcal per day for women). The primary outcome was all-cause mortality. We investigated the association between the percentage of energy from carbohydrate intake and all-cause mortality, accounting for possible non-linear relationships in this cohort. We further examined this association, combining ARIC data with data for carbohydrate intake reported from seven multinational prospective studies in a meta-analysis. Finally, we assessed whether the substitution of animal or plant sources of fat and protein for carbohydrate affected mortality. FINDINGS: During a median follow-up of 25 years there were 6283 deaths in the ARIC cohort, and there were 40 181 deaths across all cohort studies. In the ARIC cohort, after multivariable adjustment, there was a U-shaped association between the percentage of energy consumed from carbohydrate (mean 48·9%, SD 9·4) and mortality: a percentage of 50-55% energy from carbohydrate was associated with the lowest risk of mortality. In the meta-analysis of all cohorts (432 179 participants), both low carbohydrate consumption (<40%) and high carbohydrate consumption (>70%) conferred greater mortality risk than did moderate intake, which was consistent with a U-shaped association (pooled hazard ratio 1·20, 95% CI 1·09-1·32 for low carbohydrate consumption; 1·23, 1·11-1·36 for high carbohydrate consumption). However, results varied by the source of macronutrients: mortality increased when carbohydrates were exchanged for animal-derived fat or protein (1·18, 1·08-1·29) and mortality decreased when the substitutions were plant-based (0·82, 0·78-0·87). INTERPRETATION: Both high and low percentages of carbohydrate diets were associated with increased mortality, with minimal risk observed at 50-55% carbohydrate intake. Low carbohydrate dietary patterns favouring animal-derived protein and fat sources, from sources such as lamb, beef, pork, and chicken, were associated with higher mortality, whereas those that favoured plant-derived protein and fat intake, from sources such as vegetables, nuts, peanut butter, and whole-grain breads, were associated with lower mortality, suggesting that the source of food notably modifies the association between carbohydrate intake and mortality.
Walnut Supplementation in the Diet Reduces Oxidative Damage and Improves Antioxidant Status in Transgenic Mouse Model of Alzheimer’s Disease.
Our previous study has shown beneficial effects of walnuts on memory and learning skills in transgenic mouse model of Alzheimer's disease (AD-tg). To understand underlying mechanism, we studied here whether walnuts can reduce oxidative stress in AD. From 4 months of age, experimental AD-tg mice were fed diets containing 6% (T6) or 9% walnuts (T9) (equivalent to 1 or 1.5 oz, of walnuts per day in humans) for 5, 10, or 15 months. The control groups, i.e., AD-tg (T0) and wild-type (Wt) mice, were fed diets without walnuts. Free radicals, i.e., reactive oxygen species (ROS), lipid peroxidation, protein oxidation, and antioxidant enzymes were assessed in these mice at different ages. AD-tg mice on control diet (T0) showed significant age-dependent increase in ROS levels, lipid peroxidation, and protein oxidation coupled with impaired activities of antioxidant enzymes [superoxide dismutase, catalase, and glutathione peroxidase] compared to Wt mice. Oxidative stress was significantly reduced in AD-tg mice on diets with walnuts (T6, T9), as evidenced by decreased levels of ROS, lipid peroxidation, and protein oxidation, as well as by enhanced activities of antioxidant enzymes compared to T0 mice. Long-term supplementation with walnuts for 10 or 15 months was more effective in reducing oxidative stress in AD-tg mice. Our findings indicate that walnuts can reduce oxidative stress, not only by scavenging free radicals, but also by protecting antioxidant status, thus leading to reduced oxidative damage to lipids and proteins in AD. Therefore, by reducing oxidative stress, a walnut-enriched diet may help reduce the risk or delay the onset and progression of AD.
The impact of nuts consumption on glucose/insulin homeostasis and inflammation markers mediated by adiposity factors among American adults.
BACKGROUND: Inconclusive results have been published regarding the impact of nut consumption on glucose/insulin homeostasis and inflammatory factors. Furthermore, it remains unanswered whether adiposity factors could mediate the association between nut consumption, glucose/insulin homeostasis and inflammatory markers; this is what the current study aims to investigate. RESULTS: From a total of 16,784 individuals, 48.2% participants were men; overall mean age was 47.2 years. Age-, sex-, energy intake and race-adjusted mean of serum C-reactive protein (CRP)(0.49 to 0.26 mg/dl), apolipoprotein-β (apo- β) (95.6 to 90.8 mg/dl), glucose/insulin homeostasis parameters and triglyceride-glucose index (TyG) index (8.32 to 7.95) significantly decreased as the quartile of nut intake increased (all p < 0.001). We found that all evaluated potential mediators had significant and positive associations with markers of glucose/insulin homeostasis or inflammation (all p < 0.001). With regard to BMI, the mediated effects were significant for the associations between nut consumption and CRP, fasting blood glucose, insulin, hemoglobin A1c (HbA1c), triglyceride to high-density lipoprotein (TG:HDL) ratio and TyG index (all p < 0.001). As for WC, it had mediator impact on CRP, fasting blood glucose, HbA1c, TG:HDL ratio and TyG index (all p < 0.001). apVAT played no mediation role for any association (all p > 0.05). CONCLUSIONS: This is the first study which quantify the role of nut consumption on inflammatory and glucose/insulin homeostasis markers. Nut intake was inversely associated with inflammatory and glucose/insulin homeostasis markers. Certain adiposity indexes (i.e. BMI and WC) mediated these associations. These findings convey an important message for the crucial role of weight management with dietary recommendations. METHOD: We extracted data from the National Health and Nutrition Examination Survey (2005-2010) on nut consumption to evaluate the association between nut intake and markers of glucose/insulin homeostasis and inflammation. We assessed whether this link, if any, is mediated or affected by adiposity factors, including body mass index (BMI), waist circumference (WC, marker of central adiposity), anthropometrically predicted visceral adipose tissue (apVAT), visceral adiposity index (VAI, indicator of adipose distribution) and lipid accumulation product (LPA, novel index of central lipid accumulation). Analysis of co-variance and conceptus causal mediation analysis were conducted based on survey design and sample weights.