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STUDIO DEL 2007 SULLA CHITINA, DI CUI COMPOSTI GLI ESOSCHELETRO DEGLI INSETTI
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Chitina, la sostanza contenuta negli insetti. I media ne esaltano le qualità, ma Nature: “Avvia l’infiammazione polmonare”
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La sostanza contenuta negli insetti e non completamente digeribile, negli anni è stata oggetto di studio di diverse riviste e studi. Tutti collimano verso un unico risultato: la chitina è dannosa verso chi la utilizza
Tra le sostanze presenti negli insetti, verso cui l’Ue è sempre più indirizzata per farli arrivare nei nostri piatti, c’è la chitina: questa è una sostanza, non completamente digeribile, conosciuta anche per essere il principale componente dell’esoscheletro degli artropodi. Uno studio di Nature del 2007 illustra come questa avvii “l’infiammazione polmonare innata di tipo 2 attraverso percorsi non completamente definiti”. Eppure diversi giornali fanno a gara a lodarne le qualità, smentendo o provando a smentire fatti inconfutabili.
Chitina: È gara a chi punta il dito urlando alle “fake news”
La chitina è sta inserita tra quelle sostanza antinutritive e tossiche. Non è solo la rivista inglese, per usare un eufemismo a sconsigliarne l’uso a tavola ma anche il settimanale Focus che spiega in modo molto chiaro come la sostanza abbia “effetti negativi verso la digeribilità e l’impiego delle proteine“. Un altro studio del 2017 dell’U.S. Department of Health and Human Service contenuto nel National Toxicology Program dimostra come il consumo di chitosano, composto chimico a base di chitosina, porti all’esaurimento delle vitamine.
E sono gli stessi media ad andare in cortocircuito quando spiegano che “anche se effettivamente alcune parti degli insetti effettivamente non sono digeribili, questo non significa che sarebbero dannose per la nostra salute se assunte in maniera corretta”. I motivi del perché sarebbero dannose sono tanti e le ricerche effettuate lo dimostrano. In attesa di altre.
Ue, la farina di grillo è solo il primo passo
Eppure gli insetti, che anche vengono utilizzati in molte culture del mondo come cibo, sembrano dover entrare a tutti i costi anche sulle tavole degli europei. È di pochi giorni fa infatti la decisione con cui Bruxelles ha dato il via alla farina di grillo, che servirà per creare pane, pasta, miele, barrette energetiche e biscotti. L’alimento è prodotto da una ditta vietnamita e la distribuzione partirà da un’azienda italiana che si chiama Italian Cricket Farm, residente a Scalenghe, in provincia di Torino. Il milione di grilli allevati al giorno, saluterà gli animali a cui erano destinati come mangimi per venir utilizzati per creare nuove “pietanze”.
Un altro studio americano, di PLOS ONE, molto più in generale chiarisce come “nel 30% del campione analizzato di insetti destinati all’alimentazione umana siano stati riscontrati parassiti dannosi, in particolare per polmoni e intestino“, seguendo la linea della già citata Nature.
Fonte: Il Giornale d’Italia di martedì 26 dicembre 2023
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Lettera pubblicata: 22 aprile 2007
LA CHITINA INDUCE L’ACCUMULO NEI TESSUTI DI CELLULE IMMUNITARIE INNATE ASSOCIATE ALL’ALLERGIA
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Tiffany A. Reese, Hong-Erh Liang, Andrew M. Tager, Andrew D. Lustre, Nico Van Rooijen, David Voehringer & Richard M. Locksley
Nature 447 ,92-96 (2007) 1 Cita questo articolo
7028 Accessi 593 Citazioni 1 638 Metriche alternative
Abstract
L’immunità allergica e parassitaria ai vermi è caratterizzata dall’infiltrazione di tessuti con cellule che esprimono interleuchina (IL)-4 e IL-13, comprese le cellule Thelper- 2 cellule, eosinofili e basofili-.
I macrofagi tissutali assumono un fenotipo distinto, designato macrofagi attivati alternativamente.
Si sa relativamente poco sui fattori che innescano queste risposte dell’ospite.
La chitina, un diffuso biopolimero ambientale di N-acetil-B-D-glucosamina, fornisce rigidità strutturale a funghi, crostacei, elminti e insetti.
Qui, mostriamo che la chitina induce l’accumulo nel tessuto di cellule immunitarie innate che esprimono IL-4, inclusi eosinofili e basofili, quando somministrata ai topi.
L’infiltrazione tissutale non è stata influenzata dall’assenza del riconoscimento del lipopolisaccaride mediato dal recettore Toll-like, ma non si è verificata se la chitina iniettata era stata pretrattata con la chitinasi di mammifero inducibile da 1L-4 e IL-13, AMCaset, o se la chitina è stato iniettato in topi che sovraesprimevano AMCase.
La chitina mediava l’attivazione alternativa dei macrofagi in vivo e la produzione di leucotriene B4, necessario per il reclutamento ottimale delle cellule immunitarie.
La chitina è un elemento di riconoscimento per l’infiltrazione tissutale da parte di cellule innate implicate nell’immunità allergica ed elmintica e questo processo può essere regolato negativamente da una chitinasi dei vertebrati.
Questa è un’anteprima dei contenuti in abbonamento, accessibile tramite il tuo istituto
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Letter Published: 22 April 2007
CHITIN INDUCES ACCUMULATION IN TISSUE OFINNATE IMMUNE CELLS ASSOCIATED WITH ALLERGY
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Tiffany A. Reese, Hong-Erh Liang, Andrew M. Tager, Andrew D. Luster, Nico Van Rooijen, David Voehringer & Richard M. Locksley Nature 447,92-96 (2007) 1 Cite this article 7028 Accesses 593 Citations 1 638 Altmetric Metrics Abstract Allergic and parasitic worm immunity is characterized by infiltration of tissues with interleukin (IL)-4-and IL-13-expressing cells, including Thelper-2 cells, eosinophils and basophils-. Tissue macrophages assume a distinct phenotype, designated alternatively activated macrophages . Relatively little is known about the factors that trigger these host responses. Chitin, a widespread environmental biopolymer of N-acetyl-B-D-glucosamine, provides structural rigidity to fungi, crustaceans, helminths and insects’. Here, we show that chitin induces the accumulation in tissue of IL-4-expressing innate immune cells, including eosinophils and basophils, when given to mice. Tissue infiltration was unaffected by the absence of Toll-like-receptor-mediated lipopolysaccharide recognition but did not occur if the injected chitin was pre-treated with the 1L-4- and IL-13-inducible mammalian chitinase, AMCaset, or if the chitin was injected into mice that overexpressed AMCase. Chitin mediated alternative macrophage activation in vivo and the production of leukotriene B4, which was required for optimal immune cell recruitment. Chitin is a recognition element for tissue infiltration by innate cells implicated in allergic and helminth immunity and this process can be negatively regulated by a vertebrate chitinase. This is a preview of subscription content, access via your institution
Fonte:
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QUI INVECE UNO STUDIO DEL 2019 CHE EVIDENZIA COME NEL 30% DEL CAMPIONE ANALIZZATO DI INSETTI DESTINATI ALL’ALIMENTAZIONE UMANA SIANO STATI RISCONTRATI PARASSITI DANNOSI, IN PARTICOLARE PER POLMONI E INTESTINO.
STUDIO DEL 2017 IN BASE AL QUALE IL CONSUMO DI CHITOSANO, COMPOSTO CHIMICO A BASE DI CHITOSINA, PORTA ALL’ESAURIMENTO DELLE VITAMINE.
NTP Technical Report on the Toxicity Study of Chitosan (CASRN 9012-76-4) Administered in Feed to Sprague Dawley [Crl:CD(SD)] Rats
Toxicity Report 93
NTP Toxicity Report
National Toxicology Program.
Author Information and Affiliations
Research Triangle Park (NC): National Toxicology Program; 2017 Dec.
View this report on the NTP website
Abstract
Chitosan is a cationic carbohydrate polymer that is commercially derived from the deacetylation of chitin obtained from seafood shells. The most widespread route of human exposure to chitosan is as a dietary supplement for body weight reduction. Chitosan was nominated by the National Cancer Institute for mechanistic studies designed to measure the potential for vitamin E depletion and osteoporosis following ingestion. Male and female Sprague Dawley rats were exposed to chitosan (86.5% deacetylated, with an average molecular weight of approximately 82 kilodaltons and estimated to be approximately 94% pure) in feed for 6 months.
In this 6-month study, groups of 10 male and 10 female core study rats (Group A) were fed control diets (AIN-93M) or diets containing chitosan at concentrations of 1%, 3%, or 9%, for up to 25 weeks. Two additional groups of 10 male and 10 female rats (Groups B and C) were given the same dietary concentrations for up to 26 weeks. All male and female Group A rats survived to the end of the study. Mean body weights and feed consumption of exposed Group A groups were similar to those of the control groups. Dietary concentrations of 1%, 3%, and 9% resulted in average daily doses of approximately 450, 1,500, and 5,200 mg chitosan/kg body weight per day to males and 650, 1,800, and 6,000 mg/kg per day to females. There were no treatment-related clinical findings in core study animals.
The 9% male and female rats had significantly decreased cholesterol values (26% to 48%), compared to the controls, at all time points. Triglycerides were significantly decreased in 9% male and female rats, but not at every time point. Phosphorus levels were significantly decreased in 9% male rats at weeks 13, 19, and 25; a decrease also occurred in 3% males at week 13. Phosphorus levels were significantly decreased in 3% and 9% females at weeks 13 and 25.
Compared to those of the controls, serum vitamin A concentrations were significantly decreased (approximately 30%) at weeks 13, 19, and 26 in 9% males, at weeks 13 and 26 in 3% males (approximately 15%), and at weeks 19 and 26 in 9% females (approximately 20%). Serum vitamin E concentrations were significantly decreased at all time points in 3% (33% to 42%) and 9% (79% to 82%) males, in 1% (17%) males at week 13, and in 9% (62% to 65%) females at all time points. Hepatic vitamin E concentrations were significantly decreased at week 26 in 3% (48%) and 9% (87%) males and 9% (80%) females. Serum concentrations of 1,25 (OH)2 vitamin D were significantly increased in 9% (105% to 142%) males and (100% to 180%) females at weeks 7, 19, and 26.
Compared to the control groups, percent fat digested was significantly decreased during week 6 in 9% males and females, during week 12 in 3% and 9% males, during week 18 in 9% males and females, and during week 24 in all exposed groups of males and females. Calcium absorption was significantly increased in 9% females during weeks 12 and 24. Fecal weight was significantly increased in 3% and 9% males and females during each collection period, and in 1% females during weeks 12, 18, and 24. Fecal moisture was significantly increased in 9% males (up to 170%) and 9% females at all time points, in 3% males during week 6, and in 3% females during weeks 12 and 18.
Results of this study did not support chitosan as a cause of bone resorption. Significant elevation of parathyroid hormone levels occurred occasionally and inconsistently, while calcium levels remained relatively stable. Bone calcium, bone length, and the histology findings did not indicate calcium loss from the bone following chitosan exposure.
The absolute and relative liver weights of 9% males and females and the absolute and relative thymus weights of 3% males and 9% males and females were significantly less than those of the control groups.
There was a treatment-related decrease in the incidence of periportal fatty change in the liver of 9% females relative to the control group. A decreased incidence of periportal fatty change was observed in the liver of 9% males relative to the control group as well, but this decrease was not significant, and it was the same as that observed in 1% males. The appearance of periportal fatty change was similar in both males and females and in both exposed and control groups.
Under the conditions of the 6-month feed study of chitosan, male and female rats fed 3% and 9% chitosan in the diet had significantly decreased levels of serum vitamin A and serum and hepatic vitamin E and increased levels of serum 1,25 (OH)2 vitamin D. Consumption of high levels of chitosan decreased percentage fat digestion and increased fecal weight and moisture, as well as reduced levels of phosphorous, cholesterol, and triglycerides. Female rats exposed to 9% chitosan also had significant liver weight and histologic changes. Based on the above results, the lowest-observed-effect level for chitosan exposure was 1% (approximately equivalent to 450 mg/kg) in male and 9% (approximately equivalent to 6,000 mg/kg) in female rats.
Synonyms:
2-Amino-2-deoxy-beta-D-glucosamine; deacetylated chitin; poliglusam; poly (D-glucosamine)
Trade names:
Celox, Chicol, Chitopearl, CTFA 04299, Flonac N, Kytex H, Sea Cure F
Summary of Findings Considered to be Toxicologically Relevant in Sprague Dawley Rats Exposed to Chitosan in Feed for Six Months
Link: https://www.ncbi.nlm.nih.gov/books/NBK552709/
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LA CHITINA E’ UN INSETTICIDA
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Vabbè…..(!)
La chitina degli insetti non è solo usata in agricoltura come insetticida, ma ci fanno pure l’antigelo “usano preferibilmente le cimici, e quando un caro amico me l’ha detto sono rimasto sconcertato” (!)
Ora avete pensato a cosa vi fa mangiare il ministro all’agricoltura?
Siete contenti per il nuovo madeinitaly ??