GRANO SARACENO. Pochi lo usano, ma è il più antiossidante dei cereali.
L'articolo sui pizzoccheri e le originali varianti suggerite per rendere questa stupenda pasta italiana utilizzabile da tutti in pietanze più sane e più leggere di quella standard pubblicizzata dai produttori, ha destato curiosità e interrogativi da parte di alcuni lettori, che vogliono sapere qualche riferimento alle proprietà alimentari, nutrizionali e preventive di questo piccolo seme cerealicolo dalla curiosa forma piramidale che ricorda in piccolo le faggiole, cioè i frutti del faggio (e perciò il nome botanico è Fagopyrum: fagus=faggio, pyrum=frutto).
MA E’ UN CEREALE O NO? Innanzitutto, una parentesi lessicale: il grano saraceno è un cereale, altroché, e un cereale coi fiocchi, al contrario di quanto si dice sui siti ignoranti di internet, e purtroppo perfino in qualche libro. Il grano saraceno è una piccola pianta anonima, con foglioline verdi, dai 30 agli 80 cm di altezza e per niente vistosa, che appartiene alla famiglia botanica delle Poligonaceae, ed è da secoli usato e considerato un ottimo cereale, perché – ecco l’unica definizione vera di cereale – dotato di spighe o “chicchi ricchi di amido storicamente usati dall’Uomo in piatti di resistenza come pane e polente”. Insomma, cereale non è un termine botanico, ma storico, letterario, antropologico-culturale, alimentare. Il cereale è storicamente il primo e più importante nutrimento umano: il chicco di amido che dà farina. Il nome deriva dalla mitologica dea Cerere, patrona delle mèssi e dei raccolti, soprattutto grano e semi analoghi, qualunque grano o seme o spiga mangereccia usata nei millenni dall’uomo come pasto principale. Il problema (culturale) imbarazzante è, invece, che molti credono che cereali sia sinonimo della famiglia delle Graminaceae o Poaceae (sinonimi tra loro), questi sì, termini classificatori scientifici. E perciò gli altri chicchi usati come cereali li chiamano “pseudo-cereali”! E no. Cereali come frumento, orzo, avena, miglio, riso, mais sono stati classificati nelle Graminaceae. Invece, cereali come saraceno, amaranto e quinoa fanno parte di altre famiglie botaniche.
ATTIVITA’ PROTETTIVE. Il grano saraceno è per eccellenza il cereale protettivo delle pareti dei vasi capillari e sanguigni in generale, con tutto quello che può significare, non solo riguardo alle vene varicose e alle facili ecchimosi di certe giovani donne, ma alla stessa salute dei vasi che portano sangue ai più diversi organi, come l’occhio e il cervello.
Purché integrale, è il cereale più ricco di polifenoli antiossidanti: non solo il flavonoide rutina (abbondantissima: 5-10 mg/100g), ma anche gli acidi fenolici idrossibenzoico, protocatecuico, siringico, ferulico, vanillico, cumarico, le catechine e quel famoso resveratrolo che molti credono presente solo nell’uva nera e nel vino rosso.
Tutti antiossidanti che impediscono ai grassi protettivi della cellula la disastrosa perossidazione. Utili nel ridurre i rischi di invecchiamento precoce e malattie, specialmente cardiovascolari, infiammatorie e tumorali.
Il saraceno è stato sperimentato contro i danni neuronali da ischemia sull’equilibrio e la memoria spaziale (danni all’ippocampo), e per l’attività antagonista verso il radicale ossido nitroso NO, che poi è quello che dà origine alle temibili nitrosamine cancerogene. Il saraceno interessa perciò anche neurologi, cardiologi, ematologi e oncologi.
La ricerca scientifica ne mette in evidenza l'altissimo valore antiossidante, dovuto soprattutto ai suoi numerosi polifenoli, il potere anti-cancro dei suoi inibitori delle proteasi (antitripsine), che dimostrano ancora una volta l'utilità preventiva delle sostanze antinutritive, il ruolo protettivo del selenio, di cui in media "sembra" ben dotato (diciamo "sembra", perché la presenza di selenio dipende anche dal tipo di terreno agricolo e quindi varia da zona a zona), l'azione già detta di rafforzamento dei vasi capillari, e infine l'effetto anticolesterolo e antilipidico. Ma la ricerca ha scoperto anche diversi altri possibili utilizzazioni.
Non c'è dubbio, insomma, che il saraceno, sotto forma di pizzoccheri, ma anche come polenta taragna, crespelle, sciatt, o minestra di chicchi al naturale, è un ottimo cereale e che andrebbe consumato più spesso.
APPENDICE: ALCUNI STUDI
POLIFENOLI DEL SARACENO MIGLIORANO MEMORIA DOPO ISCHEMIA NEI TOPI
Protective Effect of Buckwheat Polyphenols Against Long-Lasting Impairment of Spatial Memory Associated With Hippocampal Neuronal Damage in Rats Subjected to Repeated Cerebral Ischemia. (Fengling Pu, Kenichi Mishima, Nobuaki Egashira, Katsunori Iwasaki, Tomohiro Kaneko, Tomoko Uchida, Keiichi Irie, Daisuke Ishibashi, Hajime Fujii, Kenichi Kosuna and Michihiro Fujiwar). Journal of Pharmacological Sciences Vol. 94 (2004), 4, 393-402.
In the present experiment, we studied the action of buckwheat polyphenol (BWP, from Fagopyrum esculentum Moench) in a repeated cerebral ischemia model, which induced a strong and long-lasting impairment of spatial memory in 8-arm radial maze with hippocampal CA1 cell death in rats. BWP (600 mg/kg, continuous 21-day p.o.) significantly ameliorated not only the impairment of spatial memory in the 8-arm radial maze, but also necrosis and TUNEL-positive cells in the hippocampal CA1 area subjected to repeated cerebral ischemia (10 min × 2 times occlusion, 1-h interval) in rats. In order to investigate the mechanism of BWP protective action, we measured the release of glutamate and NOx− (NO2− + NO3−) production induced by repeated cerebral ischemia in the rat dorsal hippocampus using microdialysis. A 14-day BWP treatment significantly inhibited the excess release of glutamate after the second occlusion. In addition, the BWP remarkably suppressed a delayed increase in NOx− (NO2− + NO3−) induced by repeated cerebral ischemia in the dorsal hippocampus as determined in vivo by microdialysis. However, the 14-day treatment did not affect hippocampal blood flow in either intact rats or rats subjected to repeated ischemia measured by lasser Doppler flowmeter. These results suggested that BWP might ameliorate spatial memory impairment by inhibiting glutamate release and the delayed (ritardata) generation of NOx− in rats subjected to repeated cerebral ischemia.
GRANO SARACENO RICCO DI POLIFENOLI ANTIOSSIDANTI (DALLA RUTINA AL RESVERATROLO)
Flavonoids in fine buckwheat (Fagopyrum esculentum Mönch) flour and their free radical scavenging activities. (Qian J-; Mayer D ; Kuhn M). Deutsche Lebensmittel-Rundschau 1999, 95, 9, 343-349
Fine flours of five buckwheat cultivars, Astra and Lileja from Russia, Hruszowska from Poland, Le Harpe from France, and Prego of German native stock, introduced and cultivated in the experimental field of the University of Hohenheim, were investigated in respect of antioxidant compounds. Spectrophotometric measurements showed that the content of total antioxidants was 14.6. 21.4, 13.8, 16.0, and 11.4 mg/100 g of fine flour in Astra, Hruszowska, Le Harpe, Lileja, and Prego, respectively. Reversed-phase high performance chromatography analyses revealed protocatechuic acid and/or catechin, and resveratrol in Astra: resveratrol, protocatechuic acid and catechin in Hruszowska; resveratrol, protocatechuic acid and/or catechin in Le Harpe, resveratrol and catechin in Lileja; and resveratrol and catechin in Prego, apart from the most importantflavonoid rutin in buckwheat, whose amount was 5.6, 3.8, 10.1, 6.3, and 4.9 mg/100 g of flour in the alphabetic sequence of names of the cultivars. Further cell cultivation assay suggested that all the ethanolic extracts of buckwheat flours were apparently effective to retard free radical induced oxidation, but extracts of Astra and Hruszowska extracts were extremely significant against control, implying the origin of buckwheatcultivar determining the quality asthe total antioxidant content was different for each.
AVENA E SARACENO RIDUCONO COLESTEROLO E MIGLIORANO RAPPORTO LDL-HDL
Oats and buckwheat intakes and cardiovascular disease risk factors in an ethnic minority of China. (J He, MJ Klag, PK Whelton, JP Mo, JY Chen, MC Qian, PS Mo and GQ He). American Journal of Clinical Nutrition, 61, 366-372.
The relationship of oats and buckwheat intake to cardiovascular disease risk factors was studied in 850 Yi people, an ethnic minority in southwest China. Blood pressure was measured on 3 consecutive days. Serum total cholesterol, high-density-lipoprotein (HDL) cholesterol, and triglycerides were measured after a 14-h fast. Oats and buckwheat intakes were assessed by questionnaire. In multiple-regression analysis, oats intake (100 g/d) was associated with lower body mass index (-0.25, in kg/m2; P < 0.05), systolic (-3.1 mm Hg, P < 0.001) and diastolic (-1.3 mm Hg, P < 0.01) blood pressure, and HDL cholesterol (- 0.13 mmol/L, P < 0.001). Buckwheat intake (100 g/d) was associated with lower serum total cholesterol (-0.07 mmol/L, P < 0.01) and low-density- lipoprotein cholesterol (-0.06 mmol/L, P < 0.05) and a higher ratio of HDL to total cholesterol (0.01, P < 0.05). These findings suggest a role for oats and buckwheat consumption in the prevention and treatment of both hypertension and hypercholesterolemia.
SARACENO ABBASSA RADICALI LIBERI IN LABORATORIO CON DIETA GRASSA
Effect of buckwheat extract on free radical generation in rabbits administered high-fat diet. (J. Wójcicki, L. Samochowiec, B. Gonet, S. Juwiak, E. Dabrowska-Zamojcin, M. Katdoska, S. Tustanowski). Phytotherapy Research, 9, 5 , 323-326 1995
In this study the effect of buckwheat extract (BE) on the level of malondialdehyde (MDA), lipids and hormones, and on the concentration of ascorbate free radicals in the liver (compared with rutin) in animals receiving a highfat diet (HFD) was measured. Male mongrel rabbits were randomly divided Into four groups: (1) control, (2) animals given HFD containing cholesterol and coconut oil, (3) rabbits treated with HFD + BE, (4) HFD + rufin, over a period of 12 weeks. The concentration of MDA in rabbits of group 3 (HFD + BE) was slightly but significantly decreased, whilst the number of ascorbate free radicals, examined in vitro, in the liver was markedly elevated. The level of testosterone in rabbit blood serum (group 3) was increased, but the insulin concentration was significantly diminished (in comparison with group 2). The content of total cholesterol and triglyceride in the liver of animals maintained on BE was decreased. Quite distinct superiority of BE, compared with rutin, was shown.
SARACENO IN DIETE ANTI-ATEROSCLEROSI GRAZIE AGLI ANTIOSSIDANTI POLIFENOLI
The total polyphenols and the antioxidant potentials of some selected cereals and pseudocereals. (Shela Gorinstein, Simon Trakhtenberg et al.). Journal European Food Research and Technology, 225, 3-4 / July, 2007, 321-328.
The objective of the present study was to investigate the effect of phenolic substances and proteins on the antioxidant potentials in some cereals and pseudocereals and to compare their bioability. The polyphenol dry matter extracts (PDME) from the investigated seeds of buckwheat, rice, soybean, amaranth and quinoa with 1.2 M HCl in 50% methanol/water (PDME50%Met/HCl) exhibited higher inhibition of lipid peroxidation than the ones extracted with 50% methanol/water (PDME50%Met) and were comparable to the antioxidant activity of butylated hydroxyanisole at concentration of 0.2 mg mL−1. The antioxidant activities of these seed extracts determined by 2,2′-azinobis (3-ethylbenzothiazoline-6-sulfonate)-ABTS +/K2S2O8, β-carotene bleaching (β-carotene), and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging methods showed high correlation coefficients (R 2) such as 0.9515, 0.9058 and 0.8723, respectively, with the presence of total polyphenols estimated by Folin-Ciocalteu assay. These results indicate that the major antioxidant components in these extracts mostly derived from the polyphenols, and proteins showed only minimal values of bioactivity. Based on high contents of polyphenols, anthocyanins, flavonoids and their antioxidant activities pseudocereals such as buckwheat, quinoa and amaranth can be a substitute for cereals for common and atherosclerotic diets and sometimes in the allergic cases.
PROTEINE DEL SARACENO SOPPRIMONO CELLULE DI CANCRO AL COLON NEI RATTI
Feeding of Buckwheat Protein Suppresses 1,2-dimethylhydrazine-Induced Colon Carcinogenesis in Rats. (Hiroyuki Tomotake, Zhihe LiU, Xuxin Huang, Wakako Ishikawa, Jun Kayashita and Norihisa Kato). This study was conducted to examine the effect of consumption of buckwheat protein product (BWP) on 1,2-dimethylhydrazine (DMH)-induced colon tumor in rats. Rats were fed the diet containing either casein or BWP (net protein level, 200g/kg; each group, 20 rats) for 124 d. The rats were weekly ingested with DMH for the initial 8 wk. The food intake and growth were unaffected by dietary manipulation. Dietary BWP caused a 47% reduction in the incidence of colonic adenocarcinoma (P < 0.05). BWP intake caused a trend of reduction in the number of colon adenocarcinoma (P = 0.16). Consumption of BWP significantly reduced cell proliferation and expression of c-myc and c-fos proteins in colonic epithelium. The results suggest that dietary BWP has a protective effect against colon carcinogenesis in rats by reducing cell proliferation.
SARACENO RICCO DI SELENIO ASSIMILABILE ANTICANCRO
Selenium (Se)- enriched foods may be an effective way of consuming the amount of Se proven to reduce cancer. Buckwheat is a Se-containing grain that also may be beneficial in controlling diabetes and hypercholesterolemia. A survey of buckwheat produced in the northern Great Plains found the average Se content to be 51.6 ug Se/100g. To determine the bioavailability of Se from a commercially available buckwheat bran product, Se depleted rats were fed diets consisting of a range of concentrations of Se (0.02 - 0.15 mg Se/kg diet) supplied as selenite, selenomethionine, and buckwheat bran. Based on blood Se status indicators, approximately 50% of the Se from buckwheat was bioavailable. Therefore, a single 100g serving of buckwheat will contribute approximately 26 ug of bioavailable Se to the diet, supplying a proportion of the Recommended Daily Allowance of 55 ug/day.
ANTITRIPSINE DEL SARACENO INDUCONO APOPTOSI DI CELLULE DI LEUCEMIA
Induction of Apoptosis by Buckwheat Trypsin Inhibitor in Chronic Myeloid Leukemia K562 Cells. (Autori: Zhuan-Hua Wang, Li Gao, Yu-Ying Li, Zheng Zhang, Jing-Ming Yuan, Hong-Wei Wang, Li Zhang and Lei Zhu). Biological & Pharmaceutical Bulletin 30 (2007), 4, 783
Buckwheat is an ancient and specialty grain in China. Due to its unique chemical and bio-activity components, buckwheat has been found to have many uses in food products and medicine. However, very little is known about the toxicity of protease inhibitors from buckwheat. Here, the possible effects of a recombinant buckwheat trypsin inhibitor (rBTI) on the induction of apoptosis of the human K562 cell line were investigated by MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assays and flow cytometric analysis. MTT assay showed that rBTI could specifically inhibit the growth of K562 cells in a dose-dependent manner, but there were minimal effects on normal human peripheral blood mononuclear cells (PBMCs). Furthermore, comparison the effects of rBTI on K562 cells with those of negative control (BSA and the complex of BSA and rBTI) revealed that rBTI was highly toxic to K562 cells, and BSA hardly had any inhibition on proliferation in K562 cells. The analysis of flow cytometric indicated that the apoptosis of K562 cells were 31.0%, 32.8%, 35.3% and 52.1% after treated by rBTI in range of 12.5—100 μg/ml, respectively. The results suggested that rBTI can induce apoptosis of K562 cells and that it might be a potential protein drug of the trypsin inhibitor family.
CEREALI INTEGRALI (MA NON LE "FIBRE DIETETICHE" DELLA FARMACIA, E NON CERTO LE PATATE) PROTEGGONO DAL CANCRO AL COLON
Cereals, cereal fibre and colorectal cancer risk: a review of the epidemiological literature. (Autore: Hill MJ.). Eur J Cancer Prev. 1997 Jun; 6(3):219-25.
The large bowel is one of the major sites of cancer incidence and mortality in most western countries. In early studies most effort was expended in trying to find the causal factor, but the direction changed when Burkitt and Walker promoted the idea that the cancer could be prevented by dietary fibre (DF). Early studies to try to confirm this hypothesis were hampered by problems concerning the definition of DF, and the lack of good analytical methods to quantitate its intake. There was, however, general agreement that DF is a complex carbohydrate of plant origin that escapes small bowel digestion and so reaches the colon. It was assumed that the major plant polysaccharide, starch, is completely digested in the small bowel, but this is not true. Thus, the identity of DF as non-starch polysaccharide is not true, and other evidence suggests that it accounts for only about 25% of the true intake of DF. Assay of 'resistant starch' is fraught with difficulty and so it is better at this stage to use fibre-rich food rather than inaccurate assays of DF in epidemiological studies. In this review, I have re-examined the epidemiological literature and have found that, whereas there could be dispute over the strength of the protection given by DF, there is no doubt about the protection afforded by cereal fibre. A further analysis of data from Europe, North America and Australasia shows that the fibre-rich foods, cereals are strongly protective, as are vegetables; fruits are neutral, while starchy root vegetables, if anything, promote colorectal cancer.
[Sottolineo l’ultimo periodo, che avrà fatto sobbalzare sulla sedia più d’uno (e stiamo parlando delle conclusioni in estrema sintesi di una revisione, non recente, di numerosi studi epidemiologici-statistici precedenti effettuati sul cancro al colon in rapporto agli alimenti): "I cereali integrali sono fortemente protettivi, così come le verdure; i frutti sono neutri, mentre i tuberi amidacei – patate e patate dolci – semmai favoriscono il cancro al colon". Tutto questo, aggiungiamo noi, ovviamente, in un'ampio e prolungato quadro epidemiologico, cioè di larga statistica e nel lungo periodo. Oggi, comunque, si è arrivati a dettagli, ma anche a scetticismo, superiori].