[727]
Mi è capitato di sfogliare Starbene e, nonostante sia evidente l'aura di scientificità che cerca di darsi, con tanto di collaborazioni con "esperti", a me continua a dare l'impressione di un settimanale da spiaggia.
Il problema è che chi lo compra dà invece molta importanza a
ciò che vi trova scritto. Mia zia è una di queste e soffre di
osteoporosi, ma nel settimanale ho trovato un'affermazione che non
può in alcun modo distoglierla dall'idea che l'opinione pubblica si
è fatta per far regredire questa patologia. Non si accenna
propriamente alla malattia, ma all'importanza di introdurre il
calcio nella dieta (ovviamente si fa riferimento ai latticini), poi
si trova scritto che assumendo solo calcio "vegetale" si
introducono anche delle sostanze che ne alterano il metabolismo e
che quindi sarebbe opportuna una integrazione. Non vi chiedo di
rispondermi su questo punto perchè mi avete già risposto in una
precedente domanda, volevo solo farvi notare un'altra perla del
genio umano che si può trovare nei mezzi di "informazione".
La mia domanda è un'altra: nello stesso numero si trova scritto che
una ricerca svolta ad Harvard conclude che "la carne rossa non fa
venire il cancro del seno", una "buona notizia", si legge.
Tralasciando la mancanza di terminologia scientifica (si può dire
che una certa sostanza non aumenta il rischio/ non è implicata
nell'insorgenza, ma evidentemente conoscono bene i termini da usare
per colpire nel segno) a me interessa quanto mi sapete dire a
riguardo. Volevo anche sottolineare che la "buona notizia" può al
massimo riferirsi al cancro al seno, non al carcinoma del colon,
che rimane tra i primi per incidenza e mortalità nel mondo
occidentale. [N.V.]
Risposta a cura della dott.ssa LUCIANA BARONI, Presidente SSNV
Su cancro al colon non ci piove. Per quanto riguarda il cancro alla mammella, le amine eterocicliche che si producono durante la cottura delle carni si ritrovano nel latte (DeBruin LS, 2003) e sono dei potenti carcinogeni, implicati nella genesi di molti tumori, tra cui pancreas, mammella e prostata. Il rischio dipende dall'interazione con fattori genetici.
Per la mammella, la gran parte degli studi trovano un'associazione per le donna in post-menopausa:
Mutat Res. 2002 Sep 30;506-507:9-20.
Comments on the history and importance of aromatic and heterocyclic amines in public health.
Weisburger JH.
American Health Foundation, 1 Dana Road, Valhalla, NY 10595, USA. jweisbur@ahf.orgThe carcinogenic risk of aromatic amines in humans was first discovered when a physician related the occurrence of urinary bladder cancer to the occupation of his patients. They were employed in the dyestuff industry, chronically exposed to large amounts of intermediate arylamines.... Interest in this class of compounds increased when of Sugimura and colleagues discovered the formation of mutagens at the surface of cooked meat or fish, that were identified as heterocyclic amines (HCAs). These compounds undergo the same type of activation reactions, as do other arylamines. Epidemiological data suggest that meat eaters may have a higher risk of breast and colon cancer. The formation of HCAs during cooking can be decreased by natural and synthetic antioxidants, by tryptophan or proline, or by removing the essential creatine through brief microwave cooking prior to frying or broiling. The amounts of HCAs in cooked foods are small, but other components in diet such as omega-6-polyunsaturated oils have powerful promoting effects in target organs of HCAs. On the other hand, the action of HCAs may be decreased by foods containing antioxidants, such as vegetables, soy, and tea. Some constituents in foods also induce phase II enzymes that detoxify reactive HCA metabolites. Additional mechanisms involved decreased growth of neoplasms by intake of protective foods. Possibly, the carcinogenic effect of HCAs is accompanied by the presence of reactive oxygen species (ROS), which are also inhibited by antioxidants. World-wide, there have been many contributors to knowledge in this field. Adequate information may permit now to adjust lifestyle and lower the risk of human disease stemming from this entire class of aryl and HCA.
Cancer Epidemiol Biomarkers Prev. 2000 Sep;9(9):905-10.
N-Acetyltransferase-2 genetic polymorphism, well-done meat intake, and breast cancer risk among postmenopausal women.
Deitz AC, Zheng W, Leff MA, Gross M, Wen WQ, Doll MA, Xiao GH, Folsom AR, Hein DW.
Department of Pharmacology and Toxicology, University of Louisville School of Medicine, Kentucky 40292, USA.Heterocyclic amines found in well-done meat require host-mediated metabolic activation before initiating DNA mutations and tumors in target organs. Polymorphic N-acetyltransferase-2 (NAT2) catalyzes the activation of heterocyclic amines via O-acetylation, suggesting that NAT2 genotypes with high O-acetyltransferase activity (rapid/intermediate acetylator phenotype) increase the risk of breast cancer in women who consume well-done meat. To test this hypothesis, DNA samples and information on diet and other breast cancer risk factors were obtained from a nested case-control study of postmenopausal women. Twenty-seven NAT2 genotypes were determined and assigned to rapid, intermediate, or slow acetylator groups based on published characterizations of recombinant NAT2 allozymes. NAT2 genotype alone was not associated with breast cancer risk. A significant dose-response relationship was observed between breast cancer risk and consumption of well-done meat among women with the rapid/intermediate NAT2 genotype (trend test, P = 0.003) that was not evident among women with the slow acetylator genotype (trend test, P = 0.22). These results suggest an interaction between NAT2 genotype and meat doneness, although a test for multiplicative interaction was not statistically significant (P = 0.06). Among women with the rapid/intermediate NAT2 genotype, consumption of well-done meat was associated with a nearly 8-fold (odds ratio, 7.6; 95% confidence interval, 1.1-50.4) elevated breast cancer risk compared with those consuming rare or medium-done meats. These results are consistent with a role for O-acetylation in the activation of heterocyclic amine carcinogens and support the hypothesis that the NAT2 acetylation polymorphism is a breast cancer risk factor among postmenopausal women with high levels of heterocyclic amine exposure.
Environ Mol Mutagen. 2002;39(2-3):184-92.
Carcinogen-DNA adducts in human breast epithelial cells.
Gorlewska-Roberts K, Green B, Fares M, Ambrosone CB, Kadlubar FF.
National Center for Toxicological Research, Jefferson, Arkansas 72079, USA.Diet and environmental exposures are often regarded as significant etiologic factors in human breast cancer. Chemicals that may be involved in these exposures include heterocyclic amines, aromatic amines, and polycyclic aromatic hydrocarbons, which also serve as strong mammary carcinogens. In this study, we chose to quantify the major DNA adducts derived from one member of each of these classes of carcinogens, that is, 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 4-aminobiphenyl (ABP), and benzo[a]pyrene (B[a]P), respectively, in DNA isolated from exfoliated ductal epithelial cells in human breast milk. Milk was collected from healthy, nonsmoking mothers. The isolated DNA was digested to 3' nucleotides and subjected to (32)P-postlabeling. Adduct enrichment was achieved using Oasis Sep-Paks and the analyses were conducted by HPLC using radiometric detection. Critical to the analyses were the syntheses of bis(phosphate) standards for the C8-dG adducts of PhIP and ABP, and the N(2)-dG adduct of B[a]P, which were added to each reaction as UV markers. Of the 64 samples analyzed, adducts were found in 31 samples. Thirty samples contained detectable levels of PhIP adducts, with a mean value of 4.7 adducts/10(7) nucleotides; 18 were positive for ABP adducts with a mean value of 4.7 adducts/10(7) nucleotides; and 13 were found to contain B[a]P adducts with a mean level of 1.9 adducts/10(7) nucleotides. These data indicate that women are exposed to several classes of dietary and environmental carcinogens and that these carcinogens react with DNA in breast ductal epithelial cells, the cells from which most breast cancers arise.
