RESUMEN
Meat consumption and cancer has been evaluated in hundreds of epidemiologic studies over the past three decades; however, the possible role of this food group on carcinogenesis is equivocal. In this comprehensive review, the currently available epidemiologic prospective studies of red meat intake and colorectal cancer are summarized to provide a greater understanding of any potential relationships. Specifically, salient demographic, methodological and analytical information is synthesized across 35 prospective studies. Collectively, associations between red meat consumption and colorectal cancer are generally weak in magnitude, with most relative risks below 1.50 and not statistically significant, and there is a lack of a clear dose-response trend. Results are variable by anatomic tumour site (colon vs. rectum) and by gender, as the epidemiologic data are not indicative of a positive association among women while most associations are weakly elevated among men. Colinearity between red meat intake and other dietary factors (e.g. Western lifestyle, high intake of refined sugars and alcohol, low intake of fruits, vegetables and fibre) and behavioural factors (e.g. low physical activity, high smoking prevalence, high body mass index) limit the ability to analytically isolate the independent effects of red meat consumption. Because of these factors, the currently available epidemiologic evidence is not sufficient to support an independent positive association between red meat consumption and colorectal cancer.
Asunto(s)
Neoplasias Colorrectales/epidemiología , Neoplasias Colorrectales/etiología , Carne , Factores de Confusión Epidemiológicos , Dieta , Femenino , Humanos , Masculino , Carne/efectos adversos , Estudios Prospectivos , Factores de Riesgo , Factores SexualesRESUMEN
An in vivo pilot study of the oral bioavailability of polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated dibenzofurans (PCDFs) in two soils with distinct congener profiles (one dominated by PCDDs, the other by PCDFs) was conducted in rats and juvenile swine. The pilot study revealed potential confounding of relative bioavailability estimates compared to bioavailability in spiked corn oil gavage for tetrachlorodibenzofuran (TCDF) in the rat study due to differential EROD induction between groups receiving soil and those receiving spiked control PCDDs/PCDFs. A follow-up study in rats with the furan-contaminated soil was then conducted with reductions in the spiked control doses to 20%, 50% and 80% of the soil-feed dose in order to bracket hepatic enzyme induction levels in the soil group. When hepatic enzyme induction was matched between the soil and spiked control groups, the apparent relative bioavailability for TCDF was reduced significantly. Overall, after controlling for hepatic enzyme induction, estimates of relative bioavailability in rats and swine differed for the two soils. In the rat study, the relative bioavailability of the two soils were approximately 37% and 60% compared to corn oil administration for the PCDD- and PCDF- dominated soils, respectively, on a TEQ basis. In swine, both soils demonstrated relative bioavailability between 20% and 25% compared to administration in corn oil. These species differences and experimental design issues, such as controlling for differential enzyme induction between corn oil and soil-feed animals in a bioavailability study, are relevant to risk assessment efforts where relative bioavailability inputs are important for theoretical exposure and risk characterization.