Incidence rates of non-Hodgkin's lymphoma (NHL) increased substantially in the United States and worldwide during the latter part of the 20(th) century, but little is known about the etiology of this condition. Antioxidant nutrients may reduce the risk of NHL by quenching free radicals, which may contribute to carcinogenesis by damaging DNA and lipid membranes. We examined the association of intake of vitamin A and antioxidant nutrients with risk of NHL and its major subtypes in 1,104 cases of NHL identified among 154,363 postmenopausal women followed for an average of 11 yr in the Women's Health Initiative. Cox proportional hazards models were used to estimate hazard ratios (HR) and 95% confidence intervals (CI). Of all nutrients examined, only total vitamin A intake (from diet and supplements combined) was inversely associated with risk of NHL overall (multivariate adjusted HR for highest vs. lowest quartile 0.83, 95% CI 0.69-0.99), whereas total vitamin C intake was inversely associated with risk of diffuse large B-cell lymphoma (HR for highest vs. lowest quartile 0.69, 95% CI 0.49-0.98). Overall, this study provides some evidence of inverse associations of intake of total vitamin A and total vitamin C with the risk of NHL and diffuse lymphoma, respectively.
[Show abstract][Hide abstract] ABSTRACT: Reactive oxygen species (ROS) exert various biological effects and contribute to signaling events during physiological and pathological processes. Enhanced levels of ROS are highly associated with different tumors, a Western lifestyle and nutritional regime. The supplementation of food with traditional antioxidants was shown to be protective against cancer in a number of studies both in vitro and in vivo. However, recent large scale human trials in well nourished populations did not confirm the beneficial role of antioxidants in cancer, whereas there is a well established connection between longevity of several human populations and increased amount of antioxidants in their diets. Although our knowledge about ROS generators, ROS scavengers, and ROS signaling has improved, the knowledge about the direct link between nutrition, ROS levels and cancer is limited. These limitations are partly due to lack of standardized reliable ROS measurement methods, easily useable biomarkers, knowledge of ROS action in cellular compartments, and individual genetic predispositions. The current review summarizes ROS formation due to nutrition with respect to macronutrients and antioxidant micronutrients in the context of cancer and discusses signaling mechanisms, used biomarkers and its limitations along with large scale human trials.
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