Vitamins E and C in the prevention of cardiovascular disease and cancer in men.
- SourceAvailable from: Inès Birlouez-Aragon[Show abstract] [Hide abstract]
ABSTRACT: The recommended dietary allowance (RDA) of vitamin C has traditionally been based on the prevention of the vitamin C deficiency disease, scurvy. While higher intakes of vitamin C may exert additional health benefits, the limited Phase III randomized placebo-controlled trials (RCTs) of vitamin C supplementation have not found consistent benefit with respect to chronic disease prevention. To date, this has precluded upward adjustments of the current RDA. Here we argue that Phase III RCTs-designed principally to test the safety and efficacy of pharmaceutical drugs-are ill suited to assess the health benefits of essential nutrients; and the currently available scientific evidence is sufficient to determine the optimum intake of vitamin C in humans. This evidence establishes biological plausibility and mechanisms of action for vitamin C in the primary prevention of coronary heart disease, stroke, and cancer; and is buttressed by consistent data from prospective cohort studies based on blood analysis or dietary intake and well-designed Phase II RCTs. These RCTs show that vitamin C supplementation lowers hypertension, endothelial dysfunction, chronic inflammation, and Helicobacter pylori infection, which are independent risk factors of cardiovascular diseases and certain cancers. Furthermore, vitamin C acts as a biological antioxidant that can lower elevated levels of oxidative stress, which also may contribute to chronic disease prevention. Based on the combined evidence from human metabolic, pharmacokinetic, and observational studies and Phase II RCTs, we conclude that 200 mg per day is the optimum dietary intake of vitamin C for the majority of the adult population to maximize the vitamin's potential health benefits with the least risk of inadequacy or adverse health effects.Critical reviews in food science and nutrition 09/2012; 52(9):815-29. DOI:10.1080/10408398.2011.649149 · 5.55 Impact Factor
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ABSTRACT: Coal mining and incineration of solid residues of health services (SRHS) generate several contaminants that are delivered into the environment, such as heavy metals and dioxins. These xenobiotics can lead to oxidative stress overgeneration in organisms and cause different kinds of pathologies, including cancer. In the present study the concentrations of heavy metals such as lead, copper, iron, manganese and zinc in the urine, as well as several enzymatic and non-enzymatic biomarkers of oxidative stress in the blood (contents of lipoperoxidation = TBARS, protein carbonyls = PC, protein thiols = PT, α-tocopherol = AT, reduced glutathione = GSH, and the activities of glutathione S-transferase = GST, glutathione reductase = GR, glutathione peroxidase = GPx, catalase = CAT and superoxide dismutase = SOD), in the blood of six different groups (n = 20 each) of subjects exposed to airborne contamination related to coal mining as well as incineration of solid residues of health services (SRHS) after vitamin E (800 mg/day) and vitamin C (500 mg/day) supplementation during 6 months, which were compared to the situation before the antioxidant intervention (Ávila et al., Ecotoxicology 18:1150-1157, 2009; Possamai et al., Ecotoxicology 18:1158-1164, 2009). Except for the decreased manganese contents, heavy metal concentrations were elevated in all groups exposed to both sources of airborne contamination when compared to controls. TBARS and PC concentrations, which were elevated before the antioxidant intervention decreased after the antioxidant supplementation. Similarly, the contents of PC, AT and GSH, which were decreased before the antioxidant intervention, reached values near those found in controls, GPx activity was reestablished in underground miners, and SOD, CAT and GST activities were reestablished in all groups. The results showed that the oxidative stress condition detected previously to the antioxidant supplementation in both directly and indirectly subjects exposed to the airborne contamination from coal dusts and SRHS incineration, was attenuated after the antioxidant intervention.Ecotoxicology 10/2010; 19(7):1193-200. DOI:10.1007/s10646-010-0503-2 · 2.50 Impact Factor
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ABSTRACT: In the complex mechanism of preeclampsia, oxidative stress is an important pathogenic factor, and F₂-isoprostane is a marker of oxidative stress and lipid peroxidation. The objective of this study was to identify if the amniotic fluid (AF) levels of F₂-isoprostanes were elevated in women who later developed preeclampsia. In this study, we analyzed AF F₂-isoprostane concentrations with enzyme immunoassay (EIA), and the EIA results could be validated by quantitative mass spectrometry. The mean AF concentration of F₂-isoprostanes was significantly higher in pregnancies with subsequent development of preeclampsia (123.1 ± 57.6 pg/ml, n = 85) than in controls (73.8 ± 36.6 pg/ml, n = 85). The AF elevation of F₂-isoprostanes was even higher in the preeclampsia with intrauterine growth restriction group (138.3 ± 65.2 pg/ml, n = 39). The area under the curve of the receiver operating characteristics analysis for AF F₂-isoprostanes assay was 0.81, supporting its potential as a biomarker for preeclampsia. These results indicate that oxidative stress existed before the onset of clinical preeclampsia, further suggesting that the elevation of AF F₂-isoprostanes may be used as a guide for antioxidant supplementation to reduce the risk and/or severity of preeclampsia.Free Radical Biology and Medicine 05/2011; 50(9):1124-30. DOI:10.1016/j.freeradbiomed.2011.01.022 · 5.71 Impact Factor