Estrés oxidativo, enfermedades y tratamientos antioxidantes

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Abstract

La oxidación es un proceso bioquímico de pérdida de electrones siempre asociado a otro de captación que llamamos reducción. Esta oxidación es fundamental para la vida pues participa en los procesos de obtención de la energía celular. Sin embargo cuando existe un exceso de oxidación aparece el estrés oxidativo que es una realidad compleja en todos los niveles biológicos que no se puede medir ni definir con un solo parámetro. Hay una multitud de enfermedades que se han relacionado con el estrés oxidativo y la generación de radicales libres. Por esto, terapias antioxidantes y dietas ricas (como la dieta mediterránea) o enriquecidas con antioxidantes parecen prevenir o al menos disminuir el deterioro funcional orgánico originado por un exceso de estrés oxidativo.

Translated abstract

Oxidation is a biochemical process of loss of electrons associated with another of reception called reduction. This process is capital for life, because it takes part in the production of cellular energy. Oxidative stress appears when oxidation is excessive. This reality is complex in all biological levels, and cannot be measured or defined by a single parameter. A great number of diseases have been related to oxidative stress and generation of free radicals. For this reason, antioxidant therapies and diets (such as mediterranean diet) rich or enriched with antioxidants seem to prevent or at least to attenuate the organic deterioration originated by an excessive oxidative stress.

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Most cited references 234

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Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease.

Gilbert S. Omenn, Gary Goodman, Mark Thornquist … (1996)

Lung cancer and cardiovascular disease are major causes of death in the United States. It has been proposed that carotenoids and retinoids are agents that may prevent these disorders. We conducted a multicenter, randomized, double-blind, placebo-controlled primary prevention trial -- the Beta Carotene and Retinol Efficacy Trial -- involving a total of 18,314 smokers, former smokers, and workers exposed to asbestos. The effects of a combination of 30 mg of beta carotene per day and 25,000 IU of retinol (vitamin A) in the form of retinyl palmitate per day on the primary end point, the incidence of lung cancer, were compared with those of placebo. A total of 388 new cases of lung cancer were diagnosed during the 73,135 person-years of follow-up (mean length of follow-up, 4.0 years). The active-treatment group had a relative risk of lung cancer of 1.28 (95 percent confidence interval, 1.04 to 1.57; P=0.02), as compared with the placebo group. There were no statistically significant differences in the risks of other types of cancer. In the active-treatment group, the relative risk of death from any cause was 1.17 (95 percent confidence interval, 1.03 to 1.33); of death from lung cancer, 1.46 (95 percent confidence interval, 1.07 to 2.00); and of death from cardiovascular disease, 1.26 (95 percent confidence interval, 0.99 to 1.61). On the basis of these findings, the randomized trial was stopped 21 months earlier than planned; follow-up will continue for another 5 years. After an average of four years of supplementation, the combination of beta carotene and vitamin A had no benefit and may have had an adverse effect on the incidence of lung cancer and on the risk of death from lung cancer, cardiovascular disease, and any cause in smokers and workers exposed to asbestos.

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Lack of effect of long-term supplementation with beta carotene on the incidence of malignant neoplasms and cardiovascular disease.

C Hennekens, J E Buring, J E Manson … (1996)

Observational studies suggest that people who consume more fruits and vegetables containing beta carotene have somewhat lower risks of cancer and cardiovascular disease, and earlier basic research suggested plausible mechanisms. Because large randomized trials of long duration were necessary to test this hypothesis directly, we conducted a trial of beta carotene supplementation. In a randomized, double-blind, placebo-controlled trial of beta carotene (50 mg on alternate days), we enrolled 22,071 male physicians, 40 to 84 years of age, in the United States; 11 percent were current smokers and 39 percent were former smokers at the beginning of the study in 1982. By December 31, 1995, the scheduled end of the study, fewer than 1 percent had been lost to follow-up, and compliance was 78 percent in the group that received beta carotene. Among 11,036 physicians randomly assigned to receive beta carotene and 11,035 assigned to receive placebo, there were virtually no early or late differences in the overall incidence of malignant neoplasms or cardiovascular disease, or in overall mortality. In the beta carotene group, 1273 men had any malignant neoplasm (except nonmelanoma skin cancer), as compared with 1293 in the placebo group (relative risk, 0.98; 95 percent confidence interval, 0.91 to 1.06). There were also no significant differences in the number of cases of lung cancer (82 in the beta carotene group vs. 88 in the placebo group); the number of deaths from cancer (386 vs. 380), deaths from any cause (979 vs. 968), or deaths from cardiovascular disease (338 vs. 313); the number of men with myocardial infarction (468 vs. 489); the number with stroke (367 vs. 382); or the number with any one of the previous three end points (967 vs. 972). Among current and former smokers, there were also no significant early or late differences in any of these end points. In this trial among healthy men, 12 years of supplementation with beta carotene produced neither benefit nor harm in terms of the incidence of malignant neoplasms, cardiovascular disease, or death from all causes.

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Vitamin E consumption and the risk of coronary heart disease in men.

E B Rimm, M Stampfer, A Ascherio … (1993)

The oxidative modification of low-density lipoproteins increases their incorporation into the arterial intima, an essential step in atherogenesis. Although dietary antioxidants, such as vitamin C, carotene, and vitamin E, have been hypothesized to prevent coronary heart disease, prospective epidemiologic data are sparse. In 1986, 39,910 U.S. male health professionals 40 to 75 years of age who were free of diagnosed coronary heart disease, diabetes, and hypercholesterolemia completed detailed dietary questionnaires that assessed their usual intake of vitamin C, carotene, and vitamin E in addition to other nutrients. During four years of follow-up, we documented 667 cases of coronary disease. After controlling for age and several coronary risk factors, we observed a lower risk of coronary disease among men with higher intakes of vitamin E (P for trend = 0.003). For men consuming more than 60 IU per day of vitamin E, the multivariate relative risk was 0.64 (95 percent confidence interval, 0.49 to 0.83) as compared with those consuming less than 7.5 IU per day. As compared with men who did not take vitamin E supplements, men who took at least 100 IU per day for at least two years had a multivariate relative risk of coronary disease of 0.63 (95 percent confidence interval, 0.47 to 0.84). Carotene intake was not associated with a lower risk of coronary disease among those who had never smoked, but it was inversely associated with the risk among current smokers (relative risk, 0.30; 95 percent confidence interval, 0.11 to 0.82) and former smokers (relative risk, 0.60; 95 percent confidence interval, 0.38 to 0.94). In contrast, a high intake of vitamin C was not associated with a lower risk of coronary disease. These data do not prove a causal relation, but they provide evidence of an association between a high intake of vitamin E and a lower risk of coronary heart disease in men. Public policy recommendations with regard to the use of vitamin E supplements should await the results of additional studies.

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J.I. Elejalde Guerra: Role: ND

Journal

Journal ID (publisher): ami

Title: Anales de Medicina Interna

Abbreviated Title: An. Med. Interna (Madrid)

Publisher: Arán Ediciones, S. L. (Madrid )

ISSN: 0212-7199

Publication date (Print): June 2001

Volume: 18

Issue: 6

Pages: 50-59

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[1 ] Hospital de Navarra Spain

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Publisher ID: S0212-71992001000600010

DOI: 10.4321/s0212-71992001000600010

SO-VID: 829d37bf-98cd-4c63-bde5-ba98be439067

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http://creativecommons.org/licenses/by/4.0/

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SciELO Spain

Self URI (journal page): http://scielo.isciii.es/scielo.php?script=sci_serial&pid=0212-7199&lng=en

Estrés oxidativo, enfermedades y tratamientos antioxidantes Translated title: Oxidative stress, diseases and antioxidant treatment

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Most cited references 234

Effects of a combination of beta carotene and vitamin A on lung cancer and cardiovascular disease.

Lack of effect of long-term supplementation with beta carotene on the incidence of malignant neoplasms and cardiovascular disease.

Vitamin E consumption and the risk of coronary heart disease in men.

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