Efeito da suplementação com vitamina E sobre a concentração de alfa-tocoferol no colostro humano / Effect of vitamin E supplementation on alpha-tocopherol levels in human colostrum

OBJETIVO: Avaliar a concentração de alfa-tocoferol no colostro humano em condições de suplementação com cápsulas de vitamina A acrescidas de vitamina E sintética. MÉTODOS: Foram recrutadas para o estudo 30 parturientes saudáveis atendidas em uma maternidade pública. Após jejum noturno, foram coletadas amostras de sangue e de colostro (2 mL) das parturientes. Após a primeira coleta, as mesmas receberam suplemento na forma de uma cápsula de palmitato de retinila (200000 UI ou 60 mg) acrescido de vitamina E sintética (49,4 mg de dl-alfa-tocoferol). Após 24 horas da suplementação, foi realizada nova coleta de 2 mL de colostro, também em jejum. RESULTADOS: A concentração sérica de alfa-tocoferol foi de 1 042,9 ± 319,0 μg/dL. Os teores de alfa-tocoferol no colostro antes da suplementação foram de 1155,4 ± 811,0 μg/dL, vs. 1396,3 ± 862,2 μg/dL 24 horas depois da suplementação (P > 0,05). Foi encontrada correlação entre o alfa-tocoferol do colostro na condição de jejum antes da suplementação e 24 horas após a suplementação (P = 0,001; r = 0,58), mas não entre soro e o colostro em nenhuma das condições acima citadas. CONCLUSÕES: Não houve aumento na concentração de alfa-tocoferol do colostro 24 horas após a suplementação. Isso indica que não é vantajoso suplementar a mãe com vitamina E sintética. Entretanto, os resultados também sugerem que, se o estado nutricional prévio à suplementação estiver adequado, mais tocoferol será encontrado no colostro após a suplementação. Novos estudos devem ser realizados para investigar o efeito da suplementação com a forma natural do alfa-tocoferol.

OBJECTIVE: To assess the levels of alpha-tocopherol in human colostrum following supplementation with capsules containing vitamin A plus synthetic vitamin E. METHODS: Thirty healthy women about to give birth were recruited from a public maternity hospital. After overnight fasting, blood samples as well as colostrum samples (2 mL) were collected. After the first collection, the women received supplementation with a capsule containing retinyl palmitate (200 000 IU or 60 mg) plus synthetic vitamin E (49.4 mg dl-alpha tocopherol). Twenty-four hours after supplementation, a second 2 mL colostrum sample was collected after overnight fasting. RESULTS: The serum concentration of alpha-tocopherol was 1 042,9 ± 319.0 µg/dL. The concentration of alpha-tocopherol in colostrum before supplementation was 155.4 ± 811.0 µg/dL, vs. 1 396.3 ± 862.2 µg/dL 24 hours after supplementation (P > 0.05). A correlation was found between fasting levels of alpha-tocopherol in colostrum before supplementation and 24 hours after supplementation (P = 0.001; r = 0.58), but not between the concentrations in serum and colostrum. CONCLUSIONS: There was no increase in the levels of alpha-tocopherol in colostrum 24 hours after supplementation. This suggests that supplementation with synthetic vitamin E is not advantageous. However, the present results also suggest that if the nutritional state is adequate prior to supplementation, more tocopherol will be available in colostrum after supplementation. Further studies should be carried out to investigate the effects of supplementation with the natural form of alpha-tocopherol.

Radicales libres y antioxidantes en la prevención de enfermedades, III: evidencias clínico epidemiológicas de los riesgos y beneficios asociados al consumo de antioxidantes en la prevención de enfermedades cardiovasculares / Free radicals and antioxidants in disease prevention, III: clinical and epidemiological evidences of the risks and benefits associated with antioxidant consumption in cardiovascular disease prevention

La presente actualización constituye la tercera parte de una serie de artículos publicados en esta revista sobre radicales libres y antioxidantes en nutrición, salud y patologá humana. En los artículos referidos, los autores han realizado una detallada descripción y discusión de los principales mecanismos de generación de radicales libres en el organismo, de sus acciones tanto biológicas como deletéreas, y de aquellos mecanismos de defensa antioxidante encargados de la remoción de dichas especies radicalarias. De estas revisiones se ha desprendido que, si bien la formación controlada de radicales libres es un evento continuo de carácter fisiológico, la existencia de un desbalance a favor de la generación de especies radicalarias respecto a la velocidad con que dichas especies son removidas (estrés oxidativo) puede conducir a la oxidación masiva de susbtratos biológicos. Se estableció que si bien el estrés oxidativo per se no es sinonimo de daño, la cronicidad de este evento a nivel celular/tisular puede estar involucrado en la etiogénesis y/o en el desarrollo de numerosas patologías entre las que destacan las enfermedades cardiovasculares y diversos tipos de cáncer. Esto último ha constituido la base racional para intentar establecer asociaciones entre el nivel de ingesta de antioxidantes dietarios y la prevención de dichas enfermedaes. En esta tercera revisión, centrándose en enfermedades cardiovasculares, los autores han intentado recoger en forma concisa las princiipales evidencias científicas, de carácter epidemiológico y clínico, en torno a los potenciales beneficios y riesgos asociados al consumo de antioxidantes (ya sea dietario o como suplemento)

In vivo metabolism of alpha-tocopherol in lipoproteins and liver: studies on rabbits in response to acute cholesterol loading

Objective: To investigate the transport of alpha-tocopherol in lipoproteins of rabbits under normal diet and under acute loading of cholesterol. Design: Two New Zealand White rabbits were fed (14)C-alpha-tocopherol acetate in a single oral dose and the recovery of radiolabel in lipoproteins and plasma was monitored. Low density lipoprotein (LDL) from these animals was obtained and labeled with [(3H)] cholesteryl ester. Three other rabbits were injected with this double-labeled LDL in the native form; while three other animals received this LDL in the acetylated form. Results: Plasma clearance, live uptake and levels of radiolabel in high dinsity lipoprotein (HDL) of animals injected with (14)C[(3H)]acetyl LDL were significantly higher than those in animals injected with (14)C[(3H)] native LDL. Larger particles of HDL, rich in apolipoprotein E (apoE) carried significantly higher levels of both labels in rabbits injected with acetylated LDL. Conclusion: These results provide evidence for in vivo mechanisms of "reverse alpha-tocopherol transport", analogous to "reverse cholesterol transport".

Efecto de la suplementación de las vitaminas C y E en la dieta del pollo de engorda sobre los parámetros productivos y la respuesta inmune / Effect of vitamin C and E supplementation in the diet of broilers chicks on performance and immune response

Se evaluó la adicción de las vitaminas C y E en el alimento de iniciación y finalización (1-28 y 29-56 días de edad) sobre los parámetros productivos y la respuesta inmune del pollo de engorda. Se seleccionaron 1,6000 pollos de estirpe Indian River X Peterson de la misma incubadora, que se distribuyeron en 4 tratamientos con 4 repeticiones de 100 pollos cada una. Los tratamientos fueron la dieta base o testigo o con suplementación entre de 200 ppm de vitamina C + 74,000 U.I. de vitamina E/ton. Los parámetros evaluados fueron los productivos, así como los perfiles inmunológicos a través de niveles de anticuerpos como una respuesta primaria y secundaria a glóbulos rojos de borrego (GRB), Brucella abortus (Ba) y a la vacuna de virus vivos modificado (VVM) y muerto de newcastle (VM). Los tratamientos fueron similares en cuanto a peso corporal, consumo de alimento, conversión alimenticia y mormalidad. En todos los antígenos usados para evaluar la respuesta primaria, el testigo presentó títulos menores mostrando diferencia significativa a los 21 días posinoculación; para GRB a favor de la adicción conjunta de vitamina C + E (5.6 vs 2.4), Ba (12.4 vs 0) y para VVM a favor de la adición de vitamina E (5.4 vs 4.4). La respuesta secundaria fue favorable para los tratamientos donde se administraron las vitaminas. Para GRB, hubo una diferencia a los 7 días posinoculación de la segunda aplicación a favor de la vitamina C + E (24 vs. 6.4); para Ba hubo una respuesta a los 7 días posinoculación de la primera aplicación a favor de la vitamina C (35.2 vs. 19.2) y para VM la respuesta secundaria fue mejor con vitamina C + E a los 7 días posinoculación de la segunda aplicación (7.8 vs. 6.4) y a los 14 días posinoculación (8.6 vs 7.0). Los resultados indican que las adiciones extras de las vitaminas C y E en dietas para pollo de engorda mejoran la respuesta inmunológica

Effect of vitamins C and E intake on plasma lipid concentrations in rats

Changes in the plasma lipid levels were investigated among rats fed an atherosclerotic-promoting diet containing 0.5% cholesterol and rats fed the same diet with added vitamin C [ascorbic acid], vitamin E [a-tocopherol] and vitamins C + E from one to seven weeks. Total cholesterol [TC] and triglycerides [TG] were significantly increased in rats fed a hyperlipidemic diet from the third week to the seventh week, whereas high density lipoprotein cholesterol [HDL-C] was not affected. Rats supplemented with 5 mg vitamin C, 5 mg vitamin E or 5 mg vitamin C + 5 mg vitamin E per day for four to seven weeks showed significant decrease in the concentration of TC and TG. HDL-C was only affected at the seventh week with vitamin C alone, whereas it was significantly increased with vitamin E alone and vitamins C + E at five to seven weeks. However, supplementation of vitamins C, E or C + E for less than four weeks has no significant effect on plasma lipid concentrations. The antioxidant effect of vitamins C and E is probably a time-dependent process that significantly lowers plasma lipids between week four and week seven following administration of these vitamins. It is therefore suggested that the incidence of coronary heart disease [CHD] may be reduced in lowering plasma lipid levels by dietary supplementation of vitamins C or E