Revista Conhecimento Online | Novo Hamburgo | a. 11 | v. 1 | jan./abr. 2019Jordana Tres Santos et al. RESUMOA vitamina C ou ácido ascórbico (AA) é um elemento essencial para o ser humano e, por não ser metabolizado pelo corpo, necessitamos da sua ingestão pela dieta e/ou suplementação. As funções do AA no corpo são inúmeras, tais como: cofator para enzimas, biossíntese de hormônios e ação antioxidante, entretanto, estudos relatam que o consumo de AA em doses elevadas pode oferecer riscos à saúde. Deste modo, buscou-se analisar os efeitos descritos da suplementação de AA. Realizamos uma revisão bibliográfica, dividida em duas perspectivas: uma histórica, com publicações de 1753 a 2012; e outra contemporânea, com estudos realizados entre 1990 e 2017. A pesquisa foi realizada no Science Direct, Scielo, PubMed, Scopus, Portal de Periódicos da Capes e em livros, utilizando as palavras-chave: vitamina C, ácido ascórbico, estresse oxidativo, antioxidante e pró-oxidante. A suplementação com AA é controversa, sendo descrito tanto o seu efeito antioxidante, como o pró-oxidante. A sua efetividade na prevenção e no tratamento do resfriado, diabete e câncer é questionável. Determinados grupos de pessoas mostram-se mais suscetíveis à toxicidade e aos danos do AA, podendo apresentar incidência de cálculos renais e interferência na função plaquetária. Concluímos que a suplementação em doses excessivas de AA pode ocasionar uma transição de um estado saudável para o patológico, desencadeando uma atividade pró-oxidante. Além disso, a dose ótima a ser ingerida e o limiar entre a dose benéfica e a prejudicial, é discutível. Desse modo, a suplementação de vitamina C deve ser realizada com cautela, com prescrição e acompanhamento de profissionais da saúde. Palavras-chave: Antioxidante. Pró-oxidante. Ácido ascórbico. Estresse oxidativo. ABSTRACTVitamin C or ascorbic acid (AA) is an essential element for humans and, because it is not metabolized by the body, we need its intake through diet and / or supplementation. The functions of AA in the body are numerous, such as: cofactor for many enzymes, biosynthesis of hormones, antioxidant action, however, studies report that the consumption of AA in high doses can pose health risks. Thus, we sought to analyze the known and reported effects of AA supplementation. We carried out a bibliographic review, divided into two perspectives: a historical one, with publications of 1753-2012; and a contemporary one, with studies conducted between 1990-2017. The research was conducted in Science Direct, Scielo, PubMed, Scopus, Capes Newspaper Portal, using the keywords: vitamin C, ascorbic acid, oxidative stress, antioxidant and pro-oxidant. Supplementation with AA is controversial, with both antioxidant and prooxidant effects being described. Its effectiveness in the prevention and treatment of colds, diabetes and cancer is questionable. Certain groups of people are more susceptible to the toxicity and damage of AA, with an incidence of renal calculi and interference with platelet function. We can conclude...

Fluoride related to caries prevention is at the center of a scientific controversy. Studies show that fluoride causes damage to health and the environment, as well as reducing IQ in children. The fluoridation of drinking water, mandatory in Brazil, has repercussions over the whole society. One of our objectives was to know the concentrations of fluoride (F) and toxic metals of Sinos River, treated water and final consumers of the cities of Campo Bom (CB), Novo Hamburgo (NH) and São Leopoldo (SL), as well as the groundwater from Ivoti, located in southern Brazil. We also evaluated in rats the effects of F and, in association with lead (Pb), on thyroid hormones and the Total Antioxidant Capacity (TAC). Three groups of rats were exposed to different waters: G1-Control with distilled water (DW); G2-DW with 25ppm (F); G3-DW with 25ppm (F) + 30 ppm (Pb). The Sinos River has an average concentration of 0.0735 mg.L-1 of F. But the F of both the water treated by the ETA of SL as well as in the final consumers of SL had concentrations above 0.9 mg.L-1 (State Ordinance No. 10/1999). In addition, we verified the presence of Pb and Cr (VI) in all types of water. The results with the animals showed a significant difference in T3 (p=0.032) and in T4 (p=0.043) from G3 to G1. In TAC, the difference was significant from G2 to G1 and G3 (p=0.007), showing that F and F with Pb interfere with the endocrine and antioxidant functions of rats. In addition, the fact that there are water fluoridation failures shows that the population is exposed to health risks. We confirm that drinking water fluoridation needs to be demystified and reconsidered as a public health intervention.