--- title: "Mitos e fatos sobre a vitamina B12 - IVU - International Vegetarian Union" description: "Mitos e fatos sobre a vitamina B12: por Valerie Copeland De TVS A maioria dos que optaram pela dieta vegetariana sabe que os vegetarianos vivem mais, têm menor incidência de câncer e menor risco de ataques e doenças do coração. As refeições" url: "https://ivu.org/international-vegetarian-union/resources/interviews/6411-portuguese-trans-tvs-b12.html" date: "2026-11-06T00:15:56+00:00" language: "en-GB" --- # Mitos e fatos sobre a vitamina B12 ![Mitos e fatos sobre a vitamina B12](https://ivu.org/images/legacy/history/banners/portuguese-trans-tvs-b12.png) | **Mitos e fatos sobre a vitamina B12** por Valerie Copeland De **[TVS](http://www.trianglevegsociety.org/)** A maioria dos que optaram pela dieta vegetariana sabe que os vegetarianos vivem mais, têm menor incidência de câncer e menor risco de ataques e doenças do coração. As refeições vegetarianas (e vegans inclusive) fornecem as quantidades adequadas de todos os nutrientes que precisamos - com a possivel exceção da Vitamina B-12, que é importante na produção de hemácias e na manutenção do sistema nervoso. A B-12 é uma vitamina essencial que é produzida somente por microorganismos tais como bactérias, fungos e algas; animais e plantas não podem sintetizar B-12 (os animais são fontes de B-12 para os não-vegetarianos porque animais ingerem microorganismos). Os vegetais que não são lavados também podem conter quantidades significativas se estiverem contaminados com bactérias produtoras de B-12. No entanto, em países desenvolvidos, onde os vegetais são lavados durante a colheita, essas bactérias são facilmente perdidas. A necessidade da Vitamina B-12 é pequena. A dose diária recomendada é de 2 microgramas (mcg), e os estudiosos acreditam que 1 mcg/dia pode ser suficiente \[1\]. A deficiência é rara, já que nossos organismos normalmente armazenam suprimentos de B-12 para vários anos, conservando-a e reabsorvendo-a dos nossos resíduos. De longe, o problema mais comum com relação à B-12 não é a deficiência na dieta, mas sim a incapacidade que uma minoria de pessoas tem de absorvê-la devido à deficiências enzimáticas; essas pessoas podem receber injeções periódicas de B-12. Devemos consultar um médico se sentirmos que pode haver uma deficiência de B-12 em nosso organismo. A dose necessaria é pequena e a deficiência é rara ... As fontes de B-12 incluem cereais enriquecidos, leite de soja enriquecido, suplementos e levedura nutritiva enriquecida. Os lacto-ovo-vegetarianos que ingerem uma variedade de alimentos não têm problema em atender todas as necessidades vitamínicas, incluindo a B-12. Os lacto-vegetarianos também têm pouca dificuldade em obter B-12 em suas dietas. Entretanto, os vegans podem sofrer de deficiência de B-12 se não fizerem o esforço consciente de incluir uma fonte confiável de B-12 em suas dietas. Vários do alimentos que se pensava que continham B-12, na realidade não a contêm, ou contêm apenas substâncias similares à B-12 mas que não possuem atividade biológica e podem até inibir a absorção de B-12. Os seguintes alimentos não contêm B-12 ou contêm apenas substâncias similares à B-12 \[2\]: Tempeh Amarante (Pau-roxo) Tamari Shoyu Espinafre Misô Alfafa Nabo Ameixa Japonesa (Umeboshi) Alga Legumes Tofu Espirulina (tipo de alga) Amendoim Malte de Cevada Confrey Feijão de Soja Pão Sourdough Água de Chuva Cogumelos Shiitake As fontes confiáveis de B-12 podem ser encontradas facilmente em vários cereais enriquecidos, leite de soja enriquecido (como o Eden Soy Extra), alguns substitutos da carne ("carne" e "hamburguer" vegetais) e todos os suplementos multivitamínicos comuns (veja se o rótulo consta do seu nome científico "Cianocobalamina"). As leveduras nutritivas enriquecidas, tais como a Red Star T6635 (uma colher de sopa fornece 4 mcg) tambem são uma fonte excelente. Esses produtos podem ser encontrados em algumas lojas de alimentação integral, como o Harmony Farms, Wellspring Grocery, e Weaver Street Market. \_\_\_\_\_\_\_\_\_\_\_\_ \[1\] Herbert, V. (1988) Vitamina B-12: fontes vegetais, doses necessárias e análise. (Vitamin B12: Plant Sources, Requirements, and Assay) Am J Clin Nutr 1988, 48:852-858. \[2\] Messina, M. and Messina, V. (1996) no livro O Guia do Nutricionista para as Dietas Vegetarianas, Questões e Aplicações (The Dietitian's Guide to Vegetarian Diets, Issues and Applications). Aspen Publishers, Inc., Gaithersburg, MD, pag. 168. --- Tradução: Fernando Mendes | A note on this archive. The history section of this website is drawn from a body of legacy content originally compiled by John Davis, former manager of the International Vegetarian Union. It represents his curation of historical material, and in places includes passages written by him directly. Over the years, the IVU website has migrated between several different hosting servers. In the course of these migrations, a number of PDF files were unfortunately lost, and **some links to PDF documents may no longer function**. 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