Folatos y vitamina B12 en la salud humana / Folate, vitamin B12 and human health

During the past decade the role of folate and vitamin B12 in human nutrition have been under constant re-examination. Basic knowledge on the metabolism and interactions between these essential nutrients has expanded and multiple complexities have been unraveled. These micronutrients have shared functions and intertwined metabolic pathways that define the size of the "methyl donor" pool utilized in multiple metabolic pathways; these include DNA methylation and synthesis of nucleic acids. In Chile, folate deficiency is virtually nonexistent, while vitamin B12 deficiency affects approximately 8.5-51% depending on the cut-off value used to define deficiency. Folate is found naturally mainly in vegetables or added as folic acid to staple foods. Vitamin B12 in its natural form is present only in foods of animal origin, which is why deficit is more common among strict vegetarians and populations with a low intake of animal foods. Poorfolate status in vulnerable women of childbearing age increases the risk of neural tube birth defects, so the critical time for the contribution of folic acid is several months before conception since neural tube closure occurs during the first weeks of life. The absorption of vitamin B12 from food is lower in older adults, who are considered to have higher risk of gastric mucosa atrophy, altered production of intrinsic factor and acid secretion. Deficiency of these vitamins is associated with hematological disorders. Vitamin B12 deficiency can also induce clinical and sub-clinical neurological and of other disorders. The purpose of this review is to provide an update on recent advances in the basic and applied knowledge of these vitamins relative to human health.

Megaloblastic anemia: Back in focus.

Megaloblastic anemia (MA), in most instances in developing countries, results from deficiency of vitamin B12 or folic acid. Over the last two to three decades, incidence of MA seems to be increasing. Of the two micronutrients, folic acid deficiency contributed to MA in a large majority of cases. Now deficiency of B12 is far more common. In addition to anemia, occurrence of neutropenia and/or thrombocytopenia is increasingly being reported. Among cases presenting with pancytopenia, MA stands out as an important (commonest cause in some series) cause. This article focuses on these and certain other aspects of MA. Possible causes of increasing incidence of MA are discussed. Observations on other clinical features like neurocognitive dysfunction, associated hyperhomocysteinemeia and occurrence of tremors and thrombocytosis during treatment are highlighted.

Papel del ácido fólico en la etiología de las anemias megaloblásticas / Role of folic acid in the etiology of megaloblastic anemias

Se hace una revisión sobre el metabolismo de los folatos, su estructura química, fuentes dietéticas y requerimientos diarios en lso diferentes grupos de edades y estados patológicos, así como su absorción y distribución en el organismo. Se expone además la función matabólica del ácido fólico y su papel etiológico en el desarrollo de las anemias megaloblásticas, las causas de la deficiencia de este metabolilto y su tratamiento