Review: State of the knowledge on the importance of folates and cobalamin for dairy cow metabolism.

Synthesis of B vitamins by the rumen microbiota is usually sufficient to avoid the appearance of clinical deficiency symptoms in dairy cows under normal feeding conditions. Nevertheless, it is now generally accepted that vitamin deficiency is much more than the appearance of major functional and morphological symptoms. Subclinical deficiency, which is present as soon as the supply is lower than the need, causes cellular metabolic changes leading to a loss of metabolic efficiency. Folates and cobalamin, two B vitamins, share close metabolic relationships. Folates act as co-substrates in one-carbon metabolism, providing one-carbon unit for DNA synthesis and de novo synthesis of methyl groups for the methylation cycle. Cobalamin acts as a coenzyme for reactions in the metabolism of amino acids, odd-numbered chain fatty acids including propionate and de novo synthesis of methyl groups. Both vitamins are involved in reactions to support lipid and protein metabolism, nucleotide synthesis, methylation reactions and possibly, maintenance of redox status. Over the last decades, several studies have reported the beneficial effects of folic acid and vitamin B12 supplements on lactation performance of dairy cows. These observations indicate that, even when cows are fed diets adequately balanced for energy and major nutrients, B-vitamin subclinical deficiency could be present. This condition reduces casein synthesis in the mammary gland and milk and milk component yields. Folic acid and vitamin B12 supplements, especially when given together, may alter energy partitioning in dairy cows during early and mid-lactation as indicated by increased milk, energy-corrected milk, or milk component yields without affecting DM intake and BW or even with reductions in BW or body condition loss. Folate and cobalamin subclinical deficiency interferes with efficiency of gluconeogenesis and fatty acid oxidation and possibly alters responses to oxidative conditions. The present review aims to describe the metabolic pathways affected by folate and cobalamin supply and the consequences of a suboptimal supply on metabolic efficiency. The state of knowledge on the estimation of folate and cobalamin supply is also briefly mentioned.

Vitamin B12 in Relation to Oxidative Stress: A Systematic Review.

The triage theory posits that modest micronutrient deficiencies may induce reallocation of nutrients to processes necessary for immediate survival at the expense of long-term health. Neglected processes could in time contribute to the onset of age-related diseases, in which oxidative stress is believed to be a major factor. Vitamin B12 (B12) appears to possess antioxidant properties. This review aims to summarise the potential antioxidant mechanisms of B12 and investigate B12 status in relation to oxidative stress markers. A systematic query-based search of PubMed was performed to identify eligible publications. The potential antioxidant properties of B12 include: (1) direct scavenging of reactive oxygen species (ROS), particularly superoxide; (2) indirect stimulation of ROS scavenging by preservation of glutathione; (3) modulation of cytokine and growth factor production to offer protection from immune response-induced oxidative stress; (4) reduction of homocysteine-induced oxidative stress; and (5) reduction of oxidative stress caused by advanced glycation end products. Some evidence appears to suggest that lower B12 status is related to increased pro-oxidant and decreased antioxidant status, both overall and for subclinically deficient individuals compared to those with normal B12 status. However, there is a lack of randomised controlled trials and prospective studies focusing specifically on the relation between B12 and oxidative stress in humans, resulting in a low strength of evidence. Further work is warranted.

Anemias ferropénicas asociadas a hemoglobinopatías en comunidades afrodescendientes en Colombia / Ferropenic anemia associated with hemoglobinopathies in Afro-descendant communities in Colombia

Resumen Objetivo. Determinar la presencia de anemias ferropénicas asociadas a hemoglobinopatías en afrodescendientes adultos colombianos habitantes de la ciudad de Tumaco, en el Departamento de Nariño y residentes de la localidad de Engativá, en Bogotá. Metodología. Las pruebas consideradas en este estudio incluyeron la valoración del hemograma automatizado, frotis de sangre periférica, proteína C reactiva, ferritina Sérica, electroforesis de hemoglobina, en 103 participantes, 23 de la comunidad afrodescendiente de Engativá y 80 de Tumaco. Esta investigación es de tipo descriptivo; por su enfoque metodológico es cuantitativa y transversal; estructurada, no experimental y correlacional, cuyo diseño muestral es estratificado, no probabilístico de tipo intencional. Resultados. La población en estudio perteneciente a la comunidad afrodescendiente ubicadas en las localidades de Tumaco, Nariño y Engativá de la ciudad de Bogotá, presentó anemia en la población femenina 28.6 % y la masculina 16.0 %. Se observó que el 9.7 % de la población en estudio, presenta hemoglobina y ferritina baja, relacionado con anemia por deficiencia de hierro y el 13.6 % presenta una deficiencia subclínica de hierro al presentar deficiencia de hierro sin anemia. Con respecto a los resultados de electroforesis de hemoglobina, el 13.6 % se evidenció con hemoglobina A2 aumentada, con posible asociación a talasemias o hemoglobinopatía C, el 0.98 % con hemoglobina S, el 0.98 % con rasgo de hemoglobina S y el 84.5 % con hemoglobina A. El 0.97 % de la población presenta ferritina baja con hemoglobina A2 aumentada, mostrando deficiencia de hierro asociada con posible hemoglobina C o talasemia y el 0.97 % de la población presenta ferritina baja con hemoglobina S. Otro hallazgo importante es la presencia de valores bajos de ferritina en el 17.8 % de las mujeres y el 4.95 % en hombres. Las variables cuantitativas se analizaron con medidas de tendencia central como el promedio y se describieron por medio de frecuencias absolutas y porcentuales.

Abstract Objective. To determine the presence of iron-deficiency anemia associated with haemoglobin disorders in adult people of African descent in the city of Tumaco, Nariño and residents of the town of Engativa, Bogota, Colombia. Methodology. The evidence considered in this study included the assessment of automated hemogram, peripheral blood, protein C reactive, ferritin serum, 103 participants, hemoglobin electrophoresis, distributed in 23 subjects in Engativá and 80 in Tumaco. This research study is descriptive; its methodological approach is quantitative and cross-sectional; structured, non-experimental and correlational, whose sample design is stratified, intentionally non-probabilistic. Results. The study community of Afro-descendants located in the towns of Tumaco Nariño and Engativa, Bogotá, present anemia in the female population of 28.6 % and in the male population of 16.0 %. It was observed that the 0.97 % of the population under study, shows hemoglobin and low ferritin, iron deficiency anemia-related. With respect to haemoglobin, at 13.6 % show increased hemoglobin A2, with possible association with thalassemia or hemoglobin C 0.98% and 0.98 % hemoglobin S. and 84.5 % with hemoglobin A, 0.97 % of the population have low ferritin with hemoglobin A2 increased, showing iron deficiency associated with possible C hemoglobin or thalassemia, and 0.97 % of the population have low ferritin with hemoglobin S. Another important finding is the presence of low levels of ferritin in 17.8 % of the women and the 4.95 % of the men indicating subclinical iron deficiency. The quantitative variables were analyzed using measures of central tendency as the average and described by means of absolute and percentage frequencies.