Vitamina D

A menudo, cuando hablamos de la vitamina D no podemos evitar pensar en los huesos, ya que es conocida por todos por ser reguladora del calcio y del fósforo.

A día de hoy, conocemos mucho más de ella.

Puede disminuir el riesgo de sufrir enfermedades, por lo que está vinculada con nuestro sistema inmunológico. También es un biomarcador pronóstico, por lo que aumenta la eficacia de los tratamientos y la supervivencia de nuestras células ante enfermedades.

¿De dónde la obtienen?

La vitamina D se produce en la piel de la mayoría de los mamíferos. En los perros, sin embargo, la evidencia sugiere que la producción de vitamina D mediada por rayos UV es esencialmente insignificante, lo que significa que en perros solo se debe contabilizar la ingesta dietética. 

En el caso de los gatos es igual, pero la necesidad de Vitamina D es menor proporcionalmente; esto puede tener su razón en que los gatos son principalmente animales nocturnos  y su metabolismo podría no depender tanto de fuentes exteriores.

  

En otro estudio se alimentaron cachorros con una dieta sin suplemento de vitamina D, desarrollando Raquitismo, que no se pudo evitar a pesar de la exposición a la luz solar.

La vitamina D se almacena en el tejido adiposo (grasa), pero también en el músculo.

Después de la ingestión o producción de la piel, la vitamina D es transportada al hígado por las proteínas transportadoras, allí sufre una transformación por las enzimas del citocromo P450 y se convierte en 25-hidroxivitamina D o 25 (OH) D.

La 25 (OH) D es uno de los metabolitos más estables de la vitamina D y se ha aceptado como un marcador de sus niveles en sangre.

Concentraciones bajas de este metabolito en sangre se asocian con un mayor riesgo de cáncer colorrectal en humanos.

La producción primaria de la forma más activa de la Vitamina D tiene lugar en los riñones por acción de una enzima (citocromo P450 27B1), pero también ocurre en muchos otros tejidos como piel, colon y páncreas, evidenciando las funciones de la vitamina D en otros tejidos aparte del esqueleto.

La producción de la vitamina D se regula por la hormona paratiroidea, la concentración de calcio en sangre, fósforo y la propia Vitamina D. La 1,25 (OH) 2D controla los niveles de calcio y fósforo del cuerpo aumentando la absorción intestinal y estimulando la movilización de los huesos entre muchas otras funciones.

Según NRC, la cantidad requerida diaria de vitamina D3 para un perro de 25Kg sería de 5µg (200 UI), pero ojo, esta medida no la podemos sacar para perros de otro peso mediante una regla de tres.

Si elegimos un suplemento de vitamina D para perros, este DEBE reflejar claramente la dosificación adecuada según el peso. Ejemplo, el aceite de hígado de bacalao.

Si hacemos una dieta casera, por ejemplo BARF, el valor requerido por el NRC se da cuando un 15-20% de la parte cárnica sea a base de pescado azul. Esto puede ser calculado y aplicado a diario o, una vez a la semana, reemplazar toda la parte cárnica por pescado azul.

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Los gatos tienen una necesidad de Vitamina D menor que la de los perros, pero también es considerado un nutriente esencial para los gatos por parte de los organismos oficiales.

Según NRC, la cantidad requerida diaria de vitamina D3 para un gato de 5Kg sería de 0.5µg (20 UI).

De nuevo, como pasa en el caso de los perros, cualquier producto que compremos debe tener señalizada claramente la cantidad de Vitamina D (en µg o en UI) en función del peso del animal.

En el caso de los gatos, por necesitar menos, sí podríamos lograr suplementar de manera natural con aceite de hígado de bacalao, con fitoplancton o con un 15-20% de pescado en su dieta.

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