Vitamin B12 (Kobalaminler)
Özet
B12 vitamini, insanlar tarafından sentezlenemeyen, dışarıdan alınması zorunlu olan ve mikroorganizmalar tarafından üretilen bir vitamindir. En önemli kaynağını karaciğer, kırmızı et, balık, süt, yumurta gibi hayvansal besinler oluşturmaktadır. DNA sentezi, sinir sisteminin miyelinizasyonu ve kırmızı kan hücrelerinin üretimi gibi kritik birçok reaksiyonda kofaktör olarak yer alıyor olması insan metabolizması için önemini arttırmaktadır. B12 vitamini eksikliğinin en sık görülen nedeni diyetle yetersiz alımdır. Eksikliğinde solukluk, halsizlik, yorgunluk, irritabilite, apati gibi sık görülen bulgular dışında tedavinin geciktiği durumlarda motor mental gelişme geriliği, letarji, nöbet hatta koma tablosu dahi görülebilmektedir. Son yıllarda eksikliği kadar fazlalığı da araştırılmaktadır. B12 vitamini yüksekliğinin en sık nedeni diyetle veya tedavi sonrası fazla alımdır. Bununla birlikte yüksek vitamin B12 düzeyleri karaciğer hastalıkları, lösemi, solid tümörler, lenfoproliferatif hastalıklar ve infeksiyonlarla da ilişkilendirilmiştir.
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