Vitamin B12 Injections: Dosage and Frequency Guide Vitamin B12 deficiency, sometimes called cobalamin deficiency, happens when your body is either not getting enough or not absorbing enough vitamin B12 from the foods you eat. Vitamin B12 is an important Neurobion B12 Forte 10 Vials, 10 ml Liquid Vitamin Complex for Deficiencies, Metabolism, Immune Support Walmart.com If you're not getting enough vitamin B12 from food, a supplement can help fill the gap. Here's what experts recommend for taking it. See link below