Vitamin B12 is an important nutrient that helps your body make red blood cells and DNA, the genetic material in all of your cells
Even in liquid form, it will still last a year or two past the expiration date, unless it is compromised by mold
The tests performed by our doctor are a complete blood count (CBC) and a vitamin B12 blood test
(PubMed) Sato Y, Honda Y, Iwamoto J, Kanoko T, Satoh K
Although the vitamin sounds like a single vitamin, there are in fact eight B vitamins that are more of less prevalent in different foodstuffs, and regularly added as fortification to breads and cereals, for example - thiamin (B1), riboflavin (B2), niacin (B3), pantothenic acid (B5), pyridoxine (B6), biotin (B7), folate/folacin or folic acid (B9) and cobalamins (B12)