Depending on your product, unmixed (dry) methylcobalamin vials should be stored following product instructions
In the UK, deficiency is particularly prevalent among older adults, vegans, and those with gastrointestinal disorders
This impairment of DNA synthesis affects the rapidly dividing cells of the bone marrow earlier than other cells, resulting in the production of large, immature, hemoglobin-poor red blood cells (macrocytosis), as well as effects on white blood cells, including abnormal (hypersegmented) neutrophils and reduced overall cell counts (pancytopenia)
However, those with allergies may face some side effects that may lead to something serious
If you are a strict vegan, for example, you are more likely to suffer deficiencies of various nutrients