Thank you for your article. I've been on vitamin B12 injections for life since 2009. My B12 deficiency is neurological; my body does not produce enough B12 naturally to create myelin sheath around my spinal cord. B12 deficiency is dangerous and can lead to paralysis, dementia, and psychosis if untreated. Don't ignore the symptoms: painful tingling, numbness, toe curling, twitching, calf spasms, and the inability to walk and to run. I would be incapacitated or worse with out B12 injections. Here's my B12 deficiency story on Medium https://ultramiriam.medium.com/living-and-running-with-painful-b12-deficiency-e478f42fa0e0?sk=f5e8e4d18371eb73b9f5cb16475919a6