In many of the above studies, patients were reported to have subnormal B12 levels
Case Study 4: Marks Off-Label Use Mark, a 70-year-old Medicare beneficiary, had a unique situation where his doctor prescribed off-label B12 shots
[3] For example, someone with borderline thiamine and B deficiency might feel less brain fog, improved mood, and better stamina as those vitamins are replenished
tumour Biol 1991;12:353-9
Last reviewed: June 11, 2026 Last updated: June 11, 2026 Written by: Jay Hastings, CEO of PlexusDx Jay Hastings is the CEO of PlexusDx, a precision health company focused on genetic testing, blood biomarker insights, and personalized wellness recommendations
Vitamin B12 injections, when administered by our experienced healthcare professionals, are generally safe and well-tolerated for most of our patients