For more in depth information on potential side effects, read this article from WebMD
Methionine is needed to make creatine, a nutrient naturally found primarily in muscle tissue that provides the energy our muscles need to move, and has been found to boost athletic performance during short, intense workouts
So are B12 shots the answer to restoring health in those with low levels
The ideal candidate for B12 injections include those who are deficient in B12, at risk of being deficient in B12, or those with signs of fatigue, weakness, or cognitive deficits
[5] There is essentially no risk of B-induced neuropathy at the doses used here, especially given the limited duration most patients use injectable therapy
Vitamin B12 is not considered dangerous for most men, but excessive supplementation may mask underlying health issues, such as folate deficiency, if not managed with proper medical supervision