This uncertainty further complicates any assessment of combined use
Metabolic pathways: B12 is a cofactor in two critical reactions: Methylmalonyl-CoA mutase: Converts methylmalonyl CoA (from odd-chain fatty acids and some amino acids) into succinyl-CoA, which enters the Krebs (TCA) cycle to make ATP (cellular energy)
Providers familiar with specific syringe sizes may be more efficient and comfortable using them
If you notice signs of anaphylaxisswelling of your tongue, face, or throat, difficulty breathing, or difficulty swallowingafter getting a B12 injection, call 911 or head to the closest emergency room immediately
How a B12 deficiency causes fatigue Your cells need B12 for proper function, and without the necessary amount, your red blood cell production decreases, which makes delivering oxygen to your cells more difficult
Some people also have a hard time absorbing vitamin B12 through digestion