I recommend: at least 2,000 mcg (g) cyanocobalamin once each week, ideally as a chewable, sublingual, or liquid supplement taken on an empty stomach or at least 50 mcg daily of supplemental cyanocobalamin or a serving of B12-fortified foods three times a day, each containing at least 190 percent of the Daily Value listed on the nutrition facts label Those over 65 years of age should take at least 1,000 mcg (g) cyanocobalamin every day
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)
It lowers blood glucose levels, but the underlying metabolic impairment, the cells inability to respond efficiently to insulin, remains
Not the subcortical regions
Several factors likely contribute to variable results