Without testing, there is no way to distinguish between B12 deficiency and other causes of similar symptoms, no way to determine the severity of deficiency, and no way to select the most appropriate delivery method
Additionally, a randomized, double-blind, placebo-controlled trial in 2,588 healthy older adults with mild hyperhomocysteinemia found that daily supplementation with 500 g of vitamin B 12 and 400 g of folic acid for two years reduced blood homocysteine concentrations but had no benefit on depressive symptoms in those with or without depressive symptoms at baseline (110)
A severe deficiency depletes faster while your body catches up
Hormone disruption: It doesn't affect testosterone, estrogen, thyroid, or other hormones
Since your body needs to absorb the vitamin gradually, it can take several hours or even a few days before you notice any difference
The standard diagnostic pathway includes a serum B12 blood test as the initial screening tool