Additional information Peer review information Nature Metabolism thanks Dominique Langin and the other, anonymous reviewers for their contribution to the peer review of this work
Im on my fifth shot and Im feeling great
The correct approach: Test serum B12, MMA, and homocysteine not just serum B12 Use the functional cutoff of 500 pg/mL for optimal status, not the labs lower limit of 200 pg/mL Identify the cause diet, malabsorption, medication, or autoimmune Match the supplementation protocol to the cause and severity Retest to confirm response, and continue monitoring if the underlying cause persists If youre over 50, vegan, taking metformin or PPIs, or experiencing unexplained fatigue, brain fog, or neuropathy get tested
The immune response to the vaccine is thought to come from the muscle as it absorbs the vaccine