(Thats why vitamin B12 is often treated with B12 injections fewer barriers to absorption!) A different small study on people who underwent gastric bypass surgery found that higher doses of oral B12 supplements (1,000 to 2,000 mcg) are about as effective as injections
Patients should verify that their vials arrive cold and should transfer them to refrigeration without delay
If your B12 levels are low, this recycling system becomes less efficient
Conditions include alcoholic liver disease, viral hepatitis, cirrhosis, and primary or metastatic liver cancer Renal dysfunction : Impaired kidney function reduces B12 elimination, causing accumulation even with normal intake Haematological conditions : Myeloproliferative neoplasms, chronic myeloid leukaemia, polycythaemia vera, and hypereosinophilic syndrome increase transcobalamin production, elevating total serum B12 Laboratory interference : Macro-B12 (immunoglobulin-bound B12) and assay interference can cause spuriously elevated results without true excess In clinical practice, unexplained hypercobalaminaemia should prompt investigation for underlying disease, particularly in patients without obvious supplementation history

[4] However, consistently taking large amounts of vitamins from multiple sources could potentially increase the risk of side effects (for example, very high vitamin B intake from multiple supplements over time can cause neuropathy, and high niacin from many sources could affect your liver)