Perhaps there is a distinction I'm missing between time to clearance of the injected B12 and the half-life of B12 when in plasma
Abstract Background This systematic review and network meta-analysis aimed to evaluate the three different administration routes of vitamin B12: oral, intramuscular (IM), and sublingual (SL) routes
This could be due to a variety of reasons such as genetic factors, underlying health conditions like pernicious anaemia, or gastrointestinal surgery
Dr Thornber advised: Vitamin B12 should be used with caution if you have any of the following conditions - heart concerns, high blood pressure, history of cancer, skin disorders, genitourinary concerns, gastrointestinal concerns, blood disorders, low serum levels of potassium, and history of gout. He added: If youre eating a balanced and healthy diet you should get enough B12 from your food including, meat, fish, dairy products, and eggs
Stomach acid drops with age, intrinsic factor production drops with it, and dietary B12 absorption follows