Are B12 molecules too big to pass through the oral mucous membranes

Vitamin B12, also known as cobalamin, is indeed a relatively large and complex molecule. Its size and structure can affect its absorption through the oral mucosa. While some nutrients can be absorbed directly through the oral mucous membranes, vitamin B12 typically requires a specific transport mechanism in the gastrointestinal tract. In terms of oral supplementation, many people take vitamin B12 in the form of sublingual tablets (which dissolve under the tongue) or as a liquid. These forms are intended to enhance absorption through the mucous membranes, although the effectiveness can vary among individuals. However, because vitamin B12 is a large molecule, it generally doesn't absorb efficiently through the oral mucosa compared to other routes, like intramuscular injection or oral ingestion where it is absorbed in the intestines with the help of intrinsic factor, a protein that binds to B12 and facilitates its absorption. Overall, while some absorption of B12 may occur through the oral mucosa, it is not very efficient compared to other methods, especially in individuals with certain conditions that affect absorption.