Cobamide Fingerprints in Foods: A Molecular Framework for Re-Evaluating Dietary Vitamin B12 Sources.

Vitamin B12 is synthesized exclusively by certain bacteria and archaea and is generally absent from unfortified plant-derived foods. However, food composition data often rely on microbiological assays that lack chemical specificity and may overestimate nutritionally relevant vitamin B12 by detecting inactive corrinoids. This Perspective proposes cobamide fingerprinting, defined as the proportion of biologically active vitamin B12 (B12%) relative to total corrinoids, as a framework for evaluating dietary vitamin B12 sources. Foods with similar total corrinoid contents may differ substantially in nutritional value depending on cobamide composition, portion size, and consumption patterns.