Cobamide Fingerprints in Foods: A Molecular Framework for Re-Evaluating Dietary Vitamin B ₁₂ Sources

Vitamin B 12 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 B 12 by detecting inactive corrinoids. This Perspective proposes cobamide fingerprinting, defined as the proportion of biologically active vitamin B 12 (B 12 %) relative to total corrinoids, as a framework for evaluating dietary vitamin B 12 sources. Foods with similar total corrinoid contents may differ substantially in nutritional value depending on cobamide composition, portion size, and consumption patterns.