Energy
Methylmalonic Acid
What This Marker Tells Us
Methylmalonic acid accumulates when vitamin B12 is insufficient, providing the most sensitive and specific test for true B12 deficiency at the cellular level.
Why It Matters
Detects B12 deficiency earlier and more reliably than serum B12 because it measures functional deficiency, which is inadequate B12 for cellular metabolism. Serum B12 can appear normal while tissues are deficient. B12 deficiency causes irreversible neurological damage, cognitive decline, anemia, fatigue, and elevated homocysteine increasing cardiovascular risk. MMA rises before blood counts change or neurological symptoms appear, enabling early intervention preventing permanent damage.
How to Interpret Your Trends
Low or typical MMA (below 0.4 µmol/L) indicates adequate cellular B12 status. Borderline MMA (0.4-0.5 µmol/L) suggests marginal B12 adequacy requiring attention. Elevated MMA (above 0.5 µmol/L) confirms B12 deficiency requiring treatment. Very high levels indicate severe deficiency with urgent treatment needed to prevent neurological damage. Kidney disease also elevates MMA, complicating interpretation.
What Influences This Marker
Inadequate B12 intake from vegan or vegetarian diets elevates MMA. Malabsorption from low stomach acid, pernicious anemia, intestinal disease, or medications like metformin and PPIs impair B12 absorption. Aging reduces absorption capacity. Kidney disease elevates MMA independent of B12 status. Adequate B12 intake, addressing malabsorption, and supplementation when needed maintain normal levels.
How Your Team Uses It
Your coach uses MMA to definitively diagnose B12 deficiency, particularly when serum B12 is borderline or symptoms suggest deficiency despite normal B12. Elevated MMA triggers immediate B12 supplementation and investigation of underlying absorption issues. It monitors treatment effectiveness, confirming adequate cellular B12 restoration.
Related Signals We Also Review
Vitamin B12, homocysteine, complete blood count, kidney function, gastric antibodies, and neurological symptoms complete the B12 status assessment.