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🧪 Supplement

Vitamin B12

B12 matters enormously when you are actually deficient — deficiency causes real neurological harm — and very little when you are not. The trial evidence for supplementing replete people to improve cognition is largely null. Serum B12 reads high on methylated supplements, so MMA or homocysteine are the informative tests.

The 2 claims about Vitamin B12

Each keeps its own verdict — we never average them away.

Educational only, not medical advice. Hub descriptions are curated for honesty; see the methodology.