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DESCRIPTION: Have a question about this video? Leave it in the comment section at and I’ll try to answer it! Who should get tested for vitamin B12 (cobalamin) deficiency and which is the best test to use: serum B12, methylmalonic acid (MMA), or holotranscobalamin levels? This concludes our five-part video series on B12 this week. Please leave any questions you may have below. If you’re new to the issue, Vegan B12 Deficiency: Putting It into Perspective ( and Safest Source of B12 ( are good places to start. The consequences of B12 deficiency can be grave (see Inverted Rabbit Sign – but getting enough is easy: B12 can be taken weekly (see Cheapest Source of Vitamin B12 – or daily (see Daily Source of Vitamin B12 – See my full recommendations ( and check out the other 1000+ topics ( I cover here at NutritionFacts.org (

Image Credit: Bobjgalindo via Wikimedia Commons.

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