More information about vitamin B12 levels

To understand more about vitamin B12, it’s important to understand the measurement itself. We estimate vitamin B12 deficiency by measuring Methylmalonic acid levels (MMA). MMA is a compound that metabolizes B12, and is used up when B12 is processed in the body. This means that higher levels of MMA are associated with insufficient B12, and low levels of MMA are associated with high levels of B12. That being said, it is actually not possible for us to determine whether there is “excess” B12 in the blood, as the lowest possible MMA measurement is zero. 

Some reasons why you might be low in B12 include:

  • A diet low in animal products (including vegetarian or vegan diets), as meat is a common source of the vitamin. You can learn more about food sources of B12 here.
  • B12 declines as age increases
  • You have a condition of the small intestine that would impair absorption (such as IBD or Celiac disease)
  • Certain medication can affect B12 metabolism- check with your doctor or pharmacist to see if this applies to you

Supplementation: Baze dietitians recommend a supplement for those who measure below our optimal range, unless you requested to remove it.

If you still have questions about your vitamin B12 measurement, chat with one of our dietitians by emailing

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