Who is at risk of B12 Deficiency?

It isn’t uncommon that I see a patient admitted to nursing home with advanced dementia and a very low level of vitamin B12. I always wonder how much of vitamin B12 deficiency may be contributing to the progression of dementia, even though it isn’t the cause. I am not a big fan of any vitamin supplements but Vitamin B12 is one where I would advocate supplementation where indicated.

Check out the blog post by Dr. P Skerrett at the Harvard Health Blog on vitamin B12 deficiency. It pretty much sums up what I feel is important to know on this topic.


Here are my thoughts on B12 supplementation:

  • A common scenario I see all the time is that individuals on metformin for Type 2 diabetes do not routine check for their vitamin B12 levels. Metformin itself can affect the absorption of B12 and as such, can lead to deficiency over time. There should be more specific guidelines to ensure Vitamin B12 level is routinely monitored.
  • We used to feel that vitamin B12 should be given via IM injection as oral absorption may not be sufficient. However, this view was recently refuted given new evidence to suggest oral supplement of Vitamin B12 1000-2000mcg per day is as good as IM injection,
  • If oral B12 is just as good, then ODB should pay for oral B12, instead of the multidose B12 injectables which only get used for 1 dose per patient per month – it’s a waste of resources to pay for a multidose vial, nursing administration time as well as related supplies (needles, syringes), not to mention the infliction of pain during the injection.
  • If you ever go to the pharmacy looking for Vitamin B12, the tablet strength available ranges from 100mcg, 250mcg to 1000mcg or 1200mcg. Do we really need to make it in that many strengths? Not only would it confuse the public, selecting a supplement too low isn’t doing anyone any good.

Do you have any experience related to Vitamin B12 deficiency? I look forward to hearing your experience.

Thank you for reading my post.



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My name is Cynthia Leung and I am a practicing pharmacist in Kingston Ontario, Canada. This blog is for me to share my ideas, opinions and perspectives on how medications are used in our health care system. Note that these posts are my own opinions and do not represent the opinions of my current or former employers and / or organizations that I may belong to. Any possible case scenarios described in my posts would be modified to maintain patient confidentiality. This blog is not a platform for professional advise for patients or health care providers and the content is not meant to support any clinical decisions or replace professional opinions. Also the images are either taken or created by the author, or adapted with permission. I hope you will enjoy reading my posts!

2 thoughts on “Who is at risk of B12 Deficiency?”

  1. I have read some stuff on FMS/fatigue related to B12 deficiency. I got checked for it, and am mildly deficient. I used to take vitamin B12 shots and it didn’t seem to do much good, so we stopped. Now I take a multivitamin with B12 a part of it. I am not sure it helps with my FMS but I figured it would be worthwhile to not be deficient in it either!

    Liked by 1 person

  2. Hey there the b12 amount in a multivitamin is usually very low – usually not enough to correct any deficiency. So it may be still worthwhile to check your b12 level. I don’t think there is an established link between b12 deficiency and FMS but B12 deficiency may contribute to neuropathy. There may be a connection that is yet to be discovered. Thank you for your comment and reading my post.


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