Medications PCOS Supplements Type 2 Diabetes

Does Metformin Cause Vitamin B12 Deficiency?

Have you ever wondered: does Metformin cause vitamin B12 deficiency? Dr. Erica Schulte, a clinical psychologist and weight management researcher, is here to help.

Have you ever wondered: does Metformin cause vitamin B12 deficiency?

I’m here to share what science says, as well as some incredible ways to boost your B12!

As an Amazon Associate, I may earn from qualifying purchases.

Symptoms of B12 Deficiency

Vitamin B12 is a key player in your energy levels and mood, and it also makes your DNA and red blood cells! Here are the main signs of B12 deficiency that you may notice:

  • Changes to mood, such as irritability, apathy, or depression
  • Decreases in energy levels, making it feel like it is harder to get through your tasks each day
  • Tingling in the hands and feet
  • Pale skin
  • Increased heart rate
  • Difficulty walking or maintaining a normal gait
  • Dizziness and/or shortness of breath

In addition to the physical consequences of B12 deficiency, the potential psychological consequences on your energy and mood are particularly concerning to me. If you ever feel like it is difficult to follow through with tasks you have planned, including tasks related to healthy eating or activity, there may be a biological cause like B12 deficiency.

Remember, the only way to actually be diagnosed with a B12 deficiency is to speak to your doctor.

Metformin and B12: The Science

Metformin is one of the most commonly prescribed medications for individuals who have type 2 diabetes or polycystic ovarian syndrome (PCOS). Metformin is strongly backed by research as an effective medication for managing blood sugar.

However, the science does show that long-term use of Metformin is associated with a deficiency in B12 levels. A 2016 study by Aroda and colleagues, published in the Journal of Clinical Endocrinology and Metabolism, found that “…there was a 13% increased risk of vitamin B12 deficiency per year of total metformin use.” Another study published in 2019 noted that between 6-30% of patients who are taking Metformin have a B12 deficiency.

Overall, the science shows that B12 deficiency is common among patients who are taking Metformin. Check out some easy ways to increase your B12 levels below.

Boost Your B12!

The easiest ways you can get more B12 are through the foods you eat or with supplements.

Foods that are rich in B12 include animal products, like beef, chicken, fish, eggs, and dairy. Some plant-based foods are also fortified to have B12, such as non-dairy milk and protein bars. If you feel like you may experience mild symptoms of B12 deficiency, a good first step is to eat more of these foods that are naturally high in B12.

However, if you have been taking Metformin for a long period of time, you may consider talking to your doctor about including supplements in your diet.

My personal favorite B12 supplement (that I also take!) is called “Methyl Balance” and is produced by Klaire Labs. This company develops its formulas with physicians to make sure that the supplements are in the form most easily absorbed by your body. Methyl Balance not only contains B12 but also B6, B2, and folate. The combination of these vitamins in Methyl Balance provides solid support for your energy levels and mood.

Learn more about this B12 supplement here!

Klaire Labs Methyl Balance

Here are some more options you can explore for B12 supplements that have also been specially formulated to be easily absorbed by your body.

Dr. Schulte’s Summary:

If you are on Metformin, I encourage you to speak to your healthcare providers about getting tested for B12 deficiency. The good news is that there are ways you can boost your B12 through the foods you eat or with excellent supplements like Methyl Balance!

Questions? Drop a comment below or send an email to!


Aroda, V. R., Edelstein, S. L., Goldberg, R. B., Knowler, W. C., Marcovina, S. M., Orchard, T. J., Bray, G. A., Schade, D. S., Temprosa, M. G., White, N. H., Crandall, J. P., & Diabetes Prevention Program Research Group (2016). Long-term Metformin Use and Vitamin B12 Deficiency in the Diabetes Prevention Program Outcomes Study. The Journal of clinical endocrinology and metabolism101(4), 1754–1761.

Kim, J., Ahn, C. W., Fang, S., Lee, H. S., & Park, J. S. (2019). Association between metformin dose and vitamin B12 deficiency in patients with type 2 diabetes. Medicine98(46), e17918.

Disclaimer: all opinions are my own and are not affiliated with my employers. Please seek medical guidance before pursuing weight loss or making significant changes to the way you eat or your physical activity routine.

6 replies on “Does Metformin Cause Vitamin B12 Deficiency?”

Erica, I am actually on Metformine but have never known that it causes Vitamin B12 Deficiency. I have some of the symptoms you mentioned for B12 deficiency like pale skin, itches, and dizziness. Please, I will like to know if anyone on Metformine can use the Methyl Balance without a prior check-up. I ask because my doctor is now on vacation.

Hi Dr. Mau,
Thank you so much for your question! I would of course encourage you to chat with your doctor about starting any supplements. However, I have yet to come across anyone who experienced negative side effects from the Methyl Balance supplement. It was highly recommended to me by Dr. Mark Hyman, who is very selective about only consuming high-quality ingredients.

I also take it myself and have found it works wonders for potential issues with B12 deficiency. Please let me know if you try it, and I really hope it helps combat the effects of Metformin! 

Hi Erica,
Thank you for this educational article, vitamin B12 plays a good role in our body system. Even if your article doesn’t state that the long term use of metformin causes deficiency in diabetic persons. The science of it that you have quoted give glimpse of that. If most of the persons using metformin in long term are tested with B12 deficiency then fingers can be pointed to it. As someone that have a uncle that is diabetic, I must share this with him for precautions.

Hi Nsikan,

Yes, I totally agree! I always hesitate to overstate the science to say that Metformin definitely causes vitamin b12 deficiency, but I certainly believe that the overlap rate is suspect! I would strongly encourage you to share the Methyl Balance recommendation with your uncle. It has been a game-changer for myself and many others I’ve worked with!

Hi. I have been experiencing more and more problems in this area over recent years. I am still somewhat lucky in that I have been able to deal with these issues by changing my diet and exercise. So while I have had prediabetic symptoms, also low vitamin D for some years, then recently in one annual checkup my B12 was so low I had to receive a course of injections to restore it. Since then I take B12 supplements in addition to vitamin D. Just recently I have been making another change to my diet to try to reduce my cholesterol and avoid having to take medication. I have experienced low B12 symptoms and they are well worth avoiding. Thanks for sharing this, out of necessity I’ve learned more on these issues in recent years of blood chemistry than I ever imagined. Best regards, Andy

Of course, Andy! Thank you for sharing your experiences. If you are looking for a bioavailable B12 supplement, I would encourage you to give Methyl Balance a try. The quality of the ingredients can’t be beat, so you’re warding off those B12 deficiency symptoms for life!

Leave a Reply

Your email address will not be published.