Vitamin B12 activates folate and is essential for DNA synthesis, red blood cell development and nerve cell maintenance. Overdoing folic acid supplements can mask a B12 deficiency. Symptoms of deficiency include anemia, fatigue, cognitive impairment/dementia, numbness and tingling of hands and toes, depression, swollen/ inflamed tongue, and degeneration of peripheral nerves leading to paralysis. Good dietary sources include animal proteins and fortified cereals. After having bypass and sleeve surgery, it is recommended to take B12 supplements due to decreased absorption capability.

The guidelines are (choose 1 of the following routes):

  • 350 mcg per day or 1000 mcg 3 times per week of sublingual B12
  • 500 mcg/week intranasal spray
  • 1000 mcg/month intramuscular injections.


Isom, K. A., & Majumdar, M. (2022). Pocket guide to bariatric surgery. Academy of Nutrition and Dietetics.