A whole-food plant-based diet needs Vitamin B 12. This vitamin is necessary to prevent nerve disorders, anemia and psychiatric disorders. Some people take supplements, while others take the Red Star form of nutritional yeast or fortified foods. Deficiency does not have any early symptoms and make take years to develop. Once developed, the symptoms can be irreversible. This scared me and I spent many hours researching this topic. Unfortunately, controversy exists over how much Vitamin B 12 to take, making it difficult to know the exact correct does.
Dr. Neil Barnard, from the Physicians Committee for Responsible Medicine, presented a talk called, "Nutrition Essentials:What Every Clinician Needs to Know" in July 2017 at his annual conference. Here is the link https://www.nutritioncme.org/course/3225/takecourse He mentioned that the dose was 2.4 mcg/day, which is the Recommended Daily Allowance.
He stated that if clinicians have a suspicion that their client is not taking Vitamin B 12, the clinician should order a Vitamin B 12 test, methylmalonic Acid (MMA), or homocysteine. The Vitamin B 12 test is covered OHIP. However, the MMA and homocysteine are not. There are active and inactive forms of Vitamin B 12. I went to https://www2.gov.bc.ca/…/practiti…/bc-guidelines/vitamin-b12 and learned that the Vitamin B 12 test may not correlate with symptoms of deficiency. MMA is a more sensitive test, but is not covered by OHIP. Your doctor must be willing to write you a prescription, so that you can claim it on your private insurance plan.
Dr. Michael Greger, at https://nutritionfacts.org/…/vitamin-b12-recommendation-ch…/ did a series on Vitamin B 12 from Feb 3-8, 2012. He looked into the 2.4 mcg daily amount and found that the science was based on only seven people. He believes that 4-7 mcg/day is necessary to be absorbed by the body . Absorption by the body is different than the amount you take. The body has receptors to absorb Vitamin B 12. However, these receptors can only absorb 1.5 mcg at a time. However, more Vitamin B 12 can passively be absorbed at a rate of 1%. This is good news! Thus, you can take 2500 mcg/week or 250 mcg/day sublingual (dissolves under the tongue) or orally. Sublingual and liquid forms of Vitamin B 12 tend to be more expensive. I am not a big fan of once a week dosing. There is too much chance of forgetting your weekly dose.
Please take a Vitamin B 12 supplement if you are any of the following: eating a whole-foods, plant-based or vegan diet over the age of 50 on strong acid blocking medications taking metformin have Irritable Bowel Syndrome or Inflammatory Bowel Disease.