Most people new to a plant-based diet will have already heard concerns about getting enough B12. The recommended daily allowance for adults is 2.4 mcg daily, but it’s essential that ALL vegans supplement.
What does B12 do? B12 is involved in helping create DNA and red blood cells, producing energy, and contributing to immune and nervous system functioning.
Are vegans the only ones at risk of deficiency? No! According to the NIH, up to 15% of the population may be deficient. Among those most at risk include older adults with low stomach acid, individuals on acid-suppressing medications, people with GI disorders such as Celiac or Crohn’s, or those who have had bowel surgeries.
Countless medications have been found to lower the amount of B12 available to the body in some way, including: valproic acid, decadron, diuril, dexamethasone, colchicine, erythromycin, metformin, hydrocortisone, prednisone, proton-pump inhibitors (Prilosec, Prevacid, pantoprazole, Nexium), H2 blockers (Pepcid, Zantac), anticonvulsants, birth control pills, and aminosalicylic acid.
What signs and symptoms may result from a deficiency? There are many nonspecific signs and symptoms including anemia, depression, fatigue, memory loss, neuropathy, and tingling in the extremities.
Should I ask my doctor to test for it? Serum B12 is not really a great marker of B12 status because “concentrations can be maintained at the expense of tissues, a person may exhibit normal serum concentrations but have low tissue concentrations” (Advanced Nutrition and Human Metabolism). A better marker is methylmalonic acid (MMA), which, if elevated, suggests a B12 deficiency, because B12 is needed to convert it into another substance. If there’s not enough B12, methylmalonic acid will build up. MMA can be measured either in blood or urine. Homocystine is another substance that will also be elevated if B12 is insufficient, but it’s not specific for B12 and can be elevated for other reasons. An elevated mean cell volume (MCV) may also be found, indicating that the volume of your blood cells is larger than it should be; though again, it’s not specific for B12.
Did you know? Meat eaters will often use the necessity of B12 supplementation as an argument against veganism, but most don’t realize that the animals they eat are being heavily supplemented, and not just with B12! Swineweb says “Because of the variability of vitamins in natural swine feedstuffs and the relatively low cost of commercial vitamins, it is recommended that producers provide the following vitamins completely from the vitamin premix and disregard amounts in the feed. These are vitamin A, D, E, K, riboflavin, niacin, pantothenic acid, choline and B12.” And on minerals: “Usually, a commercial mineral supplement will meet the needs of most classes of cattle.”
Bottom line: Take a B12 supplement daily, at least 50 mcg. It’s cheap. Symptoms of deficiency are vague. Testing can be inconclusive.
Sources and Additional Reading: Consumer Lab; University of Missouri Extension; Academy of Nutrition and Dietetics
Gropper, S.S. and Smith, J.L. (2018). Advanced Nutrition and Human Metabolism. Boston, MA: Cengage.