The results of vitamin B12 deficiency can be devastating. Learn more in our easy-to-understand videos on the latest research.
Vitamin B12 is not made by plants or animals but by microbes that blanket the earth. In today’s sanitized, modern world, the water supply is commonly chlorinated to kill off any bacteria. So, while we don’t get much B12 in the water anymore, we don’t get much cholera, either, which is a good thing!
A regular, reliable source of vitamin B12 is critical for anyone eating a plant-based diet. Though deficiency for those starting out with adequate stores may take years to develop, the results of B12 deficiency can be devastating, with cases reported of paralysis, psychosis, blindness, and even death. Newborn infants of mothers who eat a plant-based diet and who fail to supplement may develop deficiency much more rapidly with disastrous results. Getting enough vitamin B12 is absolutely nonnegotiable for those centering their diets around plant-based foods.
For adults under age 65, the easiest way to get B12 is to take at least one 2,000 mcg supplement each week or a daily dose of 50 mcg. Note that these doses are specific to cyanocobalamin, the preferred supplemental form of vitamin B12, as there is insufficient evidence to support the efficacy of the other forms, like methylcobalamin.
As we age, our ability to absorb vitamin B12 may decline. For those over 65 who eat plant-based diets, the supplementation should probably be increased up to 1,000 mcg of cyanocobalamin each day.
Instead of taking B12 supplements, it is possible to get sufficient amounts from B12-fortified foods, but we would have to eat three servings a day of foods each providing at least 190 percent of the Daily Value (on the Nutrition Facts label), with each serving eaten at least four to six hours after the last (based on the new labeling mandated to start January 1, 2020—the target is 4.5 mcg three times a day). For B12-fortified nutritional yeast, for example, two teaspoons three times a day may suffice. For most of us, though, it would probably be cheaper and more convenient to just take a supplement. Our fellow great apes get all the B12 they need eating bugs, dirt, and feces, but I’d suggest supplements instead!
The information on this page has been compiled from Dr. Greger’s research. Sources for each video listed can be found by going to the video’s page and clicking on the Sources Cited tab. References may also be found at the back of his books.
Image Credit: NatchaS / Thinkstock. This image has been modified.
Popular Videos for Vitamin B12
All Videos for Vitamin B12
Are Vegans at Risk for Iodine Deficiency?
Most plant-based milks are not fortified with iodine.
Do Vitamin B12 Supplements Cause Bone Fractures and Lung Cancer?
What do randomized controlled trials of high-dose daily vitamin B12 supplementation show about the effects on cancer risk, death, and longevity?
Do Vitamin B12 Supplements Cause Acne?
Acne can be triggered in one in ten people who get vitamin B12 injections.
The Best Type of Vitamin B12: Cyanocobalamin or Methylcobalamin?
For prevention and treatment of vitamin B12 deficiency, cyanocobalamin in chewable, sublingual, or liquid forms (rather than in a multivitamin) is best under most circumstances.
The Optimal Vitamin B12 Dosage for Kids, Pregnancy, and Seniors
At age 50, everyone, regardless of diet should start supplementing with B12-fortified foods or supplements but over age 65 only high-dose daily supplements may suffice.
The Healthiest Food Sources of Vitamin B12
What are the best green-light (whole food plant-based) sources of vitamin B12?
The Optimal Vitamin B12 Dosage for Adults
Why the current Recommended Daily Allowance for vitamin B12 may be insufficient.
The Symptoms of Vitamin B12 Deficiency
B12 deficiency is known as “The Great Masquerader.”
The Efficacy and Safety of Creatine for High Homocysteine
Those on a healthy plant-based diet with elevated homocysteine levels despite taking sufficient vitamin B12 may want to consider taking a gram a day of contaminant-free creatine.
Should Vegetarians Take Creatine to Normalize Homocysteine?
What are the consequences of having to make your own creatine rather than relying on dietary sources?
How to Test for Functional Vitamin B12 Deficiency
Many doctors mistakenly rely on serum B12 levels in the blood to test for vitamin B12 deficiency.
Vegetarians and Stroke Risk Factors—Vitamin B12 & Homocysteine?
Not taking B12 supplements or regularly eating B12 fortified foods may explain the higher stroke risk found among vegetarians.