Uploaded November 2025 | Updated September 2026, 2 weeks ago
How are the recommended daily and weekly doses of vitamin B12 derived? Why might we need more than the recommended daily dose for B12?
This is the fourth video in a five-part series on vitamin B12. If you missed any of the previous ones, check out:
• How Long Does It Take to Become Vitamin B12-Deficient and What Are the Symptoms? (nutritionfacts.org/video/how-long-does-It-take-to-become-vitamin-b12-deficient-and-what-are-the-symptoms)
• The Best Way to Test for Vitamin B12 Deficiency (nutritionfacts.org/video/the-best-way-to-test-for-vitamin-b12-deficiency)
• The Best Source of Vitamin B12: Supplements, Shots, or Fortified Foods? (nutritionfacts.org/video/the-best-source-of-vitamin-b12-supplements-shots-or-fortified-foods)
Stay tuned for Are Large Weekly Doses of Vitamin B12 Safe? (nutritionfacts.org/video/are-large-weekly-doses-of-vitamin-b12-safe).
For more on vitamin B12, check out the topic page (nutritionfacts.org/topics/vitamin-b12/).
New subscribers to our e-newsletter always receive a free gift. Get yours here: nutritionfacts.org/subscribe/.
Have a question about this video? Leave it in the comment section at nutritionfacts.org/video/how-much-vitamin-b12-do-we-need-each-day and someone on the NutritionFacts.org team will try to answer it.
Want to get a list of links to all the scientific sources used in this video? Click on Sources Cited at nutritionfacts.org/video/how-much-vitamin-b12-do-we-need-each-day. You’ll also find a transcript and acknowledgements for the video, my blog and speaking tour schedule, and an easy way to search (by translated language even) through our videos spanning more than 2,000 health topics.
Thanks for watching. I hope you’ll join in the evidence-based nutrition revolution!
-Michael Greger, MD FACLM
Captions for this video are available in several languages; you can find yours in the video settings. View important information about our translated resources: nutritionfacts.org/translations-info
NutritionFacts.org
• Subscribe: nutritionfacts.org/subscribe
• Donate: nutritionfacts.org/donate
• Podcast : nutritionfacts.org/audio
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How are the recommended daily and weekly doses of vitamin B12 derived? Why might we need more than the recommended daily dose for B12?
This is the fourth video in a five-part series on vitamin B12. If you missed any of the previous ones, check out:
• How Long Does It Take to Become Vitamin B12-Deficient and What Are the Symptoms? (nutritionfacts.org/video/how-long-does-It-take-to-become-vitamin-b12-deficient-and-what-are-the-symptoms)
• The Best Way to Test for Vitamin B12 Deficiency (nutritionfacts.org/video/the-best-way-to-test-for-vitamin-b12-deficiency)
• The Best Source of Vitamin B12: Supplements, Shots, or Fortified Foods? (nutritionfacts.org/video/the-best-source-of-vitamin-b12-supplements-shots-or-fortified-foods)
Stay tuned for Are Large Weekly Doses of Vitamin B12 Safe? (nutritionfacts.org/video/are-large-weekly-doses-of-vitamin-b12-safe).
For more on vitamin B12, check out the topic page (nutritionfacts.org/topics/vitamin-b12/).
New subscribers to our e-newsletter always receive a free gift. Get yours here: nutritionfacts.org/subscribe/.
Have a question about this video? Leave it in the comment section at nutritionfacts.org/video/how-much-vitamin-b12-do-we-need-each-day and someone on the NutritionFacts.org team will try to answer it.
Want to get a list of links to all the scientific sources used in this video? Click on Sources Cited at nutritionfacts.org/video/how-much-vitamin-b12-do-we-need-each-day. You’ll also find a transcript and acknowledgements for the video, my blog and speaking tour schedule, and an easy way to search (by translated language even) through our videos spanning more than 2,000 health topics.
Thanks for watching. I hope you’ll join in the evidence-based nutrition revolution!
-Michael Greger, MD FACLM
Captions for this video are available in several languages; you can find yours in the video settings. View important information about our translated resources: nutritionfacts.org/translations-info
NutritionFacts.org
• Subscribe: nutritionfacts.org/subscribe
• Donate: nutritionfacts.org/donate
• Podcast : nutritionfacts.org/audio
• Books: nutritionfacts.org/books
• Shop: drgreger.org
• Facebook: facebook.com/NutritionFacts.org
• Twitter: twitter.com/nutrition_facts
• Instagram: instagram.com/nutrition_facts_org
