Summary
Dr. Michael Greger covers the healthiest food sources of vitamin B12 for anyone eating a plant-based diet. He recommends either taking 50 micrograms of B12 daily or a once-weekly dose of 2,000 micrograms as the simplest and cheapest approach. For those preferring whole foods, he breaks down the B12 content of various nutritional yeast brands, finding that Bragg's is the most potent option currently available. The episode explains the confusing Daily Value labeling system for B12 and warns that algae products like spirulina not only fail to provide usable B12 for humans but may contain B12 analogues that block absorption of real B12. He notes that anyone over 65 should skip food sources and go straight to high-dose supplements, with separate recommendations for pregnancy and childhood.
Key Points
- Recommended B12 supplementation: 50 mcg daily or 2,000 mcg once weekly
- Three servings of B12-fortified foods per day can meet requirements without supplements
- Bragg's nutritional yeast is the most potent B12-fortified brand (563% DV per tablespoon)
- Spirulina and algae products do NOT provide usable B12 and may contain blocking analogues
- The Daily Value for B12 was changed from 6 to 2.4 mcg in 2020, adding confusion to labels
- Anyone over 65 should use high-dose B12 supplements rather than relying on food sources
- Not all nutritional yeast brands are B12-fortified — always check the label
Key Moments
B12 supplement dosing recommendations for plant-based diets
The simplest and cheapest approach to B12 is either 50 micrograms daily or 2,000 micrograms once weekly. Without supplements, three daily servings of B12-fortified foods each containing at least 190% Daily Value are needed.
"A regular, reliable source of vitamin B12 is critical for anyone eating a plant-based diet, either vitamin B12 supplements or vitamin B12 fortified foods."
Spirulina B12 analogues can block real B12 absorption
Algae products like spirulina do not contain usable B12 for humans and may actually contain look-alike molecules that block absorption of real B12, making them counterproductive for addressing deficiency.
"Not only do they not actually contain B12 that's useable for humans, it's even worse than that. They may contain B12 analogues, look-alike molecules that can even block your absorption of real B12."
