Is it true we can actually absorb some B12 from our own microbiome? Is duckweed, nori, chlorella, or spirulina a reliable source of vitamin B12?
This is the third video in a five-part series on vitamin B12. If you missed the previous two, check out How Long Does It Take to Become Vitamin B12-Deficient and What Are the Symptoms? (https://nutritionfacts.org/video/how-long-does-It-take-to-become-vitamin-b12-deficient-and-what-are-the-symptoms) and The Best Way to Test for Vitamin B12 Deficiency (https://nutritionfacts.org/video/the-best-way-to-test-for-vitamin-b12-deficiency). Stay tuned for How Much Vitamin B12 Do We Need Each Day? (https://nutritionfacts.org/video/how-much-vitamin-b12-do-we-need-each-day) and Are Large Weekly Doses of Vitamin B12 Safe? (https://nutritionfacts.org/video/are-large-weekly-doses-of-vitamin-b12-safe).
For more on vitamin B12, check out the topic page (https://nutritionfacts.org/topics/vitamin-b12/).
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“The Best Source of Vitamin B12:
Supplements, Shots, or Fortified Foods?” To treat vitamin B12 deficiency, intramuscular injections, oral pills,
or sublingual lozenges can similarly
effectively increase the level of vitamin B12
at sufficient doses, but this is based
on blood level targets rather than
assessing clinical outcomes, in terms of symptom improvement. So, some believe
that at least initially, injected B12 should be
the first-choice treatment for patients
with severe B12 deficiency, though even
with the best treatment, neurological symptoms
may take several months or even years to resolve,
and may never get better. So, it’s better to prevent
deficiency in the first place. B12 isn’t made
by plants or animals, but rather by bacteria, so, feces are
a good source of vitamin B12. That’s one of the ways
our fellow great apes, like gorillas, get B12. Evidently dining on dung
was seen to be more common after wet weather, though,
leading to the suggestion that besides
its nutritional importance, it may be just that they want
something warm to nibble on at the end of a long, cold rain. Thankfully, since the advent
of modern sanitation, bacteria and feces are, happily, no longer reliable sources
of vitamin B12 for humans. A large proportion
of the bacteria in our gut do make B12, though, but it’s always
been thought to be produced too far down to be absorbed. How do we know? Because if you squirt
radioactively-labeled B12 into people’s rectums, they don’t really seem
to absorb it. But the human colon
is about five feet long (1.5 m) and it was just squirted in
about a foot (30 cm). What about higher up? No B12 uptake
from the human colon had ever been previously
described or considered, until now. B12 was squirted
via colonoscopy all the way up
to the beginning of the colon, and, dun dun dun dun, B12 is absorbed
in the human colon. Or at least a little bit was. Now the squirt occurred
just a few inches (5 cm) from the end
of the small intestine, so some of it
may have slipped out and was absorbed there,
even higher up, but presumably the same
could happen with any B12 made by our own microbiome. The researchers suggest that this potential
colonic absorption might help explain
an apparent paradox. There are hundreds of millions
of vegetarians in India, so why don’t we see
more B12 deficiency? Well, vitamin B12 deficiency
is endemic in India with B12 deficiency rates
running as high as 50 to 77%, but maybe the reason
it’s not closer to 100% is because they’re absorbing
a bit from their microbiome. Obviously, though, it’s not
something we can count on. The safest way
to prevent B12 deficiency in plant-based diets is to take
an oral B12 supplement. B12-fortified foods
like certain brands of nutritional yeast or soymilk
are another option, but may only provide
adequate vitamin B12 when consumed
multiple times a day. What about chlorella
and spirulina, which both claim
to contain B12? But actually, up to 90%
of the so-called B12 is pseudo-B12,
B12 analogs that look like B12 but are actually unusable
by our body. It’s outrageous
that manufacturers would advertise real B12
when there may be none. It’s crucial consumers are not
misled by wrong information. What about duckweed,
which also claims to have B12? Sometimes it does, but not because it
or any plant makes it, but because of variable amounts
of bacterial contamination. If you actually disinfect
the plants to reduce the bacteria loads
in duckweed, you end up with little B12. Same with seaweed like nori. Sometimes it’s contaminated
with B12-producing microbes, other times not, and sometimes it has
pseudo-B12 producing bugs. For example, in this study, eating nori actually made
B12 status worse, whereas, in this study, nori made B12 status
mostly better, but even then,
it made B12 status worse in two of the participants. That’s why those eating
unfortified plant-based diets must take B12 supplements. But which kind is best? If you ask ChatGPT, it says methylcobalamin
and adenosylcobalamin are better than cyanocobalamin, but ChatGPT is wrong. (It must have just sucked up all that slimy supplement
company propaganda.) Check out my video
on why cyanocobalamin is best for most people.
