Vitamin
B12 Deficiency—the Meat-eaters’ Last
Stand
Defending eating
habits seems to be a primal instinct
for people. These days Westerners
are running out of excuses for their
gluttony.
Well-read people no longer believe
meat is necessary to meet our
protein needs or
that milk is the favored source of
calcium. With the
crumbling of these two time-honored
battle fronts the vitamin B12 issue
has become the trendy topic whenever
a strict vegetarian (vegan) diet is
discussed. Since the usual
dietary source of vitamin B12 for
omnivores is the flesh of other
animals, the obvious conclusion is
that those who choose to avoid
eating meat are destined to become
B12 deficient. There is a grain of
truth in this concern, but in
reality an otherwise healthy strict
vegetarian’s risk of developing a
disease from B12 deficiency by
following a sensible diet is
extremely rare—less than one chance
in a million.
I knew forty years
ago that vitamin B12 would become
the last bastion for meat- and
dairy-lovers (and the industries
that profit from them), because this
is the only criticism with any merit
that could be lodged against the
McDougall Diet. In order to avoid
that condemnation and the small risk
of harming anyone, I have
recommended and printed in the
beginning of my books and DVDs the
following advice:
If you follow
the McDougall Diet for more
than 3 years, or if you are
pregnant or nursing, then
take a minimum of 5
micrograms of supplemental
vitamin B12 each day.
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Avoid B12 Deficiency;
Get Heart Disease and Cancer
Vitamin B12 is
involved in the metabolism of all
cells in the body; but the effects
of deficiencies are first seen in
the blood and then the nervous
system. An anemia, called
megaloblastic anemia, because it is
characterized by large red blood
cells, is a common manifestation of
deficiency. The low red blood cell
count is very well tolerated by the
patient even when severe, and is
always cured by the taking of small
amounts of B12. Mild problems with
the nervous system characterized by
numbness and tingling in the hands
and feet also develop. These
sensations are reversible in early
stages; however, damage to the
nervous system can become much more
severe and irreversible after
prolonged deficiency.
Take a moment to
compare the possible consequences of
your dietary decisions. You could
choose to eat lots of B12-rich
animal foods and avoid the
one-in-a-million chance of
developing a reversible anemia
and/or even less common, damage to
your nervous system. However, this
decision puts you at a one-in-two
chance of dying prematurely from a
heart attack or stroke; a
one-in-seven chance of breast cancer
or a one-in-six chance of prostate
cancer. The same thinking results
in obesity, diabetes, osteoporosis,
constipation, indigestion, and
arthritis. All these conditions
caused by a B12-sufficient diet are
found in the people you live and
work with daily. How many vegans
have you met with B12 deficiency
anemia or nervous system damage? I
bet not one! Furthermore, you have
never even heard of such a problem
unless you have read the
attention-seeking headlines of
newspapers or medical journals.
Sensationalism
Surrounds B12-Deficient Vegetarians
Rare cases of B-12
deficiency suspected to be caused by
following a vegetarian diet make
media-selling banners, because
“people love to hear good news about
their bad habits.” However, in
depth research reveals that many of
these “vegetarians” also suffer from
generalized malnutrition—not just
isolated B12 deficiency from a diet
based on plant foods. For example,
the March 23, 2000 issue of the New
England Journal of Medicine
published a letter (not a scientific
article) with the provocative title,
“Blindness in a Strict Vegan.”1
The letter described a 33-year old
man who was found to have severe
loss of vision (bilateral optic
neuropathy). He had started a strict
vegetarian diet at age 20. Tests
showed he suffered from deficiencies
of vitamins A, C, D, E, B1, B12 and
folic acid, as well as zinc and
selenium. All combined, these
deficiencies clearly indicate severe
malnutrition. B12 injections
corrected his anemia, but not his
visual loss.
Do you see the
disconnection between the case
history and the headlines?
Starches, vegetables, and fruits are
very rich sources of folic acid and
vitamin C (as well as A, E, B1, zinc
and selenium). His malnourished
condition most likely was caused by
an intestinal disease and/or an
unhealthy “vegetarian” diet.2
The headlines published worldwide
that followed this letter reassured
meat- and dairy-lovers that becoming
a vegetarian was an unwise
decision. Examination of many
reported cases of B12 deficiency
connected to a vegetarian diet in
both children and adults reveals
similar confounding factors.1-6
The patients may have subtle
malabsorption and often come from
conditions of poverty and/or live an
eccentric lifestyle—their health
problems are not simply due to
avoiding animal foods. However, I
do believe there are very rare
patients with diseases due to lack
of B12 from following a strict
vegetarian diet for years—while
others have disagreed with me and
believe that all cases have
confounding factors.7
Germs for Good Health
Although vitamin B12
is found in animal foods it is not
synthesized by plants or animals.
Only bacteria make biologically
active vitamin B12—animal tissues
store “bacteria-synthesized B12,”
which can then be passed along the
food chain by animals eating another
animal’s tissues. Ruminants (like
cows, goats, sheep, giraffes,
llamas, buffalo, and deer) are
unique in that bacteria in their
rumens (stomachs) synthesize vitamin
B12, which is then passed down and
absorbed by their small intestines.
Lions and tigers get their B12 from
eating these grazers.
The human gut also
contains B12-synthesizing bacteria,
living from the mouth to the anus.8
The presence of these bacteria is an
important reason that disease from
vitamin B12 deficiency occurs very
rarely in people, even those who
have been strict vegetarians
(vegans) all of their lives. The
colon contains the greatest number
of bacteria (4 trillion/cc of
feces), and here most of our
intestinal B12 is produced.
However, because B12 is absorbed in
the ileum, which lies upstream of
the colon, this plentiful source of
B12 is not immediately available for
absorption—unless people eat feces
(don’t gasp). Feces of cows,
chickens, sheep and people contain
large amounts of active B12. Until
recently most people lived in close
contact with their farm animals, and
all people consumed B12 left as
residues by bacteria living on their
un-sanitized vegetable foods.
Why would a
plant-food-based diet, heralded as a
preventative and cure for our most
common chronic diseases be deficient
in any way? Such a diet appears to
be the proper, intended, diet for
humans, except for this one
blemish. The reason for this
apparent inconsistency is we now
live in unnatural conditions—our
surroundings have been sanitized by
fanatical washing, powerful
cleansers, antiseptics, and
antibiotics. Since the germ theory
of disease was developed by Louis
Pasteur in 1877 our society has
waged an all-out war on these tiny
creatures—most of them extremely
beneficial with only a very few
acting as pathogens. The rare case
of B12 deficiency may be one
important consequence of too much
cleanliness.
Efficiency Is the
Other Reason Deficiency Is Rare
The human body has
evolved with highly efficient and
unique mechanisms to absorb,
utilize, and conserve this vitamin.
Our daily requirement is less than 3
micrograms a day—one microgram is
one-millionth of a gram (1/1,000,000
gram).9 Which means, by
design, people are expected to be
exposed to only miniscule amounts of
this essential nutrient.
Vitamin B12 is the
only nutrient that requires a
cofactor for efficient absorption.
The cells of the stomach produce a
substance, called intrinsic factor,
which combines—after the acidic
digestion of the food in the
stomach—with the B12 released from
food. This “intrinsic factor-B12
complex” then travels to the end of
the small intestine (the ileum)
where it is actively absorbed.
There is a second,
much less efficient process, called
“the passive absorption of B12”
which also occurs in the intestine.
This mechanism does not use
intrinsic factor and as a result it
is 1/1000 as efficient. But by
consuming very large doses of oral
B12, passive absorption will correct
B12 deficiency even for patients
with diseases of the stomach and
small intestine.
On average, for
someone raised on the Western diet,
about 2 to 5 milligrams of B12 are
stored, mostly in the liver. This
means most people have at least a
three year reserve of this vital
nutrient. Conservation of B12 by the
body boosts the time this supply
lasts by 10-fold. After excretion
through the bile into the intestines
most of the B12 is reabsorbed by the
ileum for future use. As a result of
this recirculation it actually
takes, on average, 20 to 30 years to
become deficient after becoming a
strict vegan. That is if no vitamin
B12 were consumed—which is
impossible, even on a strict vegan
diet, because of bacterial sources
of B12 from the person’s bowel,
contaminated vegetable foods, and
the environment.
There is evidence
that suggests that during pregnancy
and nursing a mother is more
dependent on B12 from her diet,
because B12 stored in the woman’s
body is less available for the baby.10
Therefore, during these
important times, B12 supplementation
should be used by a vegan mother.
Biochemical Changes
Occur with Low B12
Blood levels of B12
can be measured directly in the
blood and are a means to help
diagnose deficiency. Values above
150 pg/ml (picograms per milliliter)
are considered normal, and levels
below 80 pg/ml represent unequivocal
B12 deficiency.11
Within the body,
biochemical reactions require B12. A
deficiency can cause an interruption
of normal metabolism and result in
the accumulation of substances like
methylmalonic acid and the amino
acid, homocysteine. Tests showing
increases in these metabolic
products are used to diagnose “early
B12 deficiency”—before any actual
disease occurs.
Elevated homocysteine
has been associated with an
increased risk of common Western
diseases (heart attacks, strokes,
etc.). However, this amino acid
itself does not cause disease—it
serves as a marker for identifying
people who consume large amounts of
animal foods. Eating meat, poultry,
fish, and cheese raises levels of
homocysteine—as well as these same
foods making people fat and sick.
Efforts to lower homocysteine with
supplements of folic acid and/or B12
have produced no reduction in heart
disease or stroke12—and
in fact the use of folic acid
supplements increases the risk of
cancer, heart disease, and overall
death.13
The long-term
consequences of B-12 supplementation
are unknown; so far this vitamin
appears to be non-toxic and
beneficial. As a result, I currently
have no hesitation recommending
supplements to strict vegetarians in
order to prevent the rare chance of
a deficiency occuring.
Intestinal Diseases,
Not Dietary Deficiency, Cause Most
B12 Problems
Almost all cases of
vitamin B12 deficiency seen in
patients today and in the past are
due to diseases of the intestine,
and are not due to a lack of B12 in
their diet. Damage to the stomach
(parietal cells) usually from an
autoimmune disease or surgery halts
the production of intrinsic factor.
Damage to the ileum, preventing
reabsorption and interrupting
recirculation, causes the loss of
B12. Over a period of 3 to 6 years
the body’s stores of vitamin B12 are
depleted. The disease that results
is called pernicious anemia. (The
word pernicious refers to a tendency
to cause death or serious injury.)
Prior to the development of a
treatment with liver extracts in
1926 this condition was fatal.14-15
The History
of B12 Deficiency from
Pernicious Anemia (PA)14-15
1824—A fatal
form of anemia associated
with stomach degeneration
was first described by J.S.
Combe of Edinburgh.
1860—Austin
Flint recognized the
nutritional basis of this
anemia and the degeneration
of the stomach in this
disease.
1872—Biermer,
in Switzerland, coined the
concept of pernicious anemia
(PA) based on the inevitably
fatal outcome of this
disorder.
1880’s—Ehrlich added that
patients with this anemia
had giant peripheral blood
cells, so called
megaloblasts.
1887—Lichtheim
describes an association of
PA and spinal cord lesions.
1921—Levine
and Ladd reported that no
stomach acid was found in
patients with PA.
1925—William
Castle fed cooked ground
beef to healthy young men
and one hour later, removed
the gastric juice which
contained partly digested
beef, and placed it in the
stomach of patients with
pernicious anemia. As a
control, he gave ground beef
without gastric juice to
another group of patients.
The experimental group
responded with the
production of new blood
cells, but the control group
did not. He postulated that
some unknown, but essential,
interaction between beef
muscle as an extrinsic
factor and normal human
gastric juice as an
intrinsic factor was
required.
1926—Two
American physicians, Minot
and Murphy, described a raw
liver diet (liver therapy)
that cured PA in the Journal
of the American Medical
Association. They received
the Nobel Prize in
Physiology and Medicine in
1934 for their work.
1941—Folic
acid received its name
following its isolation from
spinach (from the Latin
‘folium’ meaning leaf).
Folic acid deficiency causes
megaloblastic anemia, but
not nervous system damage.
1945—Folic
acid was synthesized and
found to be effective in
treating all types of
megaloblastic anemia, but
especially those that proved
refractory to liver
preparations such as the
megaloblastic anemia of
sprue, celiac disease,
pregnancy and malnutrition.
1948—Two
independent teams in the
United States and England
isolated the mysterious
extrinsic factor, vitamin
B12, in crystalline form.
1955—Dorothy
Crowfoot Hodgkin, a British
chemist, elucidated the
unique and complex chemical
structure of this large
molecule, in its
cyanocobalamin form, using
X-Ray crystallography. She
was awarded the Nobel Prize
for Chemistry in 1964.
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Sources of Vitamin
B12
As little as 0.3 to
0.65 micrograms per day of vitamin
B12 has cured people of
megaloblastic anemia;9
however, to add an extra margin of
safety I have recommended a higher
dosage of 5 micrograms per day. You
may be surprised to discover that
you cannot purchase these tiny
dosages. Supplements sold contain
500 to 5000 micrograms per pill.
These exaggerated concentrations
will correct by passive absorption
B12 deficiency caused by disease of
the intestine.16-17
Everyone else is being overdosed by
a factor of 1000. If you are an
otherwise healthy vegan and are
using typical dosages of B12 (500
micrograms or more per pill), a
weekly dose of this vitamin will be
more than sufficient.
You will often find
B12 sold under its proper name.
Because vitamin B12 contains one
molecule of the mineral cobalt, the
scientific name is Cobalamin. As a
food additive and a supplement pill,
vitamin B12 is usually found in the
form cyanocobalamin. The
effectiveness of this “cyanide
complex” for treating neurologic
problems has been questioned;
therefore, other forms, such as
methylcobalamin and hydroxycobalamin
may be better choices for the
prevention and treatment of
B12-related conditions.18
Choosing a bioactive
form of B12 is important. There are
many B12-like substances called
analogues found in food supplements,
such as spirulina and other
algae—these are ineffective and
should not be relied upon.19
Foods fermented by bacteria, such as
tempeh, and miso; as well as sea
vegetables (nori), have been
recommended as sources of B12. Miso
and tempeh do not contain B12.20
Nori—the dried green and purple
lavers commonly used to make
sushi—has been tested and found to
have substantial amounts of active
vitamin B12 and has been recommended
a “most excellent source of vitamin
B12 among edible seaweeds,
especially for strict vegetarians.”20,21
(Nori obtains its B12 from symbiotic
bacteria that live on it.22)
However, there is still some
uncertainty about nori as a reliable
B12 source; therefore, I suggest if
you do choose this seaweed that you
should monitor your B12 levels by
blood tests now, and if adequate,
every 3 years.
In order to minimize
your risk of any health problems, I
recommend you and your family follow
a diet based on starches,
vegetables, and fruits. To avoid
the extremely rare chance of
becoming a national headline, add a
reliable B12 supplement. By making
this addition to a healthy diet you
can’t go wrong, nor will you suffer
from any justifiable criticism of
your McDougall Diet delivered by
well-meaning family and friends.
References:
1) Milea D, Cassoux
N, LeHoang P. Blindness in a strict
vegan. N Engl J Med. 2000 Mar
23;342(12):897-8.
2) Lavine JB.
Blindness in a vegan. N Engl J
Med. 2000 Aug 24;343(8):585;
3) Carmel R.
Nutritional vitamin-B12 deficiency.
Possible contributory role of subtle
vitamin-B12 malabsorption. Ann
Intern Med. 1978
May;88(5):647-9.
4) No authors.
Vegetarian diet and vitamin B12
deficiency. Nutr Rev. 1978
Aug;36(8):243-4.
5) Avci Z, Turul T,
Aysun S, Unal I. Involuntary
movements and magnetic resonance
imaging findings in infantile
cobalamine (vitamin B12) deficiency.
Pediatrics. 2003 Sep;112(3 Pt
1):684-6.
6) February 2003
McDougall Newsletter: Vegan Diet
Damages Baby’s Brain –
Sensationalism!
http://www.nealhendrickson.com/mcdougall/030200puVeganDietDamages.htm
7) Immerman AM.
Vitamin B12 status on a vegetarian
diet. A clinical review. World
Rev Nutr Diet. 1981;37:38-54.
8) Albert MJ, Mathan
VI, Baker SJ. Vitamin B12 synthesis
by human small intestinal bacteria.
Nature. 1980 Feb
21;283(5749):781-2.
9) Stabler SP, Allen
RH. Vitamin B12 deficiency as a
worldwide problem. Annu Rev Nutr.
2004;24:299-326.
10) Koebnick C,
Hoffmann I, Dagnelie PC, Heins UA,
Wickramasinghe SN, Ratnayaka ID,
Gruendel S, Lindemans J, Long-term
ovo-lacto vegetarian diet impairs
vitamin B-12 status in pregnant
women. J Nutr. 2004
Dec;134(12):3319-26.
11) Ting RZ, Szeto
CC, Chan MH, Ma KK, Chow KM. Risk
factors of vitamin B(12) deficiency
in patients receiving metformin.
Arch Intern Med. 2006 Oct
9;166(18):1975-9.
12 Wierzbicki AS.
Homocysteine and cardiovascular
disease: a review of the evidence.
Diab Vasc Dis Res. 2007
Jun;4(2):143-50.
13. McDougall
Newsletter. Folic Acid Supplements
are a Health Hazard
October 2005
https://www.drmcdougall.com/misc/2005nl/oct/051000folic.htm
14) Chanarin I.
Historical review: a history of
pernicious anaemia. Br J Haematol.
2000 Nov;111(2):407-15.
15) Okuda K.
Discovery of vitamin B12 in the
liver and its absorption factor in
the stomach: a historical review.
J Gastroenterol Hepatol. 1999
Apr;14(4):301-8.
16) Butler CC, Vidal-Alaball
J, Cannings-John R, McCaddon A, Hood
K, Papaioannou A, Mcdowell I,
Goringe A.Oral vitamin B12 versus
intramuscular vitamin B12 for
vitamin B12 deficiency: a systematic
review of randomized controlled
trials. Fam Pract. 2006
Jun;23(3):279-85.
17) Vidal-Alaball J,
Butler CC, Cannings-John R, Goringe
A, Hood K, McCaddon A, McDowell I,
Papaioannou A. Oral vitamin B12
versus intramuscular vitamin B12 for
vitamin B12 deficiency. Cochrane
Database Syst Rev. 2005 Jul
20;(3):CD004655.
18) Freeman AG.
Hydroxocobalamin versus
cyanocobalamin. J R Soc Med.
1996 Nov;89(11):659.
19) Watanabe F,
Takenaka S, Kittaka-Katsura H, Ebara
S, Miyamoto E. Characterization and
bioavailability of vitamin
B12-compounds from edible algae. J
Nutr Sci Vitaminol (Tokyo). 2002
Oct;48(5):325-31.
20) Watanabe F.
Vitamin B12 sources and
bioavailability.
Exp Biol Med (Maywood).
2007 Nov;232(10):1266-74.
21) Watanabe F,
Takenaka S, Katsura H, Masumder SA,
Abe K, Tamura Y, Nakano Y. Dried
green and purple lavers (Nori)
contain substantial amounts of
biologically active vitamin B(12)
but less of dietary iodine relative
to other edible seaweeds. J Agric
Food Chem. 1999
Jun;47(6):2341-3.
22) Croft MT,
Lawrence AD, Raux-Deery E, Warren MJ,
Smith AG. Algae acquire vitamin B12
through a symbiotic relationship
with bacteria. Nature. 2005
Nov 3;438(7064):90-3. |