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VITAMIN B12 BREAKTHROUGH
BY T
COLIN CAMPBELL PHD
Of all the
nutritional concerns that can plague vegetarians - and especially
complete vegetarians or vegans - I doubt any is more daunting than
the specter of vitamin B12 deficiency. This is especially so because
conventional wisdom has it that this essential vitamin is virtually
unavailable from plant foods.
Because I have often wondered how valid this thinking is, I've asked
myself why, if the health benefits of a plant-based diet are as
comprehensive as contemporary research suggests - meaning that
Nature did the packaging for us during our evolution and that a
plant-based diet is our natural diet - then why did she leave out
this one very important piece of the puzzle?
Having paid attention
to the research literature and having questioned clinicians who
treat vegan patients, I've reached the following somewhat unorthodox
conclusions and observations:
1. Contrary to the most recent U.S. Dietary Guidelines, B12 can be
found in plants.
2. Organically grown plants contain higher levels of B12 than plants
grown non-organically with chemical fertilizers.
3. Plant roots are able to absorb certain vitamins produced by soil
microorganisms, thus suggesting that plants grown in healthy soil,
full of microflora and microfauna, are more nutritious.
4. Vegans - and anyone else - should be able to obtain B12 by
consuming organically grown produce.
5. Evidence that plants obtain vitamins from the soil has been
available for several decades.
To understand what has brought me to these conclusions, let's ask
three essential questions: (1) Are vegans really at greater risk of
B12 deficiency? (2) Does a vegan diet provide all the B12 that we
need? (3) Assuming that there is at least a good chance that we
evolved on this type of diet, how did we get our B12?
Are vegans really at greater risk of B12 deficiency? Some evidence
says yes; some invites skepticism. Clearly, vegans do generally have
lower blood concentrations of B12. A number of studies have shown
this.
But these low concentrations mean little unless there is a
higher incidence of the accompanying blood (megaloblastic anemia)
and nerve (parathesia) disorders, for which there seems to be little
or no evidence. What should be acknowledged is that the
concentrations of other blood factors, such as cholesterol, also are
very different among vegans, and for very good health reasons at
that. Why should we expect the lower B12 levels to be an exception?
A look at the B12 Biases
I must say that I feel some of the confusion surrounding this issue
is due to the biases of the early B12 researchers who, over the
years, made their beliefs very clear that vegetarianism and any
other alternative approach to good ol' Western nutrition and
medicine bordered on health fraud. Yet one of the more renowned of
these investigators, Victor Herbert, reported that "inadequate
absorption [in the digestive tract] accounts for more than 95% of
the vitamin B12 deficiency cases seen in the United States."
The
strong implication here is that the real problem in these cases is
not due to an insufficient intake of B12 brought on by a vegan diet
but that something is wrong with the so-called "intrinsic factor"
which is secreted in the stomach and which is required for B12
absorption.
Acknowledging this possibility, let's move on to our second
question: Does a vegan diet provide all the B12 that we need? To
consider this question, we must keep in mind the prevailing view
that B12 is only found in animal-based foods.
It's worth noting this
point has been so prominent that the latest USDA dietary guidelines,
while allowing for the possibility that vegetarian diets may be
reasonably healthful, nonetheless admonish vegans to "supplement
their diets with a source of this vitamin." According to the Victor
Herbert position, "There is no active vitamin B12 in anything that
grows out of the ground; storage is found only in animal products
where it is ubiquitous and where it is ultimately derived from
bacteria."
He also states that vegans thus can get adequate B12
from their food only if it is fertilized with human waste, or if
they "ingest some of their own feces" or fail to observe hygienic
practices.3 What a prospect Herbert and the USDA folks have given to
the poor vegans!
I have naturally found this view to be highly constrained and,
indeed, illogical, especially if one assumes the strong possibility
that humans survived on a plant-based diet in our evolutionary past.
I do believe there is overwhelming evidence that this is so even
though it has not yet been scientifically proven.
Please understand
that I say this approach is not better or worse than that of Herbert
and the USDA, I'm simply saying it's worth serious consideration.
The B12 Breakthrough
So, on to my third question, based on the assumption that we did
evolve on a plant-based diet, and then asking, how did we get our
B12? To begin, let's examine an exciting new research paper from
Switzerland that was recently brought to my attention by my
colleague, Dr. Jeffrey Gates.4 (Please see related story). Dr.
Mozafar, the investigator, wanted to know if plants fertilized with
organic matter (cow dung in this case) rather than those grown in
control soils might acquire higher levels of B12.
He was relying on
a considerable amount of older research going back to 1926. Plants
grown in soil fertilized with organic matter contained more of some
B vitamins than plants grown in chemically fertilized soil, thus
yielding plant products better able to sustain growth in
experimental animals. Mozafar hypothesized that B12 produced by soil
microorganisms might be absorbed through the roots into the plant
itself.
He investigated the question in a couple of ways. First, he showed
for soybeans, barley and spinach - his three test plants - that
those grown on soil fertilized with cow dung showed substantially
higher levels of B12 than those grown without cow dung, the
increases for barley and spinach being statistically significant.
Then he examined the B12 content of soils that had been routinely
fertilized over the previous 16 years either with inorganic or with
a mixture of organic plus inorganic fertilizers, and found that
those receiving organic fertilizer had significantly higher levels
of B12.
Putting the Nail in the Coffin
These results not only confirm earlier results concerning other B
vitamins, but they seem to put the nail in the coffin of the
Herbert-USDA hypothesis, namely that plants do not contain B12. They
certainly do contain B12, and they contain even more of it when they
are grown organically.
Having said all this, I am still left with
two questions: (1) Would other chemicals capable of killing soil microflora (pesticides, herbicides) have an effect similar to
chemical fertilizers? and (2) How long will it take for our society
to acknowledge the overall health value of plant-based diets, thus
altering the cultural bias that leads Herbert and the USDA to
"discover" problems such as that of B12 deficiency? I can say with
some confidence that time will tell quite a different story than the
one we've been hearing.
References
1 Herbert, V. Recommended dietary intakes (RDI) of vitamin B12 in
humans. American Journal of Clinical Nutrition, 45:671º678, 1987.
2 United States Department of Agriculture, and United States
Department of Health and Human Services. Dietary Guidelines for
Americans, Fourth Edition, p. 43. Washington, D.C.:1995.
3 Herbert, V. Vitamin B12 : plant sources, requirements, and assay.
American Journal of Clinical Nutrition, 48:852º858, 1988.
4 Mozafar, A. Enrichment of some B-vitamins in plants with
application of organic fertilizers. Plant and Soil, 167:305º311,
1994
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