A small but vocal
minority of vegans do claim that B12-fortified foods and supplements
are unnecessary. In criticising this claim, Byrnes is merely repeating
the majority view in the vegan community (www.vegansociety.com/html/info/b12sheet.htm),
but adding his own distinctive spin. The seeds of his counter-mythology
are already being sown with the claim that "every study of vegan
groups has demonstrated low vitamin B12 concentrations in the majority
of individuals". This is incorrect. Studies of vegan groups with
adequate average intakes of B12 from fortified foods or supplements,
such as Haddad (1999), demonstrate excellent average B12 status in
vegans including desirably low homocysteine levels. The claim "vitamin
B12 is only found in animal foods" is also incorrect as the primary
source of B12 is bacteria (no animal synthesises its own B12, all
rely on B12 from bacteria). B12 is found wherever B12-producing bacteria
is not real B12 in plant sources but B12 analogues--they are similar
to true B12, but not exactly the same and because of this they
are not bioavailable. It should be noted here that these B12 analogues
can impair absorption of true vitamin B12 in the body due to competitive
absorption, placing vegans and vegetarians who consume lots of
soy, algae, and yeast at a greater risk for a deficiency.
Had Byrnes limited
himself to claiming that most B12 in the majority of possible plant
sources tested had been found to be inactive analogues, this would
be correct. The exceptions identified include undried nori and pleurochrysis
carterae (a unicellular alga). The suggestion that soy, algae or
yeast increase the risk of B12 deficiency is misleading. Dried nori
contains mostly inactive analogues and has been shown to interfere
with B12 metabolism if eaten in very large quantities (40 g per
day). In normal amounts, however, it causes no problem provided
adequate dietary sources of true B12 are consumed. The same applies
to fermented soy products and yeasts: there is no indication that
their B12 analogues pose any risk to human health. Unfermented soy
products such as soy milk and tofu do not contain significant amounts
vegetarian authorities claim that B12 is produced by certain fermenting
bacteria in the lower intestines. This may be true, but it is
in a form unusable by the body. B12 requires intrinsic factor
from the stomach for proper absorption in the ileum. Since the
bacterial product does not have intrinsic factor bound to it,
it cannot be absorbed.
in the large intestine certainly do produce B12 (along with plenty
of inactive analogues). Many of our primate relatives eat faeces
and may obtain much of their B12 from this source.
is true that Hindu vegans living in certain parts of India do
not suffer from vitamin B12 deficiency. This has led some to conclude
that plant foods do provide this vitamin. This conclusion, however,
is erroneous as many small insects, their feces, eggs, larvae
and/or residue, are left on the plant foods these people consume,
due to non-use of pesticides and inefficient cleaning methods.
This is how these people obtain their vitamin B12. This contention
is borne out by the fact that when vegan Indian Hindus later migrated
to England, they came down with megaloblastic anaemia within a
few years. In England, the food supply is cleaner, and insect
residues are completely removed from plant foods.
This is very
muddled. There are no studies of B12 status in Indian vegans as
veganism is very rare in India. Indian lacto-vegetarians in the
UK show a higher incidence of megaloblastic anaemia than typical
in the UK, due to relatively low dietary intake of B12. However,
the vast majority of Hindu lacto-vegetarians in the UK and in India
never develop symptoms of B12 deficiency.
only reliable and absorbable sources of vitamin B12 are animal
products, especially organ meats and eggs (17). Though present
in lesser amounts than meat and eggs, dairy products do contain
B12. Vegans, therefore, should consider adding dairy products
into their diets. If dairy cannot be tolerated, eggs, preferably
from free-run hens, are a virtual necessity.
In making this
claim, Byrnes is promoting a myth with as little basis as the one
he sets out to criticise and with considerable potential for harm.
B12 from fortified foods or supplements (directly harvested from
bacteria) is at least as reliable and absorbable as B12 from animal
products. In setting the US Dietary Reference Intakes for B12, the
Institute of Medicine (1998) notes: "Because 10 to 30% of older
people may be unable to absorb naturally occurring vitamin B12,
it is advisable for those older than 50 years to meet their RDA
mainly by consuming foods fortified with vitamin B12 or a vitamin
B12-containing supplement." Tucker et al. (2000) present evidence
that fortified foods, supplements and dairy products are more effective
sources of B12 than meat for all age groups. There is therefore
no nutritional reason for vegans to use dairy or eggs as a source
of B12 and this attempt to create an illusory need, which conflicts
with vegan ethics, is contemptible.
vitamin B12 can only be obtained from animal foods is one of the
strongest arguments against veganism being a "natural"
way of human eating. Today, vegans can avoid anemia by taking
supplemental vitamins or fortified foods. If those same people
had lived just a few decades ago, when these products were unavailable,
they would have died.
a false picture of universal dependence on meat and eggs for B12,
Byrnes then draws the conclusion that we are adapted to require
animal products in our diet and that vegan diets are unnatural.
There is no evidence that humans are biologically adapted to require
B12 from animal products, as opposed to any other source of bacteria-generated
B12, so the claim that our need for B12 shows that diets free from
meat, milk and eggs are "unnatural" does not pass square
one. Most large wild primates consume minimal amounts of meat (insufficient
to provide a human with B12) yet have blood B12 levels similar to
non-vegetarian humans. Some primates eat faeces, some deliberately
eat insects and all consume remnants of insects incidentally with
the fruits, leaves and shoots which form the bulk of the diet of
our great ape relatives. All get their B12 from bacteria.
of all persuasions, embrace the benefits of sanitary food preparation
and therefore lose the B12 sources that have sustained our fellow
great apes for millions of years. This "unnatural" choice
is enthusiastically embraced and creates a need for a different
source of bacterial B12 to those satisfying the needs of the other
great apes. Fortified foods and supplements containing the desired
bacterial B12 provide the perfect alternative: no direct harm to
sentient beings, minimal environmental impact and no unhealthy extras
such as saturated fat.
The most distinctive
characteristic of human nature is our exceptional capacity to recreate
our environment in a manner more conducive to our needs. We cook
food, live in houses and wear clothes. None of these are "natural"
in the sense of having been around for a significant part of human
evolution, but all are entirely natural to our species. We manipulate
our environment in many ways to meet our needs and, at our best,
to avoid harm to other humans, animals and the environment. Getting
B12 from fortified foods or supplements is an entirely natural and
commendable choice for humans to make.
In this example,
Byrnes makes some good points, which have been made previously by
many vegetarians and vegans, but he mixes these with inaccurate
observations of his own and spins himself to a completely unjustified
conclusion. Byrnes claims elsewhere (http://www.mercola.com/2000/apr/2/vegetarian_myths.htm)
to have saved two vegans' lives by persuading them to drink milk.
This is the sorry end-point of his myth-making "debunking":
promoting the demonstrably fallacious myth that only animal products
provide reliable and absorbable sources of B12 in order to persuade
people to abandon an ethical and at its best exceedingly healthful
further information on B12, see www.vegansociety.com/html/info/b12sheet.htm
For an outline
of a talk by Stephen Walsh at the World Vegetarian Congress in July
2002 (B12: an essential part of a healthy plant-based diet) see
Haddad et al.
(1999): American Journal of Clinical Nutrition, 1999; 70: 586S-593S,
Dietary intake and biochemical, hematologic, and immune status of
vegans compared with nonvegetarians, Ella H Haddad et al.
Medicine (1998): Dietary Reference Intakes for Thiamin, Riboflavin,
Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin,
and Choline, National Academy Press, 1998 ISBN 0-309-06554-2 (http://books.nap.edu/books/0309065542/html/306.html)
Tucker et al.
(2000): American Journal of Clinical Nutrition, 2000, 71: 514-522,
Plasma vitamin B-12 concentrations relate to intake source in the
Framingham Offspring Study, Katherine L Tucker et al.
My thanks to members of the IVU Science group, particularly Syd
Baumel, Jack Norris and Deborah Pageau, for helpful comments on
earlier drafts of this critique.