What Every Vegan Should Know About Vitamin B12
Very low B12 intakes can cause anaemia and nervous system damage.
The only reliable vegan sources of B12 are foods fortified with B12 (including some plant milks, some soy products and some breakfast
cereals) and B12 supplements. Vitamin B12, whether in supplements,
fortified foods, or animal products, comes from micro-organisms.
Most vegans consume enough B12 to avoid anaemia and nervous system
damage, but many do not get enough to minimise potential risk of heart
disease or pregnancy complications.
To get the full benefit of a vegan diet, vegans should do one of the following:
- eat fortified foods two or three times a day to get at least three micrograms (μg or mcg) of B12 a day or
- take one B12 supplement daily providing at least 10 micrograms or
- take a weekly B12 supplement providing at least 2000 micrograms.
If relying on fortified foods check the labels carefully to make sure
you are getting enough B12. For example, if a fortified plant milk
contains 1 microgram of B12 per serving then consuming three servings a
day will provide adequate vitamin B12. Others may find the use of B12
supplements more convenient and economical.
The less frequently you obtain B12 the more B12 you need to take, as B12 is best
absorbed in small amounts. The recommendations above take full account
of this. There is no harm in exceeding the recommended amounts or
combining more than one option.
Good information supports vegan health, pass it around.
If you don't read another word about B12 you already know all you need to know. If you want to know more, read on.
This information was prepared by Stephen Walsh, a UK Vegan Society
trustee, and other members of the International Vegetarian Union
science group (IVU-SCI), in October 2001. This information may be
freely reproduced but only in its entirety.
Vitamin B12 and vegan diets - Lessons from history
B12 is an exceptional vitamin. It is required in smaller amounts than
any other known vitamin. Ten micrograms of B12 spread over a day
appears to supply as much as the body can use. In the absence of any
apparent dietary supply, deficiency symptoms usually take five years or
more to develop in adults, though some people experience problems
within a year. A very small number of individuals with no obvious
reliable source appear to avoid clinical deficiency symptoms for twenty
years or more. B12 is the only vitamin that is not recognised as being
reliably supplied from a varied wholefood, plant-based diet with plenty
of fruit and vegetables, together with exposure to sun. Many
herbivorous mammals, including cattle and sheep, absorb B12 produced by
bacteria in their own digestive system. B12 is found to some extent in
soil and plants. These observations have led some vegans to suggest
that B12 was an issue requiring no special attention, or even an
elaborate hoax. Others have proposed specific foods, including
spirulina, nori, tempeh, and barley grass, as suitable non-animal
sources of B12. Such claims have not stood the test of time.
In over 60 years of vegan experimentation only B12 fortified foods and
B12 supplements have proven themselves as reliable sources of B12,
capable of supporting optimal health. It is very important that all
vegans ensure they have an adequate intake of B12, from fortified foods
or supplements. This will benefit our health and help to attract others
to veganism through our example.
Getting an adequate amount of B12
National recommendations for B12 intakes vary significantly from
country to country. The US recommended intake is 2.4 micrograms a day for
ordinary adults rising to 2.8 micrograms for nursing mothers. The German
recommendation is 3 micrograms a day. Recommended intakes are usually based
on 50% absorption, as this is typical for small amounts from foods. To
meet the US and German recommendations you need to obtain sufficient
B12 to absorb 1.5 micrograms per day on average. This amount should be
sufficient to avoid even the initial signs of inadequate B12 intake,
such as slightly elevated homocysteine and MMA levels, in most people.
Even slightly elevated homocysteine is associated with increased risk
of many health problems including heart disease in adults, preeclampsia
during pregnancy and neural tube defects in babies.
Achieving an adequate B12 intake is easy and there are several methods to suit
individual preferences. Absorption of B12 varies from about 50%, if
about 1 microgram or less is consumed, to about 0.5% for doses of 1000 micrograms
(1 milligram) or above. So the less frequently you consume B12, the higher the
total amount needs to be to give the desired absorbed amount.
Frequent use of foods fortified with B12 so that about one microgram of
B12 is consumed three times a day with a few hours in between will
provide an adequate amount. Availability of fortified foods varies from
country to country and amounts of B12 vary from brand to brand, so
ensuring an adequate B12 supply from fortified foods requires some
label reading and thought to work out an adequate pattern to suit
individual tastes and local products.
Taking a B12 supplement containing ten micrograms or more daily provides a similar absorbed amount to
consuming one microgram on three occasions through the day. This may be the
most economical method as a single high potency tablet can be consumed
bit by bit. 2000 micrograms of B12 consumed once a week would also provide an
adequate intake. Any B12 supplement tablet should be chewed or
allowed to dissolve in the mouth to enhance absorption. Tablets should
be kept in an opaque container. As with any supplement it is prudent
not to take more than is required for maximum benefit, so intakes above
5000 micrograms per week should be avoided despite lack of evidence for
toxicity from higher amounts.
All three options above should
meet the needs of the vast majority of people with normal B12
metabolism. Individuals with impaired B12 absorption may find that the
third method, 2000 micrograms once a week, works best as it does not rely on
normal intrinsic factor in the gut. There are other, very rare,
metabolic defects that require completely different approaches to
meeting B12 requirements. If you have any reason to suspect a serious
health problem seek medical advice promptly.
Symptoms of B12 deficiency
Clinical deficiency can cause anaemia or nervous system damage. Most
vegans consume enough B12 to avoid clinical deficiency. Two subgroups
of vegans are at particular risk of B12 deficiency: long-term vegans
who avoid common fortified foods (such as raw food vegans or
macrobiotic vegans) and breastfed infants of vegan mothers whose own
intake of B12 is low.
In adults typical deficiency symptoms
include loss of energy, tingling, numbness, reduced sensitivity to pain
or pressure, blurred vision, abnormal gait, sore tongue, poor memory,
confusion, hallucinations and personality changes. Often these symptoms
develop gradually over several months to a year before being recognised
as being due to B12 deficiency and they are usually reversible on
administration of B12. There is however no entirely consistent and
reliable set of symptoms and there are cases of permanent damage in
adults from B12 deficiency. If you suspect a problem then get a skilled
diagnosis from a medical practitioner as each of these symptoms can
also be caused by problems other than B12 deficiency.
Infants typically show more rapid onset of symptoms than adults. B12 deficiency
may lead to loss of energy and appetite and failure to thrive. If not
promptly corrected this can progress to coma or death. Again there is
no entirely consistent pattern of symptoms. Infants are more vulnerable
to permanent damage than adults. Some make a full recovery, but others
show retarded development.
The risk to these groups alone is reason enough to call on all vegans to give a consistent message as to
the importance of B12 and to set a positive example. Every case of B12
deficiency in a vegan infant or an ill informed adult is a tragedy and
brings veganism into disrepute.
The homocysteine connection
This is not however the end of the story. Most vegans show adequate B12
levels to make clinical deficiency unlikely but nonetheless show
restricted activity of B12 related enzymes, leading to elevated
homocysteine levels. Strong evidence has been gathered over the past
decade that even slightly elevated homocysteine levels increase risk of
heart disease and stroke and pregnancy complications. Homocysteine
levels are also affected by other nutrients, most notably folate.
General recommendations for increased intakes of folate are aimed at
reducing levels of homocysteine and avoiding these risks. Vegan intakes
of folate are generally good, particularly if plenty of green
vegetables are eaten. However, repeated observations of elevated
homocysteine in vegans, and to a lesser extent in other vegetarians,
show conclusively that B12 intake needs to be adequate as well to avoid
Testing B12 status
A blood B12 level measurement is a very unreliable test for vegans, particularly
for vegans using any form of algae. Algae and some other plant foods
contain B12-analogues (false B12) that can imitate true B12 in blood
tests while actually interfering with B12 metabolism. Blood counts are
also unreliable as high folate intakes suppress the anaemia symptoms of
B12 deficiency that can be detected by blood counts. Blood homocysteine
testing is more reliable, with levels less than 10 micromol/litre being
desirable. The most specific test for B12 status is methylmalonic
acid (MMA) testing. If this is in the normal range in blood (<370 nmol/L) or urine (less than 4 mcg /mg creatinine) then your body has
enough B12. Many doctors still rely on blood B12 levels and blood
counts. These are not adequate, especially in vegans.
Is there a vegan alternative to B12-fortified foods and supplements?
If for any reason you choose not to use fortified foods or supplements
you should recognise that you are carrying out a dangerous experiment -
one that many have tried before with consistently low levels of
success. If you are an adult who is neither breast-feeding an infant,
pregnant nor seeking to become pregnant, and wish to test a potential
B12 source that has not already been shown to be inadequate, then this
can be a reasonable course of action with appropriate precautions. For
your own protection, you should arrange to have your B12 status checked
annually. If homocysteine or MMA is even modestly elevated then you are
endangering your health if you persist.
If you are breast feeding an infant, pregnant or seeking to become pregnant or are an
adult contemplating carrying out such an experiment on a child, then
don't take the risk. It is simply unjustifiable.
Claimed sources of B12 that have been shown through direct studies of vegans to
be inadequate include human gut bacteria, spirulina, dried nori, barley
grass and most other seaweeds. Several studies of raw food vegans have
shown that raw food offers no special protection.
Reports that B12 has been measured in a food are not enough to qualify that food as
a reliable B12 source. It is difficult to distinguish true B12 from
analogues that can disrupt B12 metabolism. Even if true B12 is present
in a food, it may be rendered ineffective if analogues are present in
comparable amounts to the true B12. There is only one reliable test for
a B12 source - does it consistently prevent and correct deficiency?
Anyone proposing a particular food as a B12 source should be challenged
to present such evidence.
A natural, healthy and compassionate diet
To be truly healthful, a diet must be best not just for individuals in
isolation but must allow all six billion people to thrive and achieve a
sustainable coexistence with the many other species that form the
"living earth". From this standpoint the natural adaptation for most
(possibly all) humans in the modern world is a vegan diet. There is
nothing natural about the abomination of modern factory farming and its
attempt to reduce living, feeling beings to machines. In choosing to
use fortified foods or B12 supplements, vegans are taking their B12
from the same source as every other animal on the planet -
micro-organisms - without causing suffering to any sentient being or
causing environmental damage.
Vegans using adequate amounts of
fortified foods or B12 supplements are much less likely to suffer from
B12 deficiency than the typical meat eater. The Institute of Medicine,
in setting the US recommended intakes for B12 makes this very clear.
"Because 10 to 30 percent 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." Vegans should take
this advice about 50 years younger, to the benefit of both themselves
and the animals. B12 need never be a problem for well-informed vegans.
Good information supports vegan health, pass it around.
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1st edition October 31st 2001