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
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
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.