Vitamin B12 (cyanocobalamin) is an oxygen carrier; it decreases blood cholesterol; it metabolizes fat. Vitamin B12 is essential in humans for healthy nerve tissues. Its deficiency is associated with heart palpitations.
The term "Vitamin B12
" refers to a group of cobalamin
compounds, of which the most frequently used is cyanocobalamin. All vitamin B12
found in nature is made by microorganisms (bacteria
essentially), and none is found in sterile plants. In the early to mid 1800s, an unrecognized vitamin B12 deficiency was referred to as pernicious anemia
because it was almost always fatal. It was not until 1948, though, that researchers finally isolated the active principle in liver
now called vitamin B12. The isolation used a charcoal filter that added the stabilizing effects of cyanide, thus cyanocobalamin is one of the major stable forms used today for supplementation purposes.
SourceFood Sources of Vitamin B12.
Those who don't like taking supplements can eat fortified foods, including fortified soy milks and rice milks, breakfast cereals, fake meats, sea weeds, one type of nutritional yeast
(Red Star Brand Vegetarian
Support Formula) and so on. Read labels. The main thing to remember if you rely exclusively on fortified foods is that you have to eat them at least twice each day. Some people prefer this method because it is the most natural. For example, one might have some B12-fortified cereal or soy milk for breakfast, and for supper also a serving of something with B12
in it, like another cup of fortified soymilk or a teaspoon of B12-fortified nutritional yeast
The best sources of B12 are animal-derived: liver
, meat, salt-water fish, oysters, milk, eggs, aged cheese such as Roquefort, and fortified brewer's yeast. Vitamin B12
occurs naturally in the soil and on the surface of unwashed fruits and vegetables. Those on an animal-free diet may wish to eat unwashed, organic produce whenever possible.
There is debate over the reliability of non-animal sources of Vitamin B12. It was found that people on vegan
diets had lower levels of serum B12 levels than the general population. In particular, infants breast-fed or fed a macrobiotic
diet directly are at a great risk of developing B12 deficiency.
Non-animal sources which claim to have significant amounts of B12 such as tempeh, micro-algaes (spirulina, chlorella
), miso, tamari, and sea vegetables (nori, arame, kombu, wakame) have been found to have negligible amounts, or B12 analogues that show up on lab tests, but don't have the activity of real B12.
It should be noted that there are different techniques for measuring the B12 content of foods. Furthermore, the B12 content in fermented foods, such as tempeh, may be different due to varying production techniques. In Indonesia, traditionally-produced tempeh is loaded with B12-producing bacteria
which grow on the molds commonly growing on the food. In the U.S., however, large scale production and improved sanitation decreases the mold
and bacteria and the subsequent B12 content of the food. The most reliable non-animal, but natural, source of B12 seems to be fortified brewers yeast
Function; Why it is Recommended
Like most of the vitamins, B12
is required as a cofactor
for various enzymes. Every DNA-synthesizing cell requires vitamin B12
. It facilitates the cyclic metabolism of folic acid
, which is essential for thymidine (one of the four DNA bases) synthesis. It also transfers a methyl group from methylfolate, helping to convert homocysteine to methionine
Because plants have no appreciable amounts of B12
are often at risk of slowly developing vitamin B12
There appears to be some confusion among practitioners of natural medicine about whether oral, sublingual or intramuscular administration is preferable for patients requiring vitamin B12
Blood levels of B12
indicate that sublingual B12 becomes available as early as 15 minutes after administration and are still elevated at 24 hours, suggesting that a once-daily dose of 2,000-4,000mcg would be an effective preventive measure. [Bhat N.K. – Presentation at the 43rd Annual Meeting, American Academy of Allergy and Immunology, 1987
A year's supply of 1,000mcg vitamin B12 tablets costs under $20, which is less than the cost of going to the doctor's office for injections. On the other hand, patients who are likely to be noncompliant with oral therapy should be seen regularly by a doctor and treated with intramuscular injections.
The current US RDA for vitamin B12 is 6mcg, but less for children and more for nursing and pregnant women. For those suspected of having low B12 levels, 2,000mcg once a day for two weeks sublingually should replenish stores. Those with problems absorbing B12 should continue taking their B12 sublinbgually.
When vitamin B12 is being used for its pharmacological
effects, as in the treatment of fatigue
, Bell's palsy
, diabetic neuropathy
, subdeltoid bursitis
, or asthma
, intramuscular injections appear to be preferable to oral administration. Although there is little published research in this area, clinical observations suggest that orally administered vitamin B12 is not particularly effective against these conditions. It appears that very high serum concentrations are usually needed for vitamin B12 to exert its pharmacological
effects, and that these serum concentrations can be achieved only with IM administration.Long-term B12 Supplementation
B12 supplementation is especially important for those who consume few or no animal products – vegetarians
and raw-food vegans/fruitarians.
There are two basic ways to use supplements – weekly or daily. Probably the simplest method is to chew up one B12 supplement containing 2,000mcg or more once a week. The reason you should ideally chew or let it dissolve under your tongue is to enhance absorption. For some people it is hard to remember to take something once a week and they may prefer to get into the habit of taking something every day, which is more physiologically natural.
If you take your B12 supplement every day then you can take much less – you only need about a 100mcg a day that way. This can be achieved through chewing up the smallest tablet you can find every day, or even just a piece of one tablet.