Vitamin B12 is an essential vitamin needed in DNA synthesis. It?s critical in maturing red blood cells in your bone marrow. And it helps nerve fibers form and function in your brain, spinal cord and peripheral nerves.
With a deficiency of B-12, vital cells will not develop properly. You can become anemic and suffer from spinal cord damage.
B-12 is also required to turn the amino acid homocysteine into methionine. If you have a B-12 deficiency, homocysteine will build up to toxic levels in your bloodstream, damaging your arteries and leading to atherosclerosis.
Not to be grim, but advanced B-12 deficiency will lead to paralysis, dementia and death.
Where Does B-12 Come From?
Vitamin B-12 comes from microorganisms? mostly bacteria that live in soil, water, and the digestive tracts of animals.
In centuries past, people could get B-12 by drinking from streams. Or by working in gardens and then eating without washing their hands thoroughly. Since we no longer do these things, ?natural? plant based sources of Vitamin B-12 have dropped out of modern life.
It?s true that there are bacteria in the human gut that synthesize B-12. But they live well beyond the part of the intestine where B-12 is absorbed.
If you?re a vegetarian, please read Lesson 9.2: Addendum for Ovo-Lacto Vegetarians after this lesson. However, if you?re a vegan, there are only two reliable sources of B-12: fortified foods and supplements. These are covered in further details later in this lesson.
Storage In Your Body
For B-12 to be absorbed from your gut into your bloodstream, it must combine with a protein secreted by the stomach lining called intrinsic factor.
B-12 is stored in your blood, liver and muscles. 0.2% of your B-12 stores are lost each day. So if you don?t consume a regular, reliable source of B-12, you?ll eventually become deficient. This could take years to manifest fully.
Unfortunately, the medical literature brims with case studies of vegans ? infants, children, adults, and the elderly ? who?ve incurred bodily damage from B-12 deficiency.
Long-term vegans who don?t supplement may not appear to suffer in the short term. But they may actually have elevated levels of homocysteine, or subtle neurologic dysfunction.
Two subgroups of vegans are at particular risk.
- Vegans who avoid fortified foods like cereal, rice milk, and soy milk. These most typically include raw food vegans and macrobiotics.
- Infants who are breast fed, and whose vegan mothers don?t consume enough B-12.
If these groups don?t supplement their diets with a reliable B-12 source, they will eventually develop deficiency.
Signs of Deficiency
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.
These symptoms often develop gradually over several months to a year before the B-12 deficiency is recognized.
They?re usually reversible on administration of B-12. But there?s no entirely consistent and reliable set of symptoms. And there are cases of permanent damage in adults from B-12 deficiency.
If you suspect a problem, then get a skilled diagnosis from a medical practitioner. Unfortunately, the symptoms above can be caused by other problems too, not just B-12 deficiency.
How Can You Test For B-12 Deficiency?
Measuring B-12 levels in the blood is not accurate. That?s because the B-12 analogues in sea vegetables, green powders, and other foods can give a falsely high reading of B-12 in your blood.
What?s more, even if you have ?normal? B-12 levels, damage to your nerves and an elevation of homocysteine levels can still occur.
Damage to your nerves and brain can occur long before anemia manifests. So waiting to see if anemia shows up is waiting too long.
For these reasons, the best tests measure the amount of homocysteine and MMA (methylmalonic acid) in your blood. These substances increase when B-12 is deficient. If either of these levels (or both) are elevated, you have presumptive evidence of a B-12 deficiency. It should be treated immediately with oral B-12 supplementation.
If you do get your B-12 level checked, the value should be at least 350 mcg/dl.
How Much B-12 Do You Need To Take Daily To Avoid Problems?
Little of the B-12 you swallow is actually absorbed. So we recommend a daily intake of?
- 5 mcg daily from fortified food like cereal, rice milk, and soy milk. Read the food label to determine how much B-12 is present in each serving.
- 100 mcg from a daily supplement, preferably chewed to increase absorption. We recommend http://www.veganmultivitamin.com, which contains 30 mcg of Vitamin B12? that?s 500% the US RDA.
- 2000 mcg from a weekly supplement to keep your B-12 level in the safe range.
Vitamin B-12 can be absorbed orally, even if intrinsic factor is deficient, if enough B-12 is taken.
Where B-12 is Not Found.
The soil particles on unwashed vegetables or vegetables do not supply adequate B-12 to prevent deficiency. This is true even if they?re left sitting at room temperature.
Foods commonly reported as ?good B-12 sources? are usually tested with methods that measure B-12 analogues. Those methods give no accurate measure of the true B-12 content, nor whether it might actually be dangerous from its analogue content.
These foods include tempeh, tofu, amesake rice, barley miso, miso, natto, rice miso, shoyu, tamari, and umeboshi prunes. These foods don?t contain B-12 on a consistent enough basis to fulfill your daily requirements. 
Seaweeds, especially nori, have so many B-12 analogues, that they may actually cause B-12 deficiency by blocking the action of active B-12.
Only dulse may be a reliable B-12 source. But to meet your B-12 requirements from dulse alone, you?d have to eat large amounts of it daily. And the amount of iodine from that much dulse would likely become toxic to your thyroid gland.
Merchandisers of blue-green algae (from Klamath Lake, OR), chlorella and spirulina all claim B-12 is present in their products. However, the tests they use all measure analogues. So the amount of active B-12 in their products is unknown and the presence of analogues in these products might actually precipitate B-12 deficiency.
If a merchandiser states that their product is a good source of B-12, they should offer ?gold standard? proof. Namely, they should show that their product lowers levels of homocysteine or MMA in the blood. All other test methods are suspect.
Where B-12 is Found in Vegan Diets.
Vitamin B-12 is commonly added to commercial rice milk, soy milk, and cereal. It is also added to many meat analogues made from wheat gluten or soybeans. However, meat analogues tend to be high in salt, fat, and artificial ingredients; so we do not recommend them.
Read the labels to see how much B-12 is in each serving.
Brewer?s and nutritional yeast do not naturally contain B-12. But one brand, Red Star Vegetarian Support Formula, also known as Red Star Yeast T6635+, fortifies their product with 5 mcg per tablespoon.
In Lesson 9.4, we provide suggestions for including nutritional yeast in your everyday meals. However, we have two cautions against relying upon Red Star nutritional yeast as your sole B-12 source:
- It?s often sold from bins in natural food stores, run by humans. Humans not infrequently make mistakes and the wrong yeast can be ordered from a list of many yeast products, or a non-fortified type be placed in the bin labeled as a fortified product.
- B-12 deteriorates in sunlight, so even the advertised amounts may not be present in the product one buys.
If you buy B-12 fortified nutritional yeast, be sure to keep it in your refrigerator or freezer, and keep it out of the sunlight.
Note: Yeast products, like nutritional yeast, will not cause the growth of candida or any other type of yeast in your body. Besides being a totally different kind of yeast from candida, nutritional yeasts are processed so that no living yeast organisms are present.
Is There A Vegan Alternative To B-12 Fortified Foods and Supplements?
The short answer is ?No.?
As mentioned earlier, our ancestors could get B12 by drinking from streams. Or by working in gardens and then eating without washing their hands thoroughly. Since we no longer do these things, ?natural? plant-based sources of Vitamin B-12 have dropped out of modern life.
And the modern world, with its oxidizing air pollution, chlorinated drinking water, thinning ozone layer, etc, places metabolic demands on our bodies that the ancients and their diets never faced.
If you?re vegan, eating B-12 fortified foods or supplements is not optional. It?s absolutely necessary.
If you?re a purist who doesn?t eat commercial rice milk, soy milk, or cereal ? and you also shun supplements ? then have your B-12, MMA, and homocysteine levels checked annually. If the values become abnormal, begin B-12 supplementation immediately.
However, don?t even consider this option if you?re pregnant, trying to become pregnant, or nursing an infant.
Recommendations: Food Sources and Supplements.
Both vegans and vegetarians should obtain sufficient B-12 from fortified food or supplements. Again, we recommend http://www.veganmultivitamin.com, which contains 30 mcg of Vitamin B12? that?s 500% the US RDA.
It is not wise to rely upon any sea vegetables such as algae, nori, or spirulina or upon brewer?s yeast, tempeh, or ?living? vitamin supplements that use plants as a sole source of B12.
Nor is it wise to rely solely on one type of fortified food, such as Red Star Nutritional Yeast.
Recommendation for Vegan Infants.
The Institute of Medicine recommends that infants of vegan mothers be supplemented with B12 from birth. That?s because their stores at birth and their mother?s milk supply may be low.
Exceptions to these Recommendations.
People with digestive or malabsorption diseases ? such as pernicious anemia ? B12 metabolism defects, kidney failure, or cyanide metabolism defects should consult an accredited health professional.
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 Dong & Scott29 (1982, USA) examined 83 subjects from an American Natural Hygiene Society conference. They tended to follow natural hygiene diets consisting of whole raw fruits, vegetables, nuts, and seeds, with a minimal intake of grains and legumes. They considered this to be a natural primate diet and believed their bodies received B12 through small intestinal bacteria which live only in the intestines of those who follow whole raw food diets. Table 8.5.1 shows the results among subjects who did not supplement with B12. Macrocytosis among the vegetarians was minimal. One 63-year-old vegan with a sB12 of 117 (MCV = 86 fl) had a nerve related disorder. For males who did not take B12 supplements, there was a correlation between length of time as a vegetarian and lower sB12. Among subjects who had taken B12 or multivitamins, all had sB12 levels above 200 pg/ml. Dong & Scott concluded that there is no indication that natural hygiene vegetarian diets contribute to higher sB12 levels than other vegetarian diets.
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? Food and Nutrition Board, Institute of Medicine. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington, DC: National Academy Press; 2000.
 What Every Vegan Should Know about Vitamin B12, http://www.veganoutreach.org/health/b12letter.html