12 Points on
© Dr. Peter Hinde
Ph.D., D.N.Th., D.Iridol.
updated: April 2006
1Vitamin B12 is an essential nutrient. The chemical names for the form of B12 found most commonly in foods is hydroxocobalamin. In the body conversion occurs to the active forms adenosylcobalamin, and methylcobalamin. The usual synthetic form of the vitamin is cyanocobalamin which occurs only in small amounts naturally. The Recommended Daily Allowance (USA) is 2.4 micrograms per day. This increases by 0.2 micrograms during pregnancy and 0.4 micrograms during lactation.
An article in the American Journal of Clinical Nutrition states that mild deficiency symptoms can occur in intakes of less than 6 micrograms per day. In foods vitamin B12 is at its highest in liver at around 100 and kidney at 55 micrograms per 100g. The oily fish contain 4-12; white fish 0-2; red meats 1-3 and white meats 0-2 micrograms per 100g. Eggs contain 2.5 and cheese 1-1.5 micrograms per 100g. Animal fats such as butter contain only trace levels.
2If taken orally as a constituent of foods, it is combined with first one factor called R-protein and later with intrinsic factor, both of which are produced in the stomach. This avoids its degradation by bacteria or its digestion so that it can it be absorbed in the small intestine. Passive (unbound) absorption accounts for only 1-3% of the total absorption.
3Vitamin B12 is a coenzyme , that is, it is required by at least 2 enzymes for their functionality. The first breaks down homocysteine to methionine. The other breaks down methylmalonyl-CoA to succinyl-CoA; if this does not occur then the methylmalonyl-CoA is converted to methylmalonic acid (MMA). Serum or urine levels of MMA are the most reliable test for B12 deficiency in the general tissues of the body.
4Vitamin B12 is an important nutrient in nervous tissue, helping to build myelin sheaths around nerves by carrying methyl groups to the nerve tissue. It is a potent brain detoxifier and the natural protective agent against the negative effects of the neurotransmitter glutamate which otherwise leaves nerves in a hyperactive state. The only form of the vitamin used in the nervous system is methylcobalamin.
The Blood Brain Barrier (BBB) is a highly selective membrane protecting the delicate nerve tissues of the brain from mineral ions and other substances which would disturb its function. B12 does not easily cross the BBB. It is thus possible to have normal B12 levels in the body in general but a deficiency in nervous tissue. A test of homocysteine levels in the cerebrospinal fluid is a reliable test for nervous system deficiency, whereas the MMA urine test is not.
5Around 5mg of vitamin B12 is stored in the liver and, in the absence of intake, stores can last between 5 months and 30 years (due to recycling of the vitamin) before deficiency symptoms become apparent.
Early deficiency symptoms include unusual fatigue, faulty digestion, no appetite, nausea, or loss of menstruation.
Later symptoms include any of the following:
Not all symptoms occur in all cases of deficiency. Additionally, since deficiency of B12 leads to elevated homocysteine levels, it contributes to its resulting varied pathology including arterial disease.
6Vitamin B12 is protein-bound in foods and requires good protein digestion to be utilised. People with heavy yeast infection in the intestines have an impairment of intrinsic factor production as well as faulty digestion, and many of the mental symptoms within chronic fatigue syndrome may be related to B12. Also the symptoms of the terminal stage of AIDS are identical to those of severe B12 deficiency.
B12 absorption also requires normal levels of absorption in the small intestine, with relevance in for example, Crohn's Disease. Additionally hydroxocobalamin (or the synthetic cyanocobalamin) undergoes conversion to active forms in the liver and this conversion mechanism can be inadequate where liver function is impaired or there are certain other nutrient deficiencies.
7Vitamin B12 is contained within a group of chemicals called corrinoids which occur in foods. The corrinoids close to B12 are termed B12 analogues and may be active or inactive in the body. Some inactive B12 analogues can be active in bone marrow but not in nervous tissue, thus making a diagnosis of deficiency by the presenting symptoms difficult. Current chemical analysis is not able to assess whether the analogue is active or inactive. This can only be verified by feeding the food to a human and testing the resulting MMA level. Inactive analogues interfere with active forms, quickening the onset of symptoms in marginal cases.
8As of 2004 no plant sources of vitamin B12 had been found, though many had been tested including various seaweeds, algae and fermented foods. Where claims have been made as to B12 being present in a plant source, it has not been based on the test for MMA levels, and any subsequent tests have found no reduction in MMA, proving the presence only of inactive analogues.
9Vitamin B12 is produced in the human intestine by some of the bacteria naturally present. A study in the 1950's verified that vegans with pernicious anaemia could be returned to normality by isolating the B12 analogues from their faeces and feeding them back orally, where it could be combined with intrinsic factor. This proved that the forms produced in the intestines contain active B12 analogues, but that insufficient is absorbed passively to prevent deficiency.
A group of Finnish people living solely on fermented vegetable foods believed that vitamin B12 was produced by the fermentation processes. When their MMA levels were checked over a certain period they were found to be increasing, proving that normal methods of fermenting foods does not result in B12 production, but only its inactive analogues. It is assumed that passive absorption from B12 produced by gut bacteria in herbivorous animals is adequate due to the increased length of, and increased fermentation time in, their intestines. Additionally many "herbivores" eat insects and faeces.
10Vitamin B12 can be destroyed by cooking for a long enough time. There is thus an advantage to eating some raw animal protein. Raw food vegans, however, have not been shown to have any advantage over other vegetarian groups.
11Several foods are fortified with a synthetic form of the vitamin, including most yeast extracts and many breakfast cereals. This is how many vegans are maintaining their levels of B12 . This method of obtaining B12 is highly risky since levels cannot be guaranteed in each of these foods. The only sure way for a vegan to maintain levels of the vitamin is to take a synthetic form as a supplement.
12Inorganic mercury is known to accumulate on the BBB. It is thought that it oxidises the cobalt atom in methylcobalamin, making it far less able to cross the barrier. Inorganic mercury is thus a creator of deficiency of B12 in the nervous system and symptoms usually attributed to mercury toxicity in the brain and nerves are due to its effect on B12.
Inorganic mercury exposure is most commonly from mercury amalgam dental fillings and vaccines. Psychiatrist John Dommisse in the USA claims to have reversed 100% of his pre-Alzhemiers patients with the use of methylcobalamin as well as many cases of depression. Methylcobalamin is highly recommended by the Swedish Association of Dental Mercury Patients.
It has been used successfully in the treatment of Chronic Fatigue Syndrome and Fibromyalgia - more than 60% of these patients have tested for low levels in the cerebrospinal fluid. It has been used successfully as part of treatments in Autism, Schizophrenia and Multiple Sclerosis and has great potential in Parkinson's Disease and Muscular Dystrophy as well as other neurological or psychological disorders.
In such cases intramuscular injections or sublingual liquids or lozenges of methylcobalamin are maximally effective in combating deficiency symptoms, since they by-pass the complex absorption process in the intestines. There is no evidence for toxicity of methylcobalamin. Up to 40mg per day has been used therapeutically in some cases. Large doses have been used since it must overwhelm the effect of any mercury on the BBB.
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