Vitamin b12

One of the most important nutrients we get from animal foods is vitamin B12. Vitamin B12 works with folic acid in many body processes including synthesis of DNA, red blood cells and the insulation sheath (the myelin sheath) that surrounds nerve cells and facilitates the conduction of signals in the nervous system.
ABSORPTION
Absorption of vitamin B12 is a complex process, subject to problems at several points.
B12 from animal food enters the stomach as part of animal proteins and must first be liberated by pepsin and hydrochloric acid. Free B12 then attaches to R-protein, which is released from the salivary cells and parietal cells (the same cells that release hydrochloric acid). B12 then binds with the intrinsic factor and proceeds through the gut to the lower portion of the small intestine, where the intrinsic factor-B12 complex attaches to cell receptors, a process that involves calcium.
Thus, deficiencies in pepsin, hydrochloric acid, R-protein, pancreatic enzymes, intrinsic factor, calcium and cell receptors can all lead to B12 deficiency through blocked absorption.
Deficiency in the required enzymes can block this conversion.
Fortunately, the body absorbs about 1-5 percent of free B12 by a process of passive diffusion. Thus supplementation with large doses of crystalline B12 or with foods extremely rich in B12 can successfully treat deficiencies caused by compromised protein digestion or lack of R-protein, intrinsic factor or pancreatic enzymes. Supplementation with the coenzyme forms methylcobalamin and adenosylcobalamin (the forms found in the cells) can overcome B12 deficiency in the cells caused by lack of, or malfunction of, conversion enzymes.
VEGETARIANS
B12 is found almost exclusively in animal foods such as liver, kidney, meat, fish, shellfish, milk products and eggs but the original source of B12 in nature is bacteria, the only creatures able to manufacture this vitamin. Some studies indicate that B12 is better absorbed from milk than from meat.5 However, one source indicates that B12 in milk is destroyed by boiling.6 Analysis of B12 in pasteurized milk reveals only a 10 percent loss; however pasteurization deforms the milk proteins that aid in B12 absorption.7
Interestingly, some sources claim that fermentation of yoghurt from milk lowers B12 levels,8 although food tables indicate similar levels in commercial milk and yoghurt.
Proponents of vegetarianism pointed to inhabitants of India, who did not seem to exhibit signs of B12 deficiency in spite of very low levels of animal foods in the diet. Yet as early as 1974, an American study found that 92 percent of vegans, 64 percent of lactovegetarians, 47 percent of lacto-ovovegetarians and 20 percent of semi-vegetarians have blood levels below normal, that is, below the low range that marks the onset of pernicious anemia.10
Plant foods said to be sources of B12 actually contain B12 analogs (called cobamides)--substances that block the uptake of true B12 and increase the body’s need for the nutrient.12 A surprising source of cobamides is bacterial overgrowth in the small intestines, which can produce B12 analogs.13 The use of antibiotics, or a diet high in refined carbohydrates, can encourage the proliferation of bacterial overgrowth and lead to B12 deficiencies.
The late Victor Herbert, a noted B12 researcher, maintains that many multivitamin products contain spurious and even dangerous analogs of B12 possibly formed when crystalline B12 interacts with other nutrients in multivitamin products, such as vitamin C, iron and copper.14
High levels of folic acid can accelerate neuropsychiatric complications in persons with B12 deficiency.15 Since folic acid intakes of vegetarians tend to be high (from green vegetables and from grain products that have been fortified with folic acid), those following a vegetarian lifestyle may be at increased risk of neurological and psychological problems.
The body stores considerable B12 in the liver. Thus a delay of 5-10 years may separate the beginning of a vegetarian diet (or absorption problems) and the onset of deficiency symptoms. Some people have a more efficient recycling system than others and hence can go longer on a vegetarian diet without signs of deficiency. However, more B12 is excreted in the presence of high levels of fiber, a common feature of vegetarian diets.17
Vegan and vegetarian diets present a real danger for growing children because their stores are very low, especially if their mothers avoided animal foods during pregnancy and lactation. The scientific literature contains numerous case studies describing severe anemia, dramatic growth retardation, irritability and delays in the acquisition of motor skills in B12-deficient children from vegetarian families.
In a recent study, researchers assayed cognitive development in 72 young people raised on diets free of all animal products until at least the age of six and then on a diet containing milk and eggs. When compared with children who had eaten normal mixed diets (including meat) all their lives, they scored substantially lower on tests measuring spatial ability, short-term memory and "fluid intelligence," that is, the capacity to solve complex problems, abstract thinking ability and the ability to learn.18
MEASURING B12 DEFICIENCY
American medical opinion defines blood levels lower than 200 pg/mL as an indication of deficiency. This number is based on the level associated with the most severe manifestation of deficiency, pernicious anemia. Physicians in these countries consider blood levels of 500-1300 to be the normal range.19
According to Dr. John Dommisse, an expert in B12 deficiency, the acceptance of high levels as normal in Japan, and the willingness to readily treat psychiatric symptoms with B12 explains the low rates of Alzheimer’s dementia in that country--as well as the reason for the very high rates of Alzheimer’s in the US.20
PERNICIOUS ANEMIA
The most common underlying cause of pernicious anemia is an autoimmune reaction that attacks and destroys the stomach cells that produce intrinsic factor. The disease is characterized by immature, abnormally large red blood cells (macrocytes), which are very inefficient at carrying oxygen, and by white blood cells with abnormal nuclei.
Early symptoms of pernicious anemia include paleness, weakness and fatigue; severe anemia causes shortness of breath, dizziness and a rapid heart rate.
Those suffering from pernicious anemia require very high levels of B12 to overcome the lack of intrinsic factor. Today doctors prescribe injections or oral supplements of even higher doses.
SYMPTOMS OF AGING
B12 deficiency mimics many of the features of old age--ataxia (shaky movements and unsteady gait) muscle weakness, spasticity, incontinence, slowed reactions, memory loss, disorientation, depression and confusion can all occur when B12 levels are low.
Whether or not Alzheimer’s disease constitutes a condition of B12 deficiency is the subject of considerable debate among physicians. A recent and fascinating study of a family in Wales provides convincing evidence that low levels of B12 and Alzheimer’s are linked.22
Researchers evaluated members of a family with a genetic predisposition towards Alzheimer’s disease. They found that four out of six (67 percent) family members with confirmed Alzheimer’s disease had abnormally low blood levels of vitamin B12, compared to one out of 12 (8 percent) who were at equal genetic risk for developing Alzheimer’s but did not. The researchers speculated that a vitamin B12 deficiency could result in impaired methylation reactions in the central nervous system, a characteristic feature of Alzheimer’s, as well as the possibility that the genetic predisposition to Alzheimer’s may actually be related to a genetic impairment in the ability to absorb B12.
Investigators have found vitamin B12 deficiency in 3-42 percent of persons aged 65 and older. In a recent study of geriatric patients, 43 percent had levels below 295 pmol/L.23 Should a higher point be used as bench mark, it is likely that almost all seniors would be diagnosed as deficient.
Research shows tremendous potential for B12 to reverse mental decline in elderly patients.
HEART DISEASE
It was Dr. Kilmer McCully who elucidated high blood homocysteine levels as a marker for heart disease.
CANCER
Low levels of B12 are associated with cancer of the cervix27 and the breast28 in human studies.
In one study, high levels of vitamin B12 were associated with an up to 3-fold increase in risk of developing prostate cancer.29
Furthermore, holistic physicians have reported good results giving B12 to cancer patients. Dr. Max Gerson, who treated terminal cancer patients with extraordinary success, gave his patients liver injections, often combined with additional B12.32
NERVOUS DISORDERS
Recurrent seizures may be a manifestation of B12 deficiency. One study found that individuals who suffered from seizures had low B12 levels.36
Other neurological problems associated with B12 deficiency include urinary incontinence37 and migraine headaches.38 In one case history, B12 worked better than steroids as a treatment for Bell’s palsy.39 Another case study reports that shaky leg syndrome responds well to B12 injections.40
FERTILITY
B12 plays a critical role in cellular replication so it is no surprise that deficiency can manifest as low sperm count. High doses are key to successful treatment. In one study, 27 percent of men with sperm counts less than 20 million given 1000 mcg per day of vitamin B12 were able to achieve a total count in excess of 100 million;41 in a study in which men were given 6000 mcg per day, 57 percent of men with low sperm counts demonstrated improvement.42
As pernicious anemia often leads to infertility, B12 supplements can allow a woman to conceive. Prolonged B12 deficiency results in infertility.
OTHER DISEASES
Osteoblast activity in the bones depends on B12 and bone metabolism is affected by deficiency.44 Low B12 is associated with osteoporosis45 and B12 supplements can help remineralize the bones.46
B12 deficiency occurs in 10-35 percent of all patients tested positive for HIV, attributed to various factors such as low intake, reduced absorption and depletion by drugs like AZT. B12 deficiency exacerbates neurological symptoms of AIDS. Researchers in Germany have reported using B12 as part of the successful treatment of a variety of skin conditions, such as hives, seborrhea, dermatitis, eczema, shingles and lupus.49 One journal article describes a successful treatment for psoriasis.50 Huge doses were needed--30 injections of 1000 micrograms each. Deafness is associated with B12 deficiency; supplements have been useful in treating tinnitus and noise-related hearing loss.55
B12 may be necessary for antibody response;58 low levels are associated with impaired immunity and increased infections.59
B12 injections have been beneficial in treating viral hepatitis.62
The many factors in our modern lifestlye that block the complicated uptake pathways of this important nutrient--from nutrient deficiencies to exposure to toxins to factors in processed foods that cause reduced stomach acid, autoimmune disease and enzyme disruption--make it difficult to obtain sufficient quantities from our normal diet; and since vitamin B12 in supplements is produced in exactly the same way as B12 in nature, that is, by bacterial fermentation, the danger of high doses in most cases is negligible.