Vitamin B-12, also called cobalamin, is a water soluble vitamin with a key role in the normal functioning of the brain and nervous system, and for the formation of blood. It is one of the eight B vitamins. If B12 deficiency occurs, DNA production is disrupted and abnormal cells called megaloblasts occur.
This results in pernicious anemia, an autoimmune disorder where B12 is not being absorbed or from a deficieny of B12 in the diet.. Symptoms include excessive tiredness, breathlessness, listlessness, pallor, and poor resistance to infection. Other symptoms can include a smooth, sore tongue and menstrual disorders. Anaemia may also be due to folic acid deficiency, folic acid also being necessary for DNA synthesis.
B12 is also important in maintaining the nervous system. Nerves are surrounded by an insulating fatty sheath comprised of a complex protein called myelin. B12 plays a vital role in the metabolism of fatty acids essential for the maintainence of myelin. Prolonged B12 deficiency can lead to nerve degeneration and irreversible neurological damage.
Vitamin B12 reduces homocysteine levels.
Both homocysteine, an amino acid associated with vitamin B12, and holotranscobalamin (holoTC), the biologically active fraction of vitamin B12, may have a role in the development of Alzheimer's disease (AD), the findings of a new Finnish study suggest.
Homocysteine is an amino acid that is produced by the body, usually as a byproduct of consuming meat. Amino acids combine together to form proteins. Elevated levels of homocysteine (>10 micromoles/liter)
In 1969, Dr. Kilmer S. McCully reported that children born with a genetic disorder called homocystinuria, which causes the homocysteine levels to be very high, sometimes died at a very young age with advanced atherosclerosis in their arteries. However, it was not until the 1990's that the importance of homocysteine in heart disease and stroke was appreciated.
In the recent Finnish study, among a group of elderly subjects followed up for 7 years, elevated homocysteine concentrations were associated with an increased risk of developing AD, whereas higher baseline holoTC values were independently related to a reduced risk for incident AD. No association was observed with folate or folic acid, another B vitamin.
"Our results indicate that vitamin B12 and related metabolites may have a role in Alzheimer's disease, but more research is needed before we can get conclusion on the role of vitamin B12 supplements on neurodegenerative diseases such as Alzheimer's disease," first study author Babak Hooshmand, MD, MSc, of the Aging Research Center, Karolinska Institutet, Stockholm, Sweden noted. Their results are published October 19, 2010 in the journal Neurology.
Cardiovascular Risk Factors, Aging and Dementia
An Important First Step
This study is "an important initial step relating plasma holoTC to risk of incident dementia and AD," Sudha Seshadri, MD, of Boston University School of Medicine in Massachusetts, writes in a commentary published with the study.
By way of background, Dr. Seshadri notes that, in the 1990s, several studies linked elevated homocysteine levels with an increased risk for stroke, cognitive decline, and dementia, including AD. Homocysteine can directly promote cerebrovascular disease and neuronal injury through a variety of mechanisms.
Measuring Homocysteine and B12
Homocysteine and B12 can be measured through simple blood tests.
Dietary Sources of B12
The only reliable unfortified sources of vitamin B12 are meat, dairy products and eggs. There has been considerable research into possible plant food sources of B12. Fermented soya products, seaweeds and algae have all been proposed as possible sources of B12. However, analysis of fermented soya products, including tempeh, miso, shoyu and tamari, found no significant B12.
Spirulina, an algae available as a dietary supplement in tablet form, and nori, a seaweed, have both appeared to contain significant amounts of B12 after analysis. However, it is thought that this is due to the presence of compounds structurally similar to B12, known as B12 analogues. These cannot be utilised to satisfy dietary needs. Assay methods used to detect B12 are unable to differentiate between B12 and it's analogues, Analysis of possible B12 sources may give false positive results due to the presence of these analogues.
Researchers have suggested that supposed B12 supplements such as spirulina may in fact increase the risk of B12 deficiency disease, as the B12 analogues can compete with B12 and inhibit metabolism.
Good sources of vitamin B12 for vegetarians are dairy products or free-range eggs. Ω pint of milk (full fat or semi skimmed) contains 1.2 µg. A slice of vegetarian cheddar cheese (40g) contains 0.5 µg. A boiled egg contains 0.7 µg. Fermentation in the manufacture of yoghurt destroys much of the B12 present. Boiling milk can also destroy much of the B12.
Vegans are recommended to ensure their diet includes foods fortified with vitamin B12. A range of B12 fortified foods are available. These include yeast extracts, Vecon vegetable stock, veggieburger mixes, textured vegetable protein, soya milks, vegetable and sunflower margarines, and breakfast cereals.
The current nutritional consensus is that no plant foods can be relied on as a safe source of vitamin B12.
Related Lab Tests found at www.saveonlabs.com
Homocysteine, Plasma is important in understanding your risk for cardiovascular disease.
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