Vitamin B12, also known as cyanocobalamin or methylcobalamin, is an essential nutrient in the B-complex of the eight B water-soluble vitamins. This nutrient must be consumed through animal foods (although supplementation may be more ideal) to ensure adequate intake. Vitamin B12 is structurally the largest and most complex of all the vitamins that have been discovered, and a surge of research is coming to the forefront displaying its awesome power in human health.
Role of Vitamin B12
Vitamin B12 is integral to normal, healthy energy metabolism in all cells of the body, as well as amino acid and fatty acid metabolism. B12 is also extremely important in a myriad of other vital physiological processes such as brain function, nervous system health, production of the myelin sheath (nerve insulation), red blood cell formation, bone marrow health, and DNA synthesis/regulation.
A unique nutrient, vitamin B12 isn't produced by plants, animals, or even fungi. Instead, this essential vitamin is produced only by certain bacteria. Human requirements for vitamin B12, as set by the Daily Recommended Intake (DRI) are 2-3 micrograms/mcg (microgram is one millionth of one gram) per day, upwards of 4-7 micrograms/mcg per day in lieu of recent research.
Unfortunately, research demonstrates that intrinsic factor only allows upwards of 1.5 mcg of B12 absorption per feeding. Keep this in mind when planning your daily meals, and consider quality B12 supplementation on a daily basis to ensure adequate intake. There is no upper limit on Vitamin B12 and even extremely high doses of B12 have been shown to be safe with virtually no side effects.
What Constitutes Deficiency?
Vitamin B12 is used by the body from the food and/or supplements we intake daily. In a healthy adult, the body can store up to 3 to 5 years worth of vitamin B12 (a minuscule two to five milligrams in total), in large part because of the efficient use and recycling of B12 by the liver.
Over 50% of total body reserves are stored in the liver.  This is one of the main reasons why a B12 deficiency doesn't show up until years after poor intake. Common blood testing ranges for vitamin B12 is measured in ng/L (nanograms per liter of blood) and can be ordered by general physicians or online via specialty mail-order test companies. Vitamin B12 blood range values include:
- 180-914 ng/L – Normal high/low range
- 450+ ng/L – Healthy/Optimal
- 180-400 ng/L – Conditionally low levels
- 150-180 ng/L – Low levels where disease symptoms start (pernicious anemia)
- 150 or below – Deficiency levels
Blood testing for B12 is a very important step everyone should consider doing to be certain that their levels are sufficient for optimal health as well as healthy brain/nervous system function. Though more medical doctors are becoming aware of B12′s importance and are beginning to test their patients for this crucial vitamin, it's not something that is widely practiced–yet. Depending on test results and possible symptoms, other simple follow-up blood tests which indirectly test for B12 status may …read more