Vitamin B12, also known as cobalamin, 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|
|180-400 ng/L||Conditionally low levels|
|150-180 ng/L||Low levels where disease symptoms start|
Be aware that in older adults levels between 200 and 500 pg /mL may also produce symptoms of vitamin B12 deficiency.
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 be suggested, including homocysteine and methylmalonic acid/MMA.
Researchers have discovered that B12 deficiency generally occurs in four distinct stages:
Declining blood levels and cell stores.
Low cellular levels.
Functional B12 imbalance characterized by increased blood level of homocysteine/MMA and a decreased rate of DNA synthesis.
Clinical signs/symptoms of B12 deficiency like macrocytic anemia, peripheral neuropathy, and neurological disorders may present themselves. Some researchers suggest that diseases attributed to “old age,” such as cognitive decline, loss of mobility and balance, and memory loss, are sometimes synonymous with vitamin B12 deficiency. In the case of neurological symptoms, cumulative damage due to long-standing deficiency may be irreversible. This impresses the importance of early diagnosis and ensuring adequate blood levels.
Causes of Vitamin B12 Deficiency
Knowing some of the primary causes of B12 deficiency can help inform us on how to best prevent or avoid deficiencies. A few are:
Inadequate Dietary Intake
Vitamin B12 can only be consumed through animal foods and supplements. Children also are at high risk due to inadequate dietary consumption and lower bodily reserves, despite higher requirements per food calorie. Gastritis, stomach abnormalities/surgeries, or hereditary traits may be to blame for
Absent or Low Stomach Hydrochloric Acid
Sufficient HCl is essential, independent of intrinsic factor secretion, for cleaving B12 from carrier proteins in food. This is thought to be a major cause of deficiency in the elderly, who generally suffer from low stomach acid.
Other causes include:
- Celiac disease leading to small intestine damage causing impaired absorption of vitamin B12, which is principally absorbed in the ileum.
- Bad bacteria overgrowth in the small intestine, which some research shows can cause malabsorption of B12.
- Diabetes medication Metformin may interfere with absorption of B12.
- Parasitic infection, such as Giardiasis, can cause leaching of the vitamin leading to deficiency.
- Genetic factors such as deficiency in the MTHFR gene, transcobalamin (another type of B12), etc.
- Excessive alcohol intake.
Symptoms of Vitamin B12 Deficiency
Knowing some of the common symptoms, mild and severe, of B12 deficiency can help inform us on how to best prevent or avoid deficiencies. Since it can take years to manifest a clinical deficiency as measured by blood testing, it’s important to note that signs of deficiency can remain silent for some time as bodily B12 levels are slowly depleted. A few are:
- Pernicious anemia, specifically megaloblastic anemia, which is a second type of anemia that causes dysfunction of the bone marrow’s ability to manufacture red blood cells.
- Neurological impairments such as depression, confusion, disorientation, schizophrenia, ADHD.
- Memory loss, Alzheimer’s, Parkinson’s, brain fog, cognitive decline, brain shrinkage.
- Increased fatigue.
- Peripheral neuropathy.
- Sexual dysfunction including low libido, low sperm count, ED, low sex hormone levels.
- Paresthesia (tingling sensation in hands, feet, limbs).
- Spinal cord/myelin sheath degeneration.
- Bowel/urinary incontinence.
- Itchy skin.
Vitamin B12 is an incredibly important and integral essential nutrient in human health, especially all manner of neurological health and red blood cell formation. When deficiencies occur in other nutrients, symptoms or disease processes can be reversed with repletion. Vitamin B12 is so vital and important in brain and nervous system function, that often the damage from deficiency is permanent and irreversible. Daily supplementation that ensures optimal vitamin B12 intake that far exceeds the minuscule daily requirements as set by the government and scientific health bodies is ideal.