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B12 Supplement for Adults


A vitamin B12 supplement is formulated to contain a dosage of vitamin B12 that may help an individual to meet their health and wellness needs. Vitamin B12, also known as cobalamin or choline, is important to the structural integrity of cell membranes, methyl metabolism, cellular transmission, and signalling in the central nervous system. It supports blood fat (lipid) and cholesterol transport and metabolism.(1) Vitamin B12 is an organometallic compound that contains the mineral cobalt. It is also one of the eight essential B vitamins.. Like all B vitamins, B12 is water soluble and is either a coenzyme that helps move metabolic processes forward towards completion or acts as a precursor that is necessary to begin a metabolic process.(2)

The molecular structure of B12 is considered to be relatively large and is found in several forms depending on the other molecules that are present.(3) This includes cyanide that when bound to cobalamin becomes cyanocobalamin. When humans ingest cyanocobalamin, it must undergo detoxification in the liver to remove the cyanide.(4) Cobalamin activates when it bonds with a methyl donor molecule, becoming the active form of B12, methylcobalamin. A vitamin B12 supplement offering this active form is considered ideal for supplementation as it is more bioavailable and reduces exposure to cyanide.

A vitamin B12 supplement seeks to support many healthy functions in the body, including:

  • Energy levels
  • Skin tone
  • Digestion
  • Abdominal comfort
  • Healthy weight management
  • Sensory touch in hands and feet
  • Cognition
  • Memory, focus, and clarity
  • Nervous system function
  • Mood and behavior
  • Stress and frustration response
  • Cardiovascular rhythm
  • Dental health
  • Appetite
  • Adrenal function
  • Hormonal balance
  • Enzyme production
  • DNA synthesis
  • Fetal development

Vitamin B12 is relatively well understood in scientific circles. Research into its many functions including how it works alongside other vitamins, has provided valuable insights into its role in maintaining health and wellness in the body. But it was not that long ago that we didn’t know about the importance of consuming enough vitamins to meet daily dietary needs.

The History of Vitamins


Before the 1900s, nutritional deficiencies that resulted in illness and death were common, especially among sailors and those that lived in colder climates.(5)(6) Diets consisting heavily on grains or salted meats caused people to have inadequate nutrition that could have been balanced with fruits and vegetables. But even if they had access to a variety of healthy foods, people lacked an understanding of the role that nutrients played in preventing nutritional deficiencies, illness, and death.

In the latter half of the 1800s, scientists first theorized the existence of germs. At first, these scientists attempted to link this newfound knowledge about pathogens to the conditions that actually resulted from nutritional deficiencies. A few decades later, in 1911, the Polish biochemist Casimir Funk made great strides by proposing the existence of an unknown organic substance that he named "vitamines."(7)

Vitamines combines "vital" with "amine," where amine is a nitrogen-containing group in organic molecules. He suggested these vitamines were the key to reversing and preventing conditions that were the result of inadequate nutrition. While it was later discovered that not all vitamines possess amine structures, the popularity of the term had already spread through scientific circles and the public, so only the "e" was dropped.

Cobalamin: The Last B Vitamin

In 1855, the English physician Thomas Addison wrote about symptoms caused by an unknown ailment that included “shortness of breath, jaundice, weight loss, and muscle spasms.”(8) This condition become known as “Addison's anemia.”

At this time, anemia was understood as a condition related to a blood disorder. In the case of Addison’s anemia, later renamed pernicious anemia in 1872 by German physician Anton Biermer, the blood disorder is “characterized by the presence of large, immature, nucleated cells (megaloblasts) that are forerunners of red blood cells.”(9) In effect, a person’s body no longer produces enough mature red blood cells, and the body is unable to transport oxygen, vitamins, and immune system factors.

In 1926, physicians from Harvard University found that eating half a pound of liver each day would stop the onset of pernicious anemia.(10) Moving forward, researchers worked to identify the substance in the liver that prevented pernicious anemia. Human and animal models were used to evaluate the effects of liver extract, but this process was time consuming.

A few years later, researchers at Columbia University learned about Mary Shorb, a former microbiologist with the U.S. Department of Agriculture, who had identified a bacterium that responded to the liver extract. Her research showed liver extracts that were pinkish in color had the greatest effect on bacteria, as these bacteria would absorb the pinkish hue. As theorized, in 1947, vitamin B12 was eventually isolated and found to appear as tiny, red crystals.

Vitamin B12 is the last B vitamin to have been discovered that is essential to human health or that is not produced inside the body. In total, there are eight B vitamins that, when together, are known as a B vitamin complex. Other compounds have been labeled as B vitamins due to the similar structures, but these compounds are not necessary to human health.


Potential Vitamin B12 Benefits


Like all B vitamins, vitamin B12 is not stored for extended periods of time inside the body. Once absorbed through the digestive system, vitamin B12 moves through the bloodstream to reach different areas of the body that require it to function. Eventually, all blood moves through the liver and undergoes detoxification. Vitamins, metabolic waste, free radicals, pathogens, and other compounds are filtered out into the bowels or kidneys during this process. Because of this, resupplying the body with vitamins is important to help prevent nutritional deficiencies and provide support for many essential functions in the body.

Cardiovascular Health

Vitamin B12 is crucial to the synthesis of amino acids that help to form structures or support various functions in the body.(11) Vitamin B12 works with vitamin B9 and B6 to help recycle the amino acid homocysteine (a sulfur-containing element) into methionine, and the conversion of homocysteine into cysteine. When B vitamins are found in lower levels or are missing in the body, a condition referred to as a nutritional deficiency anemia occurs. When this happens, homocysteine levels in the blood increases and “promotes atherosclerosis through increased oxidant stress, impaired endothelial function, and induction of thrombosis." Studies suggest that elevated plasma homocysteine concentrations increase risk of cardiovascular disease by two fold, and to a lesser degree, the risk of cerebrovascular disease.(12)(13)

Blood, Immune Factors, Hormones, and DNA

Vitamin B12 is essential to the synthesis of vitamin B9 (folate) from its original form, known as methyltetrahydrofolateinto L-methylfolate, the active form of folate.(14) Folate is essential for the function of iron, which helps produce hemoglobin and transport oxygen in the body, and adenosylmethionine (SAMe), an immune factor that supports immune system functions and a healthy mood and behavior.(15)

Folate is also essential in the “downregulation of the synthesis of proteins and the nucleotides required for DNA/RNA synthesis.” This biological function is considered especially important for “rapidly dividing tissue,” including tissue that forms during fetal development. Folate also supports the synthesis and regeneration of tetrahydrobiopterin, a cofactor for the enzymes that convert compounds into serotonin, melatonin, dopamine, noadrenaline, adrenaline, and nitric oxide. (16) These hormones help to regulate function throughout the entire body.

Cognition During Aging

Vitamin B12 is being studied for its potential role in how cognitive disorders progress.(17) As mentioned earlier, vitamin B12 is essential for the conversion of homocysteine to methionine. Currently, it is hypothesized that homocysteine may contribute to the development of “mood disorders, and dementias, including Alzheimer's disease and vascular dementia in elderly people.”(18)

Currently, observational studies are investigating how homocysteine may contribute to “oxidative stress, the inhibition of methylation reactions, increased damage to DNA and dysregulation of its repair, and direct and indirect neurotoxicity leading to cell death and apoptosis.”(19) However, several research papers note that there is an inherent difficulty in evaluating the effect of vitamin B12 when all eight B vitamins may contribute to the function of the brain during normal aging. How each B vitamin reacts to the other vitamins, DNA, tissue, and other factors is not entirely understood at this point.

Vitamin B12 Dosing

When looking at the Recommended Dietary Allowances (RDAs) of vitamin B12, the suggested intake levels represent the amount of vitamin B12 that is sufficient for at least 97% of individuals.(20) Daily requirements may depend on individual health, prescriptions, or OTC medications.

Recommended Dietary Allowances For Vitamin B12


Tolerable Upper Intake Levels For Vitamin B12

There is insufficient evidence to set tolerable upper intake levels for vitamin B12 from food sources or supplements. If any changes to individual health occur when taking an amount of vitamin B12 above the recommended dietary allowances, immediately consult with a doctor.

B12 Deficiencies

Vegan, vegetarian, or gluten-sensitive diets are most at risk of a vitamin B12 deficiency.(21) Dietary choices will affect the type and quantity of vitamins an individual receives. Some foods that may be ideal for meeting daily dietary requirement includes:

  • Clams
  • Organ meats (liver, kidney)
  • Fortified cereal
  • Fish (trout, salmon, tuna, etc.)
  • Beef, pork, poultry
  • Greek yogurt
  • Low-fat milk
  • Ham
  • Eggs
  • Cheese

Vitamin B12 is bound to protein in food. When B12 comes in contact with hydrochloric acid and gastric protease in the stomach it separates and becomes available for absorption. When found as free vitamin B12 (not bound to protein) in fortified foods and supplements, the first 56% of 1 mcg is readily absorbed. Additional absorption occurs but decreases beyond 2 mcg, or as a result of other factors.

Vitamin B12 content might not be labeled on food. The FDA does not require food labels to list vitamin B12 content unless food has been fortified with this nutrient. If food is not enough to meet daily recommended levels of nutrients, then supplementation may be ideal.

Warnings and Interactions


Anti-seizure medications, chemotherapy medications, colchicine, bile acid sequestrants, H2 blockers, Metformin, proton pump inhibitors, and antibiotics may reduce your levels of B12. People taking these medications should ask their doctor prior to taking a vitamin B12 supplement. If you take tetracycline (acne medication) you should stop taking a B12 supplement unless otherwise directed by a medical practitioner.(22)

Taking a high dose of folic acid is known to hide a vitamin B12 deficiency. Avoid taking more than 800 mcg of folic acid unless instructed by a medical practitioner. Individuals with red blood cell disorders may not benefit from vitamin B12. A vitamin B12 supplement may also interact with specific disorders of the eye, causing severe damage to the optic nerve.

Not all vitamin B12 supplements are formulated the same way, with some supplements containing additional vitamins, herbs, and extracts that might alter the effect of vitamins in the body. If taking another supplement while using a vitamin B12 supplement, unexpected interactions can occur.

Begin a Vitamin B12 Supplement Regimen


Vitamin B12 supplements can help to fill nutritional gaps and help individuals meet daily dietary needs. Vitamin B12 supplements are available for adults and children in the form of capsules, chewables, sprays, liquids, or gummies; can also be found in multivitamins and B complex supplements; plus exercise aids such as energy bars and powdered drink mixes. A medical practitioner may be able to administer a vitamin B12 injection with a higher dose if needed due to digestive challenges, anemia, or other negative health states.

The understanding of nutrition has changed a lot in human history. Today, it is known that carbohydrates, proteins, fats, vitamins, and minerals will provide the body with the compounds it needs to function normally. Even if certain foods are not readily available, modern innovations such as supplementation makes it easier than ever to meet dietary needs. Find a vitamin B12 supplement that works for your and see if it makes a difference in your life.


  1. https://www.nap.edu/read/6015/chapter/14
  2. https://www.rose-hulman.edu/~brandt/Chem330/Vitamin.pdf
  3. https://examine.com/supplements/vitamin-b12/
  4. http://www.b12-vitamin.com/types/
  5. https://dash.harvard.edu/bitstream/handle/1/8852139/Mayberry.html?sequence=2
  6. http://healthandfitnesshistory.com/ancient-nutrition/medieval-european-nutrition/
  7. https://www.nobelprize.org/nobel_prizes/themes/medicine/carpenter/
  8. http://www.animalresearch.info/en/medical-advances/timeline/pernicious-anaemia/
  9. https://www.medicinenet.com/script/main/art.asp?articlekey=7196
  10. https://www.acs.org/content/acs/en/education/whatischemistry/landmarks/vitamin-b-complex.html
  11. https://www.hsph.harvard.edu/nutritionsource/vitamin-b
  12. https://www.mayoclinic.org/diseases-conditions/vitamin-deficiency-anemia/symptoms-causes/dxc-20265323
  13. https://www.ncbi.nlm.nih.gov/pubmed/16510043
  14. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4772032/
  15. https://www.ncbi.nlm.nih.gov/pubmed/15671130
  16. https://www.ncbi.nlm.nih.gov/pubmed/16387296
  17. https://www.ncbi.nlm.nih.gov/pubmed/17052662
  18. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4918681/
  19. https://www.ncbi.nlm.nih.gov/pubmed/18709889
  20. https://ods.od.nih.gov/factsheets/VitaminB6-HealthProfessional/
  21. https://www.vegansociety.com/resources/nutrition-and-health/nutrients/vitamin-b12/what-every-vegan-should-know-about-vitamin-b12
  22. http://www.umm.edu/health/medical/altmed/supplement/vitamin-b12-cobalamin