Vitamin B12 Overview

Vitamin B12 Overview: B12 is an essential vitamin in human nutrition. Because our bodies don’t naturally produce it, we must acquire it from our diet or take a supplement. Commonly found in meat and dairy products, B12 is scarce in plants, which is why vegans and vegetarians often need to supplement with B12 to avoid developing a deficiency. The following content outlines the role of B12 in human nutrition, results of a B12 deficiency and factors leading to it, as well as proper form and dosage of B12.

B12 in Human Nutrition:

Vitamin B12 carries many responsibilities in human nutrition because it’s involved in various cellular functions and the metabolism of important nutrients. Its roles include:

Proper production and synthesis of red blood cells and DNA

Metabolism of fatty acids, carbohydrates and proteins

Proper function of nervous system tissues and cells

Proper function of bone marrow cells

Proper function of gastrointestinal tract cells

B12 Deficiency:

Vitamin B12 deficiency is less common in diets rich in animal proteins and meat, but is more common in vegan and vegetarian diets. Symptoms of a B12 deficiency may include one or more of the following:


Damaged nervous system tissues

A compromise in mental health, sometimes leading to cognitive impairment, depression, and in severe cases, psychosis

Early on set Alzheimer’s Disease

Causes of B12 Deficiency:

Partial removal of the small intestine, leading to malabsorption

A diet low in meat and animal proteins

Adverse effects of certain medications

Malabsorption due to various gatrointestinal issues

Forms of B12:

Methylcobalamin is probably the best form of B12 for supplementation. It is chemically the same as B12 and can be used orally to prevent B12 deficiency. Because B12 is sensitive to acids and alkalis, it typically comes in the form of a lozenge that is placed beneath the tongue. This helps it absorb into the bloodstream through the gums without being broken down in the stomach or other parts of the digestive tract. Because it can readily enter the bloodstream this way, it is easily used by the body (namely the liver and nervous system components) and is adequately stored.

Another form includes cyanocobalamin, which is a common source found in most stores and pharmacies. Cyanobalamin isn’t as wellabsorbed or readily stored as methylcobalamin, and it usually requires a higher dosage. Though these factors put cyanobalamin at a disadvantage, it is still often the initial form of B12 that is recommended to patients, simply due to its prevalence and attainability.

Hydroxocobalamin is another source of vitamin B12. Often in the form of an injetion, hydroxocobalamin can be used to treat B12 deficiencies as well as cyanide poisoning. Because this form is often injected, it is not favorable for daily supplementation, despite its effectiveness.

Food sources of vitamin B12 include: Shellfish (84 mcg/3oz), beef & organ meats (70 mcg/3oz), fish (52 mcg/3oz depending on the species), dairy/milk/yogurt (1.51.0 mcg/8oz), eggs (0.5 mcg/each), poultry (0.3 mcg/3 oz)

Recommended Dosage:

Recommended dosage varies greatly, from 1002,000 micrograms/day, depending on the form of B12 and if one has a B12 deficiency. A recommended daily dose of methylcobalamin, for example, is 1000mcg, which is probably adequate for a person who occasionally consumes meat and/or dairy products, but wants to ensure that they have healthy B12 levels. Those who do not consume meat or animal protein may want to increase their daily dose of B12. I highly recommend blood tests if you think you might have a deficiency. Otherwise, follow the instructions on the supplement container, or ask your doctor if you have additional questions.

There have been conflicting results from studies trying to determine if certain forms of algae are viable sources of B12. Some forms of seaweed (nori and spirulina), do not seem to contain bioavailable forms of B12, however there may be levels of bioavailable B12 in bluegreen algae. Until the viability of B12 in these sources can be determined, I don’t think they should be recommended for daily supplementation for those seeking alternatives to animal proteins.

For best results, avoid taking vitamin C within an hour of b12. Also avoid having alcohol and caffeine, as these substances can interfere with the absorption of this vitamin

Sulfur (MSM), selenium and calcium are okay when paired with this vitamin, in addition to other B vitamins

Brands I recommend: Seeking Health Active B12/Folinic Acid (800mcg Folinic Acid/1000mcg B12)*Note: B12 and Folate (Folic Acid) have very similar functions, and work best when taken together. B12 is sensitive to light. Store in a cool, dark place.