Everything you need to know about Vitamin B12

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Hello and welcome to today?s post about Vitamin B12!

This is a long post. So grab a glass of your favorite beverage, sit back and enjoy the whole thing if you’d like.

For those of you who only want to know about a specific detail, take advantage of the table below. It is clickable and will bring you right to the section you want to see!

What is vitamin b12?

Also called cobalamin, this vitamin is water-soluble and provides a key role in the normal function of the human brain, nervous system and the formation of blood.

It is one of the eight B vitamins and contains the mineral cobalt. Structurally, it is the most complicated vitamin in our body! It is also the largest.

What does it do for the body?

This vitamin helps the body synthesize DNA and red blood cells. It works together other nutrients like folate to accomplish this.

It?s also involved with the production of the ?myelin sheath?, which is a barrier the body creates around nerves which helps protect them and help your nerves fire correctly.

When the bodily is properly fueled with vitamins like B12 the brain runs smoothly. But when we become deficient of this vitamin we run into neurological problems like fatigue, lethergy, general weakness and psychiatric problems.

All about deficiency.

B12 deficiency is a common issue thats experienced by many people in the modern world. It affects all ages groups, from youth to the elderly. Due to it?s commonality, the causes, effects and diagnosis of deficiency are well established.

Yet even though it is a well known issue, there are still tens of thousands of people who have undiagnosed cases.

Most people do not think of a vitamin deficiency when they start experiencing health symptoms, and many healthcare practitioners don?t think to look for it either.

It is estimated that 40% of people from the ages of 26 to 83 have blood levels in the low end of the normal range (http://www.ars.usda.gov/is/pr/2000/000802.htm). Levels this low commonly result in neurological symptoms. 9% are likely to have outright deficiency, and 16% with near deficiency.

Elderly people suffering from B12 deficiency are likely to experience enhanced symptoms of aging including memory loss, cognitive decline and decreased mobility.

There are four distinct stages of deficiency:

  1. declining blood levels of the vitamin
  2. low cellular concentration of the vitamin
  3. increased blood levels of homocysteine and decreased rate of DNA synthesis
  4. Macrocytic anemia

So, why are people unaware of their deficiency?

Putting aside outright neglect of looking after one’s health, there are two main reasons that people are in the dark about this issue:

  1. b12 levels are rarely tested by physicians. Most lab tests don?t check for b12 levels and doctors rarely add on extra testing unless prompted.
  2. When tested, many laboratory tests will show results on the low end of ?normal?, when in fact they are deficient.

In the US, ?Normal? levels are considered to be between 200pg/mL and 350 pg/mL (determined by general established health authority consensus.) Yet experts who specialize in treating deficient conditions often recommend treating all patients who have levels below 450 pg/mL.

To contrast, in Europe and Japan 550 pg/mL or lower is considered deficient.

Why is deficiency so common?

Often times people become deficient for one of two reasons:

  1. poor diet / dietary restrictions.
  2. malabsorption

1.) Diet

b12 is found in animal products. This is because the compound is created by bacteria in an animal’s gut. (It?s the only vitamin that contains the element cobalt, which we can?t obtain it from plants or sunlight.)

Many people who eat a animal product rich diet will get enough of the vitamin in their day to day diet.

In a typical Western diet a person will obtain 5 to 15mcg (micrograms) of the vitamin daily. This exceeds the recommended daily intake of 2mcg.

Examples of foods very high in b12:

  • liver, offal, organ meats
  • seafood, especially shellfish/mollusks
  • eggs
  • ruminants. ie. lamb, beef, moose, veal
  • chicken/duck
  • dairy products

Those highest at risk for deficiency have low amounts of these foods in their diet over a long period of time.

Note: for vegans and vegetarians:

Even though b12 is only produced in animal?s this does not mean you should be avoiding this essential nutrient!?Studies have shown that up to 80% of long term vegans and 50% of long-term vegetarians are deficient.

A common belief in plant-based diet circles is that you can get b12 from plant sources like seaweed and fermented products. But the nutrients found in these foods are actually analogs of b12, called cobamides. And these analogs actually make it harder for you to absorb real b12 because they block intake.

Blue green algae, a common supplemental form of b12 actually contains a pseudovitamin form that is not active for humans.

There are vegan options for supplementing this vitamin into your plant-based diet. These supplements rely on culturing the bacteria that produce b12. Below are some trusted, high quality vegan/vegetarian approved supplements:

2.) Malabsorption

The body needs to be functioning well in order to properly absorb vitamins. For b12, there are numerous disorders which can limit absorption.

  • gut / intestinal dysbiosis
  • leaky gut (http://scdlifestyle.com/2010/03/the-scd-diet-and-leaky-gut-syndrome)
  • inflammation of the gut
  • low stomach acid
  • gastritis
  • autoimmune anemia (pernicious)
  • drugs, like alcohol
  • medications (acid-suppressors, proton-pump inhibitors)
  • intestinal surgery
  • bacteria overgrowth
  • parasites
  • kidney disease
  • liver disease
  • pancreas disease
  • stomach disease
  • thyroid disease

Clearly, it?s not just whether or not you are eating enough b12 in your diet. It?s whether or not you are absorbing it!

The most well established disorder causing malabsorption is pernicious anemia. This is an autoimmune disease that stunts the gastric parietal cells. When these cells are destroyed the body has limited ability to absorb b12. This issue can be resolved with proper oral replacement therapy.

But as you can see from the list above, there can be many reasons for malabsorption.


For proper functioning, the levels below outline the recommended daily intake of b12 (numbers from the institute of medicine)

  • Infants 0 to 6 months 0.4 mcg
  • Infants 7 to12 months 0.5 mcg
  • Babies/toddlers 1 to 3 years 0.9 mcg
  • Children 4-8 years 1.2 mcg
  • Children 9 to 13 years 1.8 mcg
  • Teens and adults14+ years 2.4 mcg
  • Pregnant mothers 2.6 mcg
  • Lactating (breastfeeding) mothers 2.8 mcg

Your typical adult with normal gastrointestinal functioning is able to absorb about 50% of bioavailable vitamin b12 through diet.

The way your body absorbs vitamin b12 is complex – bioavailability is more challenging for us with this nutrient than many others.

Though foods will provide forms that are more readily absorbed than others.

For example:

  • Fish provides an average of 42% absorption rates.
  • Sheep meat between 60% and 90%.
  • Eggs have a much lower bioavailability of around 4-9% absorption.
  • Beef from 40% to 89%
  • Chicken from 61 to 66 percent.
  • Milk / cheese / dairy products from 55 to 65 percent

While meat eaters will have an easier time filling their daily allowances, vegetarians and vegans should put high emphasis on eating the following types of foods to insure they are getting adequate amounts of the vitamin levels.

For vegetarians:

  • Low fat milk (8oz.) = 1.4 micrograms b12
  • cottage cheese = 1.3 micrograms
  • ricotta cheese = 0.85 micrograms
  • large cooked eggs = 0.65 micrograms

For vegans:

  • Fortified cereals = 6 micrograms per 8 oz serving (avg.)
  • fortified meat substitutes (ex. Morning Star burger, Chink?n Strips) 9 micrograms and 0.85 micrograms.
  • Soy milk = 1 microgram per 8 oz (avg.)

For non-meat forms, remember that absorption rates are lower than nutrient amounts in the food. So you will have to eat multiple servings to each the 2.5 microgram daily allowance.

Methods of administration

Apart from diet, there are three main ways to administer vitamin b12. Supplementation through these routes is necessary in the case of malabsorption, disease and/or dietary limitations.

  • Oral route
  • Nasal route
  • Parenteral route (intravenous)

Oral route

In recent decades the medical community has discovered that oral (sublingual) administration of b12 is an effective way to address serum level deficiencies of the vitamin.

The oral route of administration has been shown to increase and stabilize blood levels just as effectively as intramuscular injections.

Oral route, as well as being effective in treatment, is also the most enjoyable and convenient way to supplement.?One can either choose to dissolve a lozenge sublingually, or spray a solution under their tounge and hold it for absorption.

Oral forms that are available over the counter typically come as:

  • Tablets (100,500,1,000 or 5,000 micrograms
  • Lozenges (50,100,250, 500 or 1,000 micrograms

Nasal Route (transnasal)

This form of administration has proven to be an effective, low cost and low hassle way to get b12 into your system.

Oral therapy is not always suitable because some patients lack the ability to absorb b12 sublingually.

For these patients nasal administration is more appropriate. When given intra-nasaly the delivery of the drug goes straight into systemic circulation resulting in improved absorption and effectiveness.

Those who should look for a nasal route option lack intrinsic factors of absorption, conditions associated with gastric atrophy, infestations with parasites i.e tape worm etc?

Ask your doctor if you think you might need this form.

You can find spray forms of nasal b12 fairly easily over the counter. And it comes in some of the more desirable forms of the vitamin in these products.

Parenteral route (intravenous)

This is the traditional treatment for treating deficiency. They come in the form of intramuscular injections where a clinician injects high amounts of the vitamin into the muscle and bloodstream.

Until recent decades this was the main form of vitamin therapy used for b12 deficiency. This is partly because most clinicians were unaware of the effectiveness of orally administered therapy.

Oral treatment is more desirable because it removes the pain of having injections and the cost of frequent trips to the doctor for new injections.

As oral treatment is continued to be shown effective, it is likely that intramuscular administration will become far less common.

The Four main forms of supplemental vitamin b12

1.) Cobamamide

Cobamamide is an active form of vitamin b12. This means that it is readily digested by the body. It is also known as adenosylcobalamin and dibencozide.

As a nutritional supplement cobamamide is available in supplement form, but not in injectable form.

2.) cyanocobalamin

The majority of b12 supplements contain cyanocobalamin as the active ingredient. It is the most widely manufactured because is the easiest to produce and purify, as well as being the most air stable form available.

It is available in oral, nasal and injectible form.

Cyanocobalamin is a man made ?vitamer? of b12. Vitamer means it is not itself an active form of b12, but the body is capable of breaking it down into an active form of the nutrient.

In the case of cyanocobalamin, cyanide molecules are attached to the nutrient. The body then removes and detoxifies the cyanide and digests the resulting bioactive form – methylcobalamin.

Some people have reservations about the cyanide in this form of the nutrient. While cyanide is toxic at moderate levels, the amount freed up by the body in digestion of cyanocobalamin is very negligible and should cause no harm.

Regardless, it is recommended that those with malfunctioning kidneys or a history of cyanide poisoning should not take cyanocobalamin.

Side effects: Oral use of cyanocobalamin may lead to allergic reactions in patients. Inflammatory reactive conditions such as hives, difficulty breathing, swelling of the face, lips, tongue or throat have been reported.

Less serious side effects include headache, nausea, upset stomach, diarrhea, joint pain, itching or rash.

3.) Methylcobalamin

Methylcobalamin is a common and well absorbed form of b12. It is a readily digested cobalamin with added properties. Methylcobalamin is equivalent physiologically to vitamin b12. This makes it an effective, direct route vitamin for supplementation.

It?s similar to cyanocobalamin, but it differs from cyanocobalamin because a methyl group of molecules is bound to cobalamin instead of cyanide molecules being bound.

This makes it more desirable in many cases than cyanocobalamin because no toxic cyanide is released during digestion.

4.) Hydroxocobalamin

While methylcobalamin is considered a better choice than cyanocobalamin, hydroxocobalamin trumps both.


  • Hydroxocobalamin binds better and more extensively to the body?s plasma proteins and has a longer half life in the body than cyanocobalamin.
  • Additionally, methylcobalamin has a high susceptibility to degradation. In fact, it is the least stable among all derivitaves of vitamin b12. Hydroxobalamin, on the other hand, is one of the most stable forms available.

Hydroxocobalamin is primarily available in supplemental form as a oral lozenge that dissolves in your mouth.

Recommended b12 Supplements

Many practitioners recommend cyanocobalamin as the go-to supplement. This is often because they are unaware of higher quality alternatives (Methyl and Hydroxo forms.)

Below are some of the best forms of b12 on the market – and i?ll be sticking to the more stable / higher absorbed varieties (from very reputable brands.)

Oral (lozenge):



Thanks for reading this post on b-12.

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