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All You Need to Know About Vitamin B-12

Posted By G Monkie On January 29, 2009 @ 7:00 am In Fitness/Diet,G Living | No Comments

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All You Need to Know About Vitamin B-12

Vitamin B-12 is one of the eight vitamins in the B-complex group. It plays a very important role in a number of metabolic functions in our body.

Generally, B-complex group vitamins are water-soluble in nature, meaning they easily dissolve in water and other body fluids. Because of this, the B-complex group vitamins are not retained in our body. They are removed from our system from time to time. So a daily intake of the water-soluble vitamins is essential.

Unlike other water-soluble vitamins, vitamin B-12 can be stored in our body, although in small quantities. The amount of vitamin B-12 stored in our body is sufficient for a few years, and so its deficiency is not very common to occur.

Vitamin B-12 is the general name of a group of chemically-related compounds called cobalamins that have similar vitamin activity. Though the basic structure is the same, there are different forms with minor variations.

How and Where is it Synthesized?

Vitamin B-12 is not synthesized by plants or animals, but is synthesized by microorganisms like bacteria, yeasts, molds, and algae. This is because the enzymes required for the synthesis of this vitamin appears to be present only in microorganisms. Plants and animals lack in these enzymes.

The basic structure of vitamin B-12 is synthesized ONLY by the microorganisms and then it can be converted to other physiological forms in our body.

Just like hemoglobin in our blood has a central iron atom and chlorophyll in leaves has a central magnesium atom, vitamin B-12 has a central cobalt atom in its structure. So, cobalt is an essential mineral in the synthesis of vitamin B-12.

Food Sources

Vitamin B-12 is present in significant amounts only in animals and animal-based products. Examples of this are calf liver, beef, lamb, salmon, cod, shrimp, snapper, eggs, milk, and yoghurt.

Though it is present in some plants, the amount present is very small and is not sufficient enough to meet the daily requirements for humans.

Examples of this are sea plants, blue-green algae, yeasts, etc.

Animals and plants do NOT synthesize this vitamin. But the vitamin B-12 content in these foods depends on their ability to store and retain it in their body. Because animals retain it better than plants, animal foods are better sources of this vitamin.

Raw/Vegan Sources

There are no proven raw/vegan food sources that supply sufficient amounts of this vitamin to meet the daily requirements.

So, if you are a raw foodist or a vegan, it is recommended to take a dietary supplement of vitamin B-12.

Daily Requirement

Vitamin B-12 is required in very small quantities, generally in micrograms (whereas most other vitamins are required in milligrams or grams) but it does not mean it is any less important than other vitamins.

Children (1-8 years): 0.9-1.2 micrograms
Children (8-13 years): 1.8 micrograms
Adult males: 2.4 micrograms
Adult females: 2.4 micrograms
Pregnant females: 2.6 micrograms
Breast-feeding females: 2.8 micrograms


Vitamin B-12 functions as a cofactor to enzymes in many important metabolic reactions, which are vital to the following functions.

1. Proper Cell Division:

This vitamin is required for mitotic division of DNA. In its absence, the DNA is not properly divided, in turn affecting the cell division.

2. Synthesis of Proper RBCs:

Because vitamin B-12 is essential for cell division, its deficiency also results in improperly divided, oversized, poorly shaped RBCs, which do not function properly. So, the transfer of respiratory gases and nutrients is not performed properly by the RBCs, resulting in a type of anemia called pernicious anemia. Though it is blamed on the deficiency of vitamin B-12, it is actually due to the absence of the intrinsic factor that is required for proper utilization of vitamin B-12.

3. Keep the Nerve Cell Structure Intact:

Nerve cells or neurons have a protective covering around them called myelin sheath. This myelin sheath ensures the proper transfer of impulses from brain to cells. In vitamin B-12 deficiency, the myelin sheath is not properly formed, resulting in neurological disorders.

4. Metabolism of Carbohydrates, Proteins and Fats:

Vitamin B-12 is necessary for the proper utilization of carbohydrates, proteins and fats. So in its deficiency, though carbohydrates, proteins and fats are present, they are not fully utilized for various functions in the body.

Deficiency Symptoms

There are a number of symptoms that indicate the deficiency of vitamin B-12, although it is not the only factor that can cause these symptoms. Sometimes, there are different factors that contribute these conditions along with vitamin B-12. Here are some most common symptoms that indicate a deficiency of vitamin B-12:

Neurological Symptoms:

1. Nervousness
2. Depression
3. Tingling and numbness in feet
4. Memory problems

General Symptoms:

1. Anemia
2. Paleness
3. Sore tongue
4. Fatigue
5. Palpitations
6. Weakness

Factors that Affect its Function

Vitamin B-12 needs other factors for it to function effectively. And some other factors can reduce its efficiency. Although there may be other factors, these are some of the common factors that affect the proper functioning of vitamin B-12.

1. Intrinsic Factor:

This is a protein secreted in the stomach by a certain types of cells called parietal cells. This intrinsic factor binds with vitamin B-12 in the stomach and both are absorbed into the blood. The presence of intrinsic factor is very important for the proper functioning of vitamin B-12. So, even if vitamin B-12 is consumed in sufficient amounts, if intrinsic factor is not properly secreted in the stomach, vitamin B-12 cannot be utilized.

2. Vegan Diet:

As there are no proven sources of plant based foods that provide sufficient amounts of vitamin B-12, consumption of a strict vegan diet can result in vitamin B-12 deficiency. It is the same with a raw vegan diet.

3. Excess Consumption of Meat:

Excess consumption of meat, as in a standard western diet can also decrease the binding of dietary vitamin B-12 to intrinsic factor and its utilization.

4. Digestive Disorders:

In digestive disorders where stomach cells are destroyed or the lining of the stomach is inflamed, intrinsic factor is not secreted and it leads to a non-utilization of dietary vitamin B-12. Disorders of the intestine also inhibit the absorption of vitamin B-12 bound to intrinsic factor.

5. Over-the Counter Drugs:

OTC drugs like antacids decrease the secretion of hydrochloric acid in the stomach. The acidity is very important to release the vitamin B-12 bound to protein in the foods. Unless vitamin B-12 is released, it cannot bid to intrinsic factor. There are some other drugs also that affect the functioning of this vitamin.

Dietary Supplements

Dietary supplements of vitamin B-12 are available in the form of cyanocobalamin, hydroxocobalamin, methylcobalamin, etc. Cyanocobalamin is the most common type of vitamin B-12 in the dietary supplements. This is not a natural form but is widely used for its stability and lower cost of production. Once absorbed, it is then converted to other physiological forms in our body.

The dietary supplements are available as – oral supplements, sublingual supplements, injections and intranasal supplements.

Of the different supplements available, methycobalamin form of this vitamin taken sublingually is believed to be the best form of taking this supplement.

How are Dietary Supplements Synthesized?

Dietary supplements are synthesized in the laboratories from various strains of bacteria and molds. Selected organisms are genetically engineered and grown under special conditions to enhance the yield of vitamin B-12. Then these microorganisms are fermented and vitamin B-12 produced in large scales in laboratories.

The vitamin B-12 thus produced is then purified to remove any unnecessary compounds that may have formed as a byproduct. During the purification process, cyanide is picked up by the cobalamin and cyanocobalamin is formed, which is chemically stable.

Something to Think About

As noted above, dietary supplements of vitamin B-12 are produced in the laboratories using genetically modified microorganisms. Then they are fermented and purified.

Because they go through all these processes, they are not ‘raw’ or ‘natural’ in ANY way. They are processed just like any other processed foods.

Now, here is something I would like you to think about. There is nothing wrong in thinking, analyzing and deciding for yourself what is good for you.

If we can have these genetically modified, processed and purified vitamin B-12 as dietary supplements, why not consume food sources rich in vitamin B-12 that are completely natural and unprocessed?

Wondering What They Are?

Well, think about it. How about fresh, natural, organic, free range (and certainly raw, if you like) eggs or milk or homemade yoghurt? There is no processing involved, there is no animal cruelty involved, and there are no additives, preservatives, or stabilizers involved.

These foods, although not excellent sources of vitamin B-12, are quite good sources of this vitamin.

The decision to what to put into your body is totally yours. If you do not want to consume animal products, it is entirely up to you.

Eat healthy and live happy,


TTS Nutritionist

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