• Sonja

Vitamin B12

Updated: Jun 24, 2019

What is B12 and do we need it?

B12, also known as cobalamin, is a water-soluble vitamin which plays an essential role in the synthesis of DNA, detoxification, formation of red blood cells, heart and bone health and is vital for brain function and a healthy nervous system. It is absorbed in the small intestines and stored in the liver for years as the body only needs a small amount each day.

It is necessary to take vitamin B12 to prevent high homocysteine levels in the blood. Raised homocysteine levels are an increased risk factor for the development of brain damage, dementia and Alzheimer’s disease. It can also damage the lining of our arteries and causes plaque formation which may lead to heart attacks and strokes. Our bodies can detoxify homocysteine with folate, vitamin B6 and B12. A balanced vegan diet usually has enough folate and B6, but is lacking in B12 which may lead to high levels of homocysteine. To avoid this, it is recommended to supplement B12 on a regular basis. It is also a good idea to get your B12 levels, as well as homocysteine and serum folate levels, tested. B12 levels should be of at least 600ng/l in the blood stream; Homocysteine should be under 12mcmol/l. If the blood test results reveal that homocysteine levels are higher than 12mcmol/l and B12 levels are too low, you would need to increase supplement intake or change to another form of B12. In case your folate level is also too low, remember to eat leafy greens and cruciferous vegetables on a daily basis (broccoli, Brussels sprouts, kale, microgreens, collard, romaine lettuce, cauliflower, asparagus, cabbage, etc.). Retest after 3 months to see if the levels are in the normal range and your body can absorb folate, B6 and B12.

Vitamin B12 is also used as a co-enzyme which is a small molecule required to help enzymes function properly. Enzymes are essential proteins that accelerate the rate of chemical reactions in the body. Vitamin B12 is needed by two enzymes in the human body: methionine synthase and methylmalonyl-CoA synthase. If there are insufficent B12 levels for these enzymes, damage to the nervous system and low energy levels may occur:

Methionine synthase is a molecule that is responsible for the regeneration of methionine from homocysteine. Methionine is an important amino acid which produces and protects DNA and is necessary for healthy gene expression. It is also responsible for the production and preservation of the myelin sheath which wraps around and protects the nerve fibre of neurons. Damage to the myelin sheath can lead to slow or interrupted nerve impulses which may cause neurological problems.

Methylmalonyl is converted into Succinyl-CoA which plays a beneficial role in the conversion of energy for the body and is also very important in the synthesis of haemoglobin which is a protein that transports oxygen in the blood.

Where does B12 come from?

B12 is made by bacteria living in the soil and water and found in animals because they eat grass with small amounts of soil and deposit the absorbed B12 in their muscles. Before the industrial revolution, our ancestors got B12 through the vegetables they ate directly from the ground or water they drank from wells, rivers and streams.

Unfortunately, today’s vegetables are sprayed with many different types of pesticides and herbicides. Those chemicals also end up in our streams and rivers and this is why it is preferable to get our B12 in the form of a supplement. Furthermore, the chlorination and treatment of our domestic water removes the vitamin B12 which would naturally be present. That’s why it is essential that we find alternative sources of B12 through supplementation and fortified food.

How can we consume B12?

In the modern world, we live in a very sterilised environment and do not get our B12 through drinking water from streams or eating vegetables straight from the ground. We therefore have two options of taking in B12: we can either eat animal products such as meat, dairy and eggs, or supplement with B12. When we consume pork, beef, eggs and milk, we also take in cholesterol, animal protein and high amounts of fat which altogether does not contribute to our health. The easiest and healthiest way of getting this essential vitamin is supplementing it in the form of capsules, pills, sublingual tablets, drops or fortified food.

What types of B12 exist and what supplement is the best for me?

There are four different types of B12

- Cyanocobalamin

- Methylcobalamin

- Adenosylcobalamin

- Hydroxocobalamin

1. Cyanocobalamin

Cyanocobalamin is an artificial, crystalised form of B12 that is converted by the body into the active forms methylcobalamin and adenosylcobalamin. It is the most cost-effective, most stable and most researched form of B12. It contains traces of cyanide but the amount is so small that it is not believed to affect healthy individuals.

However, people with chronic kidney disease should not take cyanocobalamin as the detoxification of cyanide is not guaranteed. This may lead to nerve issues.

Smokers also should not take cyanocobalamin as they already ingest a high amount of cyanide and the body is not able to handle the detoxification process properly.

Those who have previously suffered cyanide poisoning are also not recommended to take cyanocobalamin.

There also exists a cyanide metabolism defect which results in an inability to absorb B12 from cyanocobalamin. In order to convert cyanocobalamin into methylcobalamin the enzyme Methylenetetrahydrofolate Reductase (MTHFR) is needed. However, for about 10%-15% of the population, this enzyme does not work very well leading to an inability to turn cyanocobalamin into an active form which the body can absorb. This is due to a genetic defect known as homozygous MTFHR mutation. MTFHR enzymes are needed to produce both of the active forms of B12. If you have been taking a supplement with cyanocobalamin and are B12 deficient, you can do a test to check for MTFHR mutations.

2. Methylcobalamin

If it is preferred not to ingest cyanide, it is recommended to choose Methylcobolamin. It is one of the two enzymes of vitamin B12 and believed to be the most active form.

3. Adenosylcobalamin

Adenosylcobalamin, also known as coenzyme B12, is the other of the 2 enzyme forms of vitamin B12. Even though it is the least stable and effective form, in some studies people with fatigue issues have responded better to it than other forms of B12.

4. Hydroxocobalamin

Hydroxocobalamin is an injectable form of B12 which is often used for people that have problems absorbing B12 within their intestinal tract. It is also converted into the co-enzyme forms adenosylcobalamin and methylcobalamin.

What types of B12 supplements are available?

The bioavailability of the different forms of B12 supplement (capsules, pills, drops, sublingual tablets) can vary. Drops or sublingual tablets are usually the easiest form for the body to absorb. The level of purity can also vary from one supplement to another. Generally speaking, methylcobalamin drops tend to have fewer additives but can be expensive. Cyanocobalamin supplements are more shelf-stable and affordable.

It is usually sufficient to take a 2,500mcg B12 supplement twice a week. But always remember to check your B12/homocysteine/folate levels once a year to see if you are getting adequate B12.

Another way to restore B12 is to consume fortified foods such as breakfast cereals and plant-based milk. Nutritional yeast can also contain B12 if added by the manufacturer. Remember to check the package before purchasing these products.

What are the symptoms of a B12 deficiency?

B12 is responsible for proper DNA-functioning, the nervous system, energy production and the metabolism. If you do not get the right amount of vitamin B12, the following symptoms may occur:

- Sore tongue

- Mouth ulcers

- Tingling

- Depression

- Fatigue

- Memory problems

- Neuropsychiatric disorders

- Reversible nerve damage

- Hypohomicysteinemia

- Brain fog

- Numb hands and feet

- Pernicious anemia

Are some people at higher risk of B12 deficiency?

Some groups of people have a higher risk of becoming B12 deficient. This includes:

- people with digestive disorders (crohn's disease, celiac disease, IBD/IBS, GERD etc.)

- people with underlying gut issues which leads to problems with the absorption of B12

- people over 50 years of age may have problems producing enough stomach acid which leads to a low level of intrinsic factor and thus, a decreased absorption of vitamin B12 in the small intestine

- people with pernicious anemia as it leads to a loss of parietal cells which produce intrinsic factor; if the body cannot produce enough intrinsic factor, B12 cannot be absorbed

These groups should get their B12 levels tested and might need to supplement with B12.

If there is an issue with absorbing B12 through the intestinal tract, drops or sublingual tablets may help absorbing this vitamin better as it is partly absorbed in the mouth into the bloodstream with the help of salivary intrinsic factor. Ask your doctor for further advice.


B12 is an essential vitamin which is vital for optimal health. Everybody should get their B12 levels checked to ensure that they are not deficient. The most commonly used forms of B12 supplement are methylcobalamin and cyanocobalamin. Always make sure to have adequate B12 and folate levels through diet and supplementation. If you have any concerns, always check with your doctor.

Sonja from SOS Free


Recent Posts

See All