Vitamin B12 (Cobalamin) – Sources, Benefits, Deficiency, Diseases | Loaded Health
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Vitamin B12 (Cobalamin) – Sources, Benefits, Deficiency, Diseases

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Vitamin B12 (Cobalamin) is the next & the last Vitamin in the B complex group.

As you know different vitamins are needed in the body for different functions. The broad distinguishing feature is based on solubility that is water-soluble vitamins and fat-soluble vitamins.

On Loaded Health the series of Vitamins already covered Vitamin A, Vitamin B1, Vitamin B2, Vitamin B3, Vitamin B5, Vitamin B6, Vitamin B7 & Vitamin B9. The next to be discussed is Vitamin B12 (Cobalamin).

Let’s start the discussion on Vitamin B12: its mechanism, sources, benefits, deficiency, diseases, and side effects.

What Vitamin B12 is Good For?

Vitamin B12 is good for many things within the body including:

  • Helps in promoting blood cells growth
  • Increase the strength of the nerve cells
  • Helps in the production of genetic material – DNA
  • Boost immunity and give strength.

Sources of Cobalamin

Richest sources of B12 includes:

  • Beef liver 3oz = 70.7 mcg (2944% Daily Value)
  • Clams 3oz = 17 mcg (708% DV)
  • Tuna 3oz = 9.3 mcg (385% DV)
  • Yeast ¼ cup = 8.3 – 24mcg (346% DV)
  • Salmon 3oz = 2.6 mcg (108% DV)
  • Ground beef 3oz = 2.4 mcg (100% DV)
  • Milk 1 cup = 1.3 mcg (54% DV)
  • Yogurt 6oz = 1 mcg (43% DV)
  • Breakfast cereals 1 serving = 0.6 mcg (25% DV)
  • Cheddar cheese 1.5 oz = 0.5 mcg (19% DV)
  • 1 egg = 0.5 mcg (19% DV)
  • Turkey 3oz = 0.3 mcg (14% DV)

Types of Vitamin B12

There are mainly 4 variants of Vitamin B12 as listed below:


Natural coenzyme of B12 that is found in raw food sources. 


Another natural co-enzyme like methylcobalamin is found in raw food sources. 


A synthetic form of B12 is converted into one of the 2 natural co-enzymes within the body to function. It is found in supplements and fortified foods.


A highly bioavailable form of B12 is used as a medicine to treat severe B12 deficiencies. Available in the injectable form mostly.

Functions of Cobalamin

The following are the main benefits/functions of cobalamin:

  • Aids in lowering homocysteine levels
  • May lower the risk of heart disease
  • Assists in the formation of new cells as well as the breakdown of some amino acids and fatty acids
  • Helps to protect nerve cells and promotes their regular growth
  • Assists in the formation of red blood cells
  • Supports the health of your body’s blood and nerve cells
  • Create and regulate DNA (the genetic material in all of your cells)
  • Bits of help prevent megaloblastic anemia (a blood condition that makes people tired and weak)
  • Improve mood and symptoms of depression
  • Contributes to energy production and fatty acid synthesis
  • Supports Healthy Hair, Skin, and Nails
  • Prevent major birth defects
  • Assists the human body in absorbing folic acid, allowing energy to be released

Cobalamin Dosage / B12 Recommended Daily Allowance (RDA)

Harvard Health Publishing, recommended a daily dose of vitamin B12 as follows:

An average adult man and woman requires 2.4 mcg (micrograms) per day. Cobalamin can be used in a variety of ways, so your doctor can prescribe the proper dosage for you. In-depth RDA includes:

Birth to 6 months                          0.4 mcg

Infants 7–12 months                     0.5 mcg

Children 1–3 years                        0.9 mcg

Children 4–8 years                        1.2 mcg

Children 9–13 years                      1.8 mcg

Teens 14–18 years                         2.4 mcg

Adults                                             2.4 mcg

Pregnant teens and women         2.6 mcg

Breastfeeding                                2.8 mcg

Vitamin B12 Supplements

Supplements are present in usually 2 forms hydroxocobalamin and cyanocobalamin. Other common forms are adenosylcobalamin and methylcobalamin which usually occur in natural food options. 

Supplements with varying amounts of vitamin B12 are available. Some companies sell vitamin B12 levels that are far greater than suggested, such as 500 mcg or 1,000 mcg, but your body only absorbs a small portion of it. These dosages are regarded as safe.

Available in the form of capsules, tablets, injections. Vitamin B12 can also be taken as a liquid that is dissolved under the tongue (called sublingual vitamin B12). There is no evidence that one type of supplemental vitamin B12 is superior to another.

Health and Cobalamin (B12)


According to certain studies, those who have high amounts of vitamin B12 have a higher cancer risk. However, some evidence suggests that those with low amounts of vitamin B12 have a higher risk of cancer, or that vitamin B12 levels have no effect on cancer risk. To determine whether vitamin B12 levels increase cancer risk, more research is needed.


Supplementing with vitamin B12 (together with other B vitamins) lowers homocysteine levels in the blood, a chemical associated with an elevated risk of heart attack or stroke. However, despite lowering homocysteine levels, evidence demonstrates that these vitamins do not affect the risk of cardiovascular disease or stroke.


Vitamin B12 deficiency can harm your bones, therefore it’s important to keep your levels up. A study of almost 2,500 adults found that people who were deficient in vitamin B12 had lower than normal bone mineral density. 

Reduced mineral density in the bones can cause them to become brittle and fragile over time, increasing the risk of osteoporosis. Other research has linked low vitamin B12 levels to poor bone health and osteoporosis, particularly in women.


The majority of research suggests that low vitamin B12 levels in the blood do not affect the likelihood of a cognitive decline in older persons, whether or not they have dementia or Alzheimer’s disease. To further understand the effects of vitamin B12 supplementation on cognitive performance in older persons, more clinical trials are needed.


Macular degeneration is a condition related to eye problems that primarily affect central vision. Vitamin B12 deficiency may contribute to the development of age-related macular degeneration. Supplementing with vitamin B12, a type of amino acid found in the plasma, may lower homocysteine levels, according to research. 


Vitamin B12’s involvement in cell creation necessitates proper quantities to ensure healthy hair, skin, and nails. In reality, insufficient vitamin B12 levels can cause hyperpigmentation, nail discoloration, hair changes, vitiligo (skin color loss in areas), and angular stomatitis, among other dermatologic symptoms (inflamed and cracked mouth corners). Supplementing with vitamin B12 has been found to help persons with B12 deficiency improve their dermatologic symptoms.


There is no proof that vitamin B-12 pills can increase your energy or make you a better athlete unless you have a vitamin B-12 deficiency.


Vitamin B12 supplements are frequently promoted by manufacturers as aids to energy, athletic performance, and endurance. However, in those who get adequate B12 from their diet, vitamin B12 does not provide these benefits.

Deficiency of Vitamin B12 / Cobalamin Deficiency

Following are the signs and symptoms of B12 deficiency:

  • Pale skin
  • Heart palpitations
  • Loss of appetite
  • Weight loss
  • Infertility
  • Hands and feet might become numb or tingly (a sign of nerve problems)
  • Problems with balance
  • Depression
  • Confusion
  • Dementia
  • Poor memory
  • Soreness of the mouth or tongue

Vitamin B12 insufficiency in babies manifests itself in several ways

  • Failure to thrive
  • Delays in reaching the typical developmental milestones
  • Megaloblastic anemia


  • Pernicious anemia
  • Crohn’s disease
  • Chronic pancreatitis
  • Whipple’s disease 
  • Parasitic infections
  • Terminal ileal resection
  • Gastrectomy
  • Atrophic gastritis
  • H.Pylori infection
  • Long term Antacid use
  • Long term alcohol use

Cobalamin Side Effects/Toxicity

Vitamin B-12 has a very low risk of adverse effects. It isn’t regarded as poisonous in large concentrations, and even 1000-mcg dosages aren’t considered detrimental. 

Cyanocobalamin is a supplement that comes in an injectable form and contains traces of cyanide, a dangerous chemical. As a result, several people are concerned about the prospective consequences. These traces are found in many fruits and vegetables, and they are not regarded as a severe health risk. People with kidney illness, on the other hand, should avoid using this type of supplement.

Common side effects include:

  • Headache
  • Dizziness
  • Itching and redness
  • Swelling
  • Nervousness
  • Abnormal movements
  • Decrease potassium in the blood
  • Heart failure
  • Allergic reaction

Frequently Asked Questions (FAQs)


Not usually, but if taken in a very high dose for a long time can lead to drug-induced jaundice and liver injury.


No, it tends to regulate blood pressure healthily.


B12 can’t cause anxiety but its deficiency does. If you are deficient in B12 you are more prone to mental disorders like anxiety and depression.


There is a huge list of medications that should not be taken with B12 supplement or any other multivitamin supplement as these slow down the effective absorption of B12.


No, B12 does not lead to a raised heart rate but its deficiency did lead to increased heart rate to copy up with anemia associated with low B12 levels.

The Bottom Line

Vitamin B12 is needed by the body to function adequately. Even the highest doses are usually safe. Both are available in natural and supplemental form. 

You must start taking the supplement after discussing it with your health expert to avoid side effects and always take it within its RDA.

Follow Loaded Health for more updates on the micronutrients in the upcoming and previous articles.


Rabia Mirza

WordPress developer, SEO expert, Digital marketing expert & Content Strategist.

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