Everything you need to know about vitamin B12

Vitamin B12 is an important vitamin that plays a vital role in many functions in your body. Including but not limited to red blood cell production, DNA synthesis and supporting nerve cell function. Discover exactly what it is and how it benefits your body. We also guide you on the best way to optimise your Vitamin B12 intake.

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What is Vitamin B12?

Vitamin B12 refers to a family of cobalamin compounds containing the porphyrin-like, cobalt-centered corrin nucleus. Of the several cobalamin compounds that exhibit vitamin B12 activity, cyanocobalamin and hydroxocobalamin are the most active. It is a water-soluble vitamin, which means that it dissolves in water and is carried through to the body’s tissues but it is not stored in the body itself.  

Vitamin B12 plays various roles in your body, including supporting nerve cell function, red blood cell production and DNA synthesis. Find out what it is, how it benefits your health and which foods are the best sources of vitamin B12.

What does Vitamin B12 do for our bodies?

Vitamin B12 has many functions. It's necessary for normal metabolism of cells in the GI tract and bone marrow. 

Vitamin B-12 is crucial to the normal function of the brain and the nervous system. It is also involved in the formation of red blood cells and helps to create and regulate DNA. Vitamin B12 is an important macronutrient for healthy nutrition. In fact, it plays a vital role in cell production, making it an incredibly important vitamin for maintaining healthy hair, skin and nails in addition to the assistance vitamin B12 gives the nervous system.

Vitamin B12 has been known to assist in boosting energy levels

Fatigue is often one of the first signs of a vitamin B12 deficiency. If you suffer from a vitamin B12 deficiency, increasing your vitamin B12 intake will replace the missing nutrients. Vitamin B12 can be found naturally in supplementing vitamin B12 can help boost your energy levels. All of the B vitamins play a role in your body’s production of energy. However there is no scientific evidence to suggest that taking a vitamin B12 supplement will help boost your energy levels if you already have sufficient vitamin B12 levels.

Vitamin B12 helps to reduce the loss of brain neurons

Sufficient vitamin B12 can help reduce the loss of brain neurons (brain atrophy) which commonly occurs in elderly adults. A study on people with below average vitamin B12 levels, found that supplementing vitamin B12 improved their memory even without being diagnosed with a deficiency.

Vitamin B12 can help to improve your mood

Vitamin B12 helps synthesize and metabolize serotonin. Serotonin is a neurotransmitter that helps promote feelings of happiness and wellbeing. Low serotonin levels are linked to depression and irritability. A vitamin B12 deficiency can cause a decrease in your serotonin production, so supplementing vitamin B12 is a great way to help boost your mood.

Vitamin B12 supports bone health

Vitamin B12 is crucial for the development and promotion of healthy bones. When you have a vitamin B12 deficiency it is linked to lower bone mineral density, which leads to conditions like osteoporosis - especially in older women.

Vitamin B12 helps to prevent anemia

Vitamin B12 is vital for red blood cell production (your red blood cells are responsible for transporting oxygen to your organs). Low levels of vitamin B12 can cause reduced numbers of red blood cells, causing megaloblastic anemia which is when your bone marrow produces unusually large and structurally abnormal, immature red blood cells, this means your body isn’t getting enough oxygen.

When your body isn’t getting sufficient oxygen, you could experience symptoms like weakness and fatigue.

Vitamin B12 supports and promotes eye health

Vitamin B12 can help maintain and promote healthy eyesight. As we get older, many of us suffer from macular degeneration (loss of eyesight).

In a study on 5 000 women over the age of 40, sufficient vitamin B12 intake was linked to 34-41% lowered risk of macular degeneration.


Why is Vitamin B12 important to my Body?

The Symptoms of a vitamin B12 deficiency

Pernicious anemia is a vitamin B12 deficiency caused by atrophic gastritis, chronic inflammation of the stomach mucus membrane, and a lack of intrinsic factor, which is the glycoprotein that is secreted by the stomach, the intrinsic factor is  necessary for the absorption of cyanocobalamin (vitamin B 12) in the intestine

Anemia of folate deficiency - This form of anemia is characterised by large, immature red blood cells, which indicate slow DNA synthesis and an inability to divide.

Food cobalamin malabsorption - Results in a lemon-yellow tint to the skin and eyes; a smooth beefy tongue and neurologic disorders.

Marginal vitamin B12 deficiency impairs intelligence, spatial ability and short-term memory. Advanced neurological symptoms include a creeping paralysis that begins at the extremities, such as hands and feet, and then works inward and up along the spine.

Progressive neuropathy causes numbness, tingling and burning of the feet, stiffness and generalised weakness of the legs.

Causes of vitamin B12 deficiency

Most vitamin B12 deficiencies reflect inadequate absorption, not poor intake. Inadequate absorption typically occurs for one of two reasons: a lack of hydrochloric acid or a lack of intrinsic factor. Without hydrochloric acid, the vitamin is not released from the dietary proteins and so is not available for binding with the intrinsic factor. Without the intrinsic factor, the vitamin cannot be absorbed.

Many people, especially those over 50, develop atrophic gastritis, a common condition in older people that damages the cells of the stomach. Atrophic gastritis is when the stomach mucus membrane becomes inflamed which leads to a loss of important cells. 

Atrophic gastritis may also develop in response to iron deficiency or infection with helicobacter pylori, the bacteria implicated in ulcer formation. Without healthy stomach cells, production of hydrochloric acid and intrinsic factor diminishes.

Vegan diets may also create a vitamin B12 deficiency. People who stop eating animal-derived foods containing Vitamin B12 may take several years to develop deficiency symptoms because the body recycles much of its Vitamin B12, reabsorbing it over and over again. Even if the body fails to absorb Vitamin B12, a deficiency may take up to three years to develop because the body conserves its supply.

The Symptoms for a Vitamin B12 overdose

There are currently no known toxic levels of Vitamin B12. No adverse effects have been reported for excess vitamin B12 and no upper level has been set.

What are the best sources of Vitamin B12?

Natural food sources of vitamin B12

Vitamin B12 is naturally found in meat, poultry, fish, eggs, milk  and milk products.

Yeast, sea algae and fermented soy products such as miso, do not contain the active form of Vitamin B12. 



Vitamin B12 (ug)

Beef liver






Cottage cheese

1 cup



1 cup


Skim milk

1 cup



1 egg


Supplementation of vitamin B12

Yes, you can supplement Vitamin B12. In dietary supplements, vitamin B12 is usually present as cyanocobalamin. Which is a form that the body readily converts to the active forms methylcobalamin and 5-deoxyadenosylcobalamin. Dietary supplements can also contain methylcobalamin and other forms of vitamin B12.

Existing evidence does not suggest any differences among the various sources of vitamin B12 with respect to absorption or bioavailability. However the body’s ability to absorb vitamin B12 from dietary supplements is largely limited by the capacity of intrinsic factor.  For example, only about 10 mcg of a 500 mcg oral supplement is actually absorbed in healthy people.


Vitamin B12 recommendations

The RDA for vitamin B12 in adults is 2.4 micrograms a day. 

Nutrigenetics (MTHFR Gene)

MTHFR is an enzyme, the primary function of which is to convert homocysteine to methionine.

The methylated form of folate, N5 methyltetrahydrofolate, is required for the remethylation of homocysteine to methionine. By inhibiting this remethylation pathway, folate deficiency induces homocysteine efflux into the circulation. One major metabolic role for vitamin B12 is the synthesis of methionine from homocysteine.

Folate and vitamin B12 deficiencies also cause hyperhomocysteinemia, which is a risk factor for atherosclerosis. Homocysteine is increased in the plasma of patients with deficiency of vitamin B12 or folate.

Increased homocysteine concentrations also are associated with increased risk for cardiovascular disease. The Physicians Heart Study showed that homocysteine concentrations 12% above reference values conveyed a threefold increase in the risk of myocardial infarction.

Hyperhomocysteinemia also has been reported to increase the risk for venous thrombosis. The National Health and Nutrition Examination Survey (NHANES III) showed that participants in the highest quartile of homocysteine concentrations had an increased risk for stroke.

Heterozygous (CT allele) and homozygous (TT allele) individuals need to increase their intake of both folate and Vitamin B12 to prevent having elevated homocysteine levels.


How can DNAFit assist you and your Vitamin B12 requirements?

If you have any queries or questions regarding your vitamin B12 levels, DNAFit is able to assist.

Snapshot by DNAFit

Snapshot is an at home blood test which tests, among other markers, vitamin B12 to determine current levels. Simply put, Snapshot adds an additional layer of insight into our bodies by tracking five key health categories we are able to check your internal health categories:

  1. Fats and cholesterol
  2. Vitamins
  3. Liver function
  4. Iron
  5. Inflammation

Amplify By DNAFit

By utilising genetic information from your DNAFit reports we are able to formulate the perfect supplement for you. DNA looks at your needs and is able to ensure that you receive all your nutritional needs from three capsules or less. With Amplify from DNAFIt you are finally able to say goodbye to trial and error.

Amplify would be able to provide 120ug (5000% RDA) for individuals with a normal vitamin B12 requirement and 250ug (10000% RDA) for individuals with a raised need, essentially those with a vitamin B12 deficiency.

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