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Active B12

What's B12?

Vitamin B12 is part of the B complex of vitamins alongside vitamin B9 or folate. They are essential vitamins, so the body is unable to make them itself and so instead must take them in through the diet. Vitamin B12 is required for the formation of red blood cells as well as for forming a coat around nerve cells called myelin.[1]

Which tests include this marker?

What Role/s Does It Play in The Body?

Vitamin B12 plays a key role in several physiological functions. It is needed for the maturation of red blood cells, if it is not present then this can lead to pernicious anaemia which can have neurological side effects.[2]

Vitamin B12 is also required for cell metabolism and function, so deficiency can have detrimental effects on the body’s organ systems. Deficiency can be subtle and non-specific which can make diagnosis difficult.[2]

The body can store vitamin B12 which means deficiency may occur over a prolonged period.[3] The body can store up to 5mg of vitamin B12 and as the UK government recommends a daily intake of 1.5 micrograms per day, depleting these stores can take several years.[4]

How Does Vitamin B12 Affect My Wellbeing?

Vitamin B12 can only be derived from animal sources such as meat, fish and dairy. Therefore, deficiency can be common amongst the vegan and/or vegetarian community. It can also be present in pregnant women as their requirements will increase. Older people are also susceptible possibly due to poor nutrition. Some of the symptoms of 12 deficiency include:

  • Fatigue
  • Anaemia
  • Neurological features
  • Sore tongue
  • Bone marrow suppression
  • Cardiomyopathy

Usually, folate is also analysed alongside vitamin B12 as these can both be markers for macrocytic anaemias (where red cells are larger than they should be and have a reduced oxygen carrying capacity). They can also both be used to look at nutritional status especially if malnutrition is suspected. Both B vitamins are needed for adequate red cell development, cell repair and DNA synthesis.

High levels of vitamin B12 are not usually observed but may be seen with leukaemia or liver dysfunction.

How Can I Improve My Result?

Vitamin B12 can only be acquired from the diet and so this may be the best place to start with improving and maintaining B12 levels. Supplementation may be required particularly during pregnancy.


As vitamin B12 is found in foods derived from animal sources you should incorporate these into your diet. Good sources include:

  • Liver
  • Beef
  • Clams
  • Trout
  • Salmon
  • Cheese
  • Milk
  • Yoghurt
  • Eggs
  • chicken

If you cannot eat meat, then vitamin B12 supplementation may be required to ensure you have enough in your body for it to function appropriately.[5]

If your diet is high in vitamin C this can also limit the normal absorption of vitamin B12. Therefore, you should keep your intake of vitamin C within normal parameters and perhaps consume it separately to vitamin B12 where appropriate.[1]


Exercise is believed to be key to managing stress and reducing anxiety and depression.[6] You should aim to exercise for 30-60 minutes most days of the week to feel the full benefits of exercise.

However, you should bear in mind that anaemia can seriously affect your energy levels. Therefore, you may find that your performance may be affected if you are anaemic.

Tests that include this marker

Vitamin B12 (active)

Feeling tired and weak? Check your vitamin B12 levels with our home blood test kit. A lack of active B12 can cause lethargy and fatigue and this test will give you a quick and accurate result.




Track & learn how to improve 16 of the most essential health markers with the Baseline blood work test which gives you an insight into your general health and overall wellbeing.

£59 per test

Plant-Based Diet

If you are following a vegan or plant-based diet, check your body is not lacking in vital nutrients.



Is your diet supplying you with all the micronutrients your body needs for a strong immune system? This nutrition test will identify areas for improvement, helping you to keep you body strong and healthy.


Baseline Plus


Measure & track 20 key biomarkers including those essential for a strong immune system, energy levels, strong bones and good sleep.

£79 per test

Body Fit

For those who may have taken up a new challenge or returning to fitness after a break, our Body Fit profile helps you measure the positive changes exercise is having on your body, as well as ensuring your energy markers are in the right zone and you are leaving your body enough time to recover.


Immune Health

Our immune system blood check is a home blood test kit that assesses the key biomarkers that support the functioning of your immune system and identifies areas for improvement.



With over 45 biomarkers, this health check empowers you to gain a deep understanding about your inside health.



Our most advanced health check which analyses over 50 biomarkers. For those who want a deep understanding of their health.



[1] The Open University. (2017). Nutrition: Vitamins and Minerals. The Open University.

[2] Peters, P and Schaefer, C. (2007). Vitamins, Minerals and Trace Elements. In: Drugs During Pregnancy and Lactation, 2nd ed.

[3] Institute of Medicine (US). (1998). Standing Committee on the Scientific Evaluation of Dietary Reference Intakes and its Panel on Folate, Other B Vitamins, and Choline. Dietary Reference Intakes for Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington (DC): National Academies Press (US); N, Estimation of the Period Covered by Vitamin B12 Stores.

[4] Hunt, A., Harrington, D and Robinson, S. (2014). Vitamin B12 Deficiency. BMJ: 349.

[5] National Institutes of Health. (2018). Vitamin B12. Available at:

[6] Harvard Health Publishing Harvard Medical School. (2011). Exercising to Relax. Available at:

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