Vitamin B12 Blood Test

Active B12 is the bioavailable form of vitamin B12—meaning it is the fraction of B12 that is readily absorbed and used by the body’s cells. Unlike total B12, which includes inactive forms that the body cannot utilise, active B12 is the best marker for assessing true B12 status.

Vitamin B12 is essential for:

• Energy production – Supports metabolism and reduces fatigue.
• Red blood cell formation – Helps prevent anaemia and maintains oxygen transport.
• Nervous system health – Protects nerve cells, preventing neurological damage.
• Brain function – Supports memory, concentration, and mental clarity.
• DNA synthesis – Plays a key role in cell growth and repair.

The labs we use to analyse blood samples use a healthy range of 38-188pmol/L for active b12. Data from Forth customers shows the median active b12 level for men and women is 90 and 86 pmol/L respectively, with 88% of UK adults have a level in the healthy range.

While B12 deficiency can be linked to various health conditions, including certain cancers, it is usually caused by dietary intake or absorption issues. A blood test can help identify the cause.

Common causes include poor diet (especially in vegetarians and vegans), pernicious anaemia, digestive disorders (like Crohn’s or coeliac disease), and long-term use of certain medications.

Yes, high B12 levels can occur due to supplementation or underlying health conditions such as liver disease or kidney dysfunction. A test can help determine if further investigation is needed.

For a complete picture of your health, consider testing biomarkers that work closely with vitamin B12 in energy metabolism, nerve function, and overall well-being:

• Folate (serum) – Works with B12 to support red blood cell formation and DNA synthesis. Low folate can worsen B12 deficiency symptoms.
• Ferritin – Measures stored iron levels. Low iron, along with B12 deficiency, can contribute to fatigue and anaemia.
• Red Blood Cell (RBC) Count & Haemoglobin – Helps assess if B12 deficiency is affecting red blood cell production, leading to anaemia.
• Magnesium (serum) – Supports nerve function and energy production, working alongside B12 to maintain healthy muscles and nerves.
• Vitamin D (25 OH) – Works with B12 for energy and immune function. Deficiencies in both can contribute to fatigue and weakness.

Recovery time depends on the severity of deficiency and treatment method. Many people feel improvement within a few weeks, but full recovery can take several months.

B12 is found in animal-based foods such as meat, fish, eggs, and dairy. Fortified foods, like plant-based milks and cereals, are good options for vegetarians and vegans.

Once your sample reaches our lab, you’ll receive your results within 2 days via your secure online account.

B12 injections are typically needed for severe deficiency or if you have conditions like pernicious anaemia or malabsorption issues where oral supplements are ineffective.

Yes, all our test kits are delivered in plain, unbranded packaging to protect your privacy.

If you order before midday (Mon-Fri), your test kit will be dispatched the same day and should arrive within 1-2 working days.

We use industry-leading encryption to protect your personal information. Your results are private and only accessible through your secure account.

Yes, you can choose your collection method after adding the vitamin b12 test to your basket.

If you order your test before midday on a Monday to Friday then your kit will be dispatched the same day.

All our kits are sent out via Royal Mail Tracked24, so it should be with you within 1-2 working days.

We have strict processes in place to ensure the protection of your data. Following GDPR the company also operates under tight legal rules about the sharing of data which ensures that data is only shared if it is crucial to the delivery of our service. For example, our doctors see customer results at the time of review, however, after review, access to results is withdrawn.

Learn more about your data security.

Yes. We offer two options if you do not want to do our finger prick test. The first is a home appointment where a nurse comes to your home to take a blood sample. The second is to visit a Phlebotomy clinic near you that offers a blood sample service.

A blood sample will be taken from your vein and we will provide you with everything you need to give to the nurse to allow them to take the sample.

The nurse will give you the blood sample to return to us using the pre-paid envelope provided.

We have a team of doctors and nurses who look at all results and will comment on any results that are outside of the normal range for your age.

Yes, you can download your results from your health dashboard as a PDF to share with your GP.

Learn how to export your results.