Vitamin B3 (niacin) plays a vital role in converting food into energy, supporting skin health, and maintaining the nervous system. This blood test measures the level of niacin in your blood, helping to identify potential deficiencies and support overall health.




Vitamin B3 (Niacin) Blood Test
- Results estimated in 8 working days
- Convenient testing options
- Bespoke doctor’s report
- Free delivery
Measures vitamin B3 (niacin), a key nutrient for metabolism, nervous system function, and maintaining healthy skin.
How do you want to take your sample?
Please choose one option below-
Book a venous draw at a clinic Venous+£35Visit one of our national clinic partners for a nurse to take your venous blood sample from a vein in your arm. We’ll email you instructions on how to book after we’ve processed your order.
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Book a venous draw at home with a nurse Venous+£59Book a home nurse appointment for a nurse to take your venous blood sample from a vein in your arm.
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Self-arrange a professional sample collection VenousFreeMake an appointment at a phlebotomy clinic to have your venous blood sample taken. You will be responsible for arranging your appointment and any additional fees.
18+ Only. T&Cs apply.
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Go beyond the numbers
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How it works
You have the flexibility to choose what works best for you. Enjoy the comfort of having a friendly nurse visit your home for a quick blood draw, opt for a convenient visit to one of our nationwide partner clinics, or self-arrange a draw at a location that suits you.
Take control of your health with Medichecks – order your blood test today!

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MyMedichecks is your personal online dashboard where you can view your results, access clear and simple explanations about individual health markers, monitor changes in your health, and securely store information about your medical history, lifestyle and vital statistics.
Supported by a team of specialist and qualified doctors
Dr Natasha Fernando
Medical DirectorDr Tina Ghela
Digital Clinician LeadDr Susanna Hayter
Digital Clinician
What's in the test?
Vitamins
Vitamin B3
Learn more
How to prepare for your test
Prepare for your Vitamin B3 (Niacin) Blood Test by following these instructions. Do not eat or drink anything other than water for 12 hours prior to your test. If you take medication then you are allowed to take it as you would normally. Take your sample at least 24 hours after any vitamin or mineral supplements.
Test limitations
Reviews
FAQs
What is vitamin B3?
Vitamin B3 is in foods such as eggs, peanuts, fresh fruit and vegetables, red meat, and fortified cereals.
What are the symptoms of vitamin B3 deficiency?
Although extremely rare, vitamin B3 deficiency can occur. Symptoms include fatigue, vomiting, disorientation, memory loss, and mouth swelling. Strict vegetarians and vegans may be at risk of vitamin B3 deficiency.
How many B vitamins are there?
Altogether, there are eight B vitamins, each with its purpose and role within the body. The B vitamins are all water-soluble and crucial for cell metabolism, normal functioning of the central nervous system, and the formation of red blood cells. All the B vitamins we need should be available through our diet. The B vitamins help to convert food into fuel and metabolise fats and proteins.