Single-biomarker blood testVitamin B3 (Niacin) Blood Test
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Vitamin B3 (Niacin) Blood Test

£99 ✓ In Stock

What's covered in the price: Laboratory-supplied test kit with sample collection materials and prepaid return packaging. Results turnaround varies by test — see the estimated turnaround time shown above.
Results ready within 8 working days

Your sample goes to a UKAS accredited laboratory meeting ISO 15189 standards.

Date of birth required

After you receive your order confirmation email, please reply with your date of birth.

Blood sample
Clinic visit
(phlebotomy charges apply)
CQC registered Accredited UK labs ISO 15189

How it works

Your testing journey

From order to results in four simple steps. Full transparency on where each step happens and what it costs.

1
Medi Test Direct kit delivered by post

Receive your kit by post

Dispatched same working day if ordered before 3pm. Royal Mail Tracked delivery, typically 1–3 working days. 90% of kits arrive within 24 hours.

2
Clinic sample collection

Visit a partner clinic

Book a phlebotomy appointment at one of our 365+ UK partner clinics. Take your kit with you — the phlebotomist will collect your sample using the materials provided.

Phlebotomy fee applies (paid at clinic)
3
Venous blood draw at a clinic

Venous blood draw at a clinic

A trained phlebotomist takes a small blood sample from a vein in your arm using the vacutainers provided in your kit. The appointment takes around 10 minutes.

4
Return sample by prepaid envelope

Return by prepaid envelope

Seal your sample in the biohazard bag provided and drop it in any Royal Mail postbox using the prepaid Tracked 24 envelope. Post Monday–Thursday for best results.

Vitamin B3 (niacin) is a water-soluble B vitamin that plays a vital role in converting food into cellular energy, supporting over 400 enzymatic reactions in your body. It is essential for maintaining healthy skin, supporting nervous system function, and promoting cardiovascular health. Niacin also contributes to DNA repair and the production of stress and sex hormones in the adrenal glands.

This test is particularly valuable if you experience persistent fatigue, skin problems such as dermatitis or rough scaly skin, digestive issues, mental fog or confusion, or have dietary restrictions that may limit niacin intake. Individuals with alcohol dependence, those with malabsorption conditions, people taking certain medications (like isoniazid for tuberculosis), or those with carcinoid syndrome may be at increased risk of deficiency. Severe niacin deficiency causes pellagra—characterised by the "4 Ds": dermatitis, diarrhoea, dementia, and if untreated, death.

What's covered in the price: You receive a venous blood collection kit and professional laboratory analysis. Because this test requires a venous blood draw, you'll need to arrange collection with a qualified phlebotomist—either at a clinic near you or through your own arrangements. A phlebotomy fee may apply separately. Your results will be ready within 8 working days.

Venous Blood Collection Kit

This kit is sent to you and taken to your chosen clinic. The phlebotomist will collect your sample using the materials provided.

  1. 1Vacutainer blood collection tubes
  2. 2Needle and butterfly needle
  3. 3Tourniquet
  4. 4Alcohol swab
  5. 5Cotton wool and gauze
  6. 6Adhesive plaster
  7. 7Biohazard specimen bag
  8. 8Prepaid return envelope (Royal Mail Tracked 24)
  9. 9Laboratory request form
  10. 10Instructions for the phlebotomist
Fasting: Do not eat or drink anything other than water for 12 hours prior to your test. If you take medication, you are allowed to take it as you would normally. Supplements: Stop taking any B-vitamin or multivitamin supplements for at least 24 hours before your blood draw to ensure accurate baseline measurements. Alcohol: Avoid alcohol for 24 hours before the test.

Vitamin B3 (niacin) is a water-soluble B vitamin crucial for cellular metabolism, converting food into energy, normal functioning of the central nervous system, and the formation of red blood cells. It exists in two forms—nicotinic acid and nicotinamide—both of which contribute to the production of NAD and NADP, coenzymes involved in over 400 biochemical reactions. Niacin supports healthy skin, digestive function, and mental health. It also plays a role in cholesterol metabolism. Deficiency can cause fatigue, headaches, skin problems, digestive issues, and in severe cases, pellagra with its characteristic symptoms of dermatitis, diarrhoea, and dementia. Good dietary sources include eggs, peanuts, fresh fruit and vegetables, red meat, fish, poultry, and fortified cereals. The body can also synthesise niacin from the amino acid tryptophan. Results outside the normal range may need a follow-up with your GP.

Medical Disclaimer

This test is for screening and information only — it is not a medical diagnosis or professional advice. Please have your results reviewed by a qualified doctor or healthcare provider who can explain what they mean for your personal health situation. If your results show anything outside the normal range, or if you're worried about your health, see your doctor as soon as you can. Don't change any medications or treatments based on these results alone — always talk to your healthcare provider first.

NO CLINICS, NO QUEUES, NO HASSLE

Four steps to clarity

Pick your panel 01

Pick your panel

Browse over 200 clinically designed test kits and choose the one that fits your goals.

Kit to your door 02

Kit to your door

Everything you need arrives in discreet packaging with step-by-step instructions inside.

Collect your sample 03

Collect your sample

Follow the simple instructions in your kit — whether it's a finger-prick at home or a venous draw at a partner clinic.

Insights delivered 04

Insights delivered

Clear, easy-to-understand results sent to you online with actionable health guidance.

Frequently asked questions

No. Vitamin levels are not significantly affected by recent food intake.

Niacin is essential for energy metabolism. Severe deficiency causes pellagra (diarrhoea, dermatitis, dementia). Mild deficiency is more common and can cause fatigue, poor concentration, and skin problems. Niacin is also used therapeutically for cholesterol management.

High-dose niacin supplements can cause flushing (warmth, redness, itching), liver effects, and glucose changes. Testing helps determine whether supplementation is appropriate and at what level.

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