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Full Blood Count

Mean Corpuscular Volume (MCV)

Mean corpuscular volume measures the average size of your red blood cells, reported in femtolitres. It is a calculated index from the full blood count and is one of the most diagnostically useful single numbers in blood pathology — it instantly narrows the differential when anaemia is suspected. MCV is also one of the nine biomarkers in the Levine PhenoAge composite, where rising values track biological ageing.

Optimal Ranges

Clinical (NHS) Range

80-100 fL

fL

Performance-Optimised Range

85-92 fL

fL

The clinical range defines what is considered medically “normal” — broad enough to cover 95% of the population. The performance range reflects where research and clinical experience suggest most people feel and function at their best.

Why It Matters

Why MCV matters for performance

MCV separates the three classic anaemia categories: microcytic (small cells, usually iron deficiency or thalassaemia), normocytic (normal size, often chronic disease or blood loss), and macrocytic (large cells, usually B12, folate, alcohol, or hypothyroid). Beyond anaemia, a slowly rising MCV in the upper-normal range can be the earliest hint of B12 or folate decline, even before symptoms or frank anaemia. A stable MCV in the 85-92 fL range is the longevity-friendly sweet spot.

Symptoms

Signs your levels may be off

Low / Deficiency

  • Fatigue, especially on exertion
  • Pale skin or inner lower eyelids
  • Restless legs at night (iron pattern)
  • Brittle nails or hair shedding

High / Excess

  • Tingling or numbness in feet or hands (B12 pattern)
  • Glossitis (smooth, sore tongue)
  • Mood changes or brain fog (B12 / folate pattern)
  • Unsteady gait (advanced B12 deficiency)

Dietary Sources

Foods that support MCV levels

MCV reflects nutrient status — diet drives the underlying nutrientsB12 sources: red meat, eggs, dairy, fish (no plant sources without fortification)Folate sources: leafy greens, lentils, asparagus, citrusIron sources: red meat, liver, lentils, dark chocolate

Supplementation

Evidence-based supplementation

If MCV is rising, check B12 and folate together (always — supplementing folate alone can mask B12 deficiency). For B12, methylcobalamin 1,000 mcg daily is well absorbed; injections are reserved for confirmed deficiency or absorption issues. If MCV is falling, check ferritin and transferrin saturation — gentle iron (e.g. iron bisglycinate 25 mg every other day) outperforms aggressive dosing for actual absorption.

Research

Key study

An epigenetic biomarker of aging for lifespan and healthspan

Levine ME, Lu AT, Quach A, et al.

Aging (Albany NY) (2018)

DOI: 10.18632/aging.101414

Related Biomarkers

Vitamins & Minerals

Vitamin B12 (Cobalamin)

Optimal: 500-800 pg/mL

Vitamins & Minerals

Folate (Vitamin B9)

Optimal: 20-45 nmol/L

Inflammation

Ferritin (Iron Stores)

Optimal: 80-150 ng/mL

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MCV is included in the Helvy 50+ biomarker panel. Get your results in 5 days with a personalised protocol.

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This content is for educational purposes only and does not constitute medical advice. Your data suggests areas for optimisation, but any concerns should be discussed with a qualified healthcare professional. If your results flag values outside safe ranges, we recommend consulting your GP.