Optimal Ranges
Clinical (NHS) Range
197-771 pg/mL
pg/mL
Performance-Optimised Range
500-800 pg/mL
pg/mL
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 Vitamin B12 matters for performance
B12 is a cornerstone of energy metabolism and nervous system function. Even mildly low levels can cause fatigue, brain fog, and mood disturbances that are often attributed to stress or ageing. For men who train, B12 is critical for red blood cell production — directly influencing oxygen delivery to muscles. Men over 40 often have reduced absorption due to declining stomach acid production, making supplementation increasingly important regardless of dietary intake.
Symptoms
Signs your levels may be off
Low / Deficiency
- Fatigue and weakness
- Brain fog and poor concentration
- Tingling and numbness in hands and feet
- Mood changes and depression
- Pale or yellowish skin
- Glossitis (inflamed tongue)
High / Excess
- Generally well-tolerated at high doses
- Acne (at very high supplemental doses)
- Rarely, allergic reactions
Dietary Sources
Foods that support Vitamin B12 levels
Supplementation
Evidence-based supplementation approach
Methylcobalamin or hydroxocobalamin are the preferred bioavailable forms. Typical dose: 1,000-2,000 mcg daily sublingual or oral. Sublingual delivery bypasses potential absorption issues in the gut. B12 is water-soluble and non-toxic at high doses — excess is excreted. Often paired with folate (methylfolate) for optimal methylation support.
Research
Key study
Vitamin B12 deficiency: recognition and management
Langan RC, Goodbred AJ
American Family Physician (2017)
DOI: 10.7326/0003-4819-138-7-200304010-00013Related Biomarkers
Related Guides
Test your Vitamin B12 levels
Vitamin B12 is included in the Helvy 50+ biomarker panel. Get your results in 5 days with a personalised protocol.
Order Your TestThis 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.