High homocysteine

Written to our editorial standards · reviewed against published research· Updated 2 Jun 2026

A high homocysteine is associated with cardiovascular and cognitive risk and is usually driven by low B vitamins, so it is one of the most directly fixable markers with methylfolate, B12, and B6.

Homocysteine is an amino acid kept in range by folate, B12, and B6 (with TMG as a backup). When those run low, or with the common MTHFR gene variant, it builds up, and elevated levels are linked to heart disease and faster cognitive decline. Lowering it with B vitamins is straightforward and measurable.

Common causes

  • Low folate, B12, or B6
  • The MTHFR gene variant
  • Kidney impairment
  • Older age
  • Heavy coffee or alcohol intake

Associated symptoms

  • Usually none (it is silent)
  • Symptoms relate to any underlying B12 deficiency

Nutrients that can help

Methylfolate
See the guide →
Methyl-B12
See the guide →
Vitamin B6
See the guide →
TMG
See the guide →
What to do

Take a methylated B-complex (methylfolate, methyl-B12, B6), and add TMG if it stays high. Recheck after about 3 months. Address coffee and alcohol intake too.

When to see a doctor

A high homocysteine is worth discussing with a doctor, who can check B12 and folate, consider kidney function, and factor it into your overall heart-health picture.

Full marker
Homocysteine: ranges, what it measures & both directions
Read the Homocysteine guide →

Common questions

What does high homocysteine mean?
A high homocysteine is associated with cardiovascular and cognitive risk and is usually driven by low B vitamins, so it is one of the most directly fixable markers with methylfolate, B12, and B6. Homocysteine is an amino acid kept in range by folate, B12, and B6 (with TMG as a backup). When those run low, or with the common MTHFR gene variant, it builds up, and elevated levels are linked to heart disease and faster cognitive decline. Lowering it with B vitamins is straightforward and measurable.
What causes high homocysteine?
Low folate, B12, or B6; The MTHFR gene variant; Kidney impairment; Older age; Heavy coffee or alcohol intake.
How do I lower my homocysteine?
Take a methylated B-complex (methylfolate, methyl-B12, B6), and add TMG if it stays high. Recheck after about 3 months. Address coffee and alcohol intake too.
When should I see a doctor?
A high homocysteine is worth discussing with a doctor, who can check B12 and folate, consider kidney function, and factor it into your overall heart-health picture.

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Educational use only, not medical advice or diagnosis. Reference ranges vary by lab, age, sex, and medication, and a single result is read in context. Always review your results with a qualified clinician.