Vitamin B12 and folate (vitamin B9) are essential cofactors in DNA synthesis and play a crucial role in the production of red blood cells. They work together in several key processes:
• DNA synthesis
• Methylation cycle: regulates gene expression, detoxification, and cellular repair
• Neurological health: supports the brain and nervous system, including cognition, mood, and movement
• Homocysteine regulation: helps protect the heart, brain, and blood vessels
Key roles of folate and vitamin B12
1. DNA synthesis and cell division
Both are required for DNA production and normal cell division. Deficiency may lead to abnormally large red blood cells (megaloblastic anaemia, with raised MCV).
2. Nervous system
Vitamin B12 is essential for maintaining the myelin sheath, which speeds up nerve signal transmission. Deficiency may cause:
- Numbness in the hands and feet
- Memory decline
- Long-term risk of irreversible neuropathy
3. Methylation cycle
Folate and B12 are required to convert homocysteine into methionine. Deficiency may lead to elevated homocysteine levels, increasing the risk of vascular damage.
Typical reference ranges
- Vitamin B12 (pg/mL)
• < 200: Deficiency
• 200–300: Borderline
• 400–900: Functionally optimal
• ~1,000: Consider investigating cause of elevated levels
(In functional medicine, a target of > 500 is often preferred.)
Serum folate (ng/mL)
• < 4: Deficiency
• 4–7: Borderline
• 8–20: Adequate
(In functional medicine, a target of > 15 is often recommended.)
What do low levels indicate?
- Poor nutrition
- Alcohol consumption
If both B12 and folate are low:
- Anaemia with elevated homocysteine
- Low B12 with high MCV
- Megaloblastic anaemia
Importance for longevity
- Epigenetic stability
B12 and folate help maintain methyl donor balance, influencing DNA methylation patterns that regulate gene expression and biological ageing. - Cardiovascular risk reduction
- Regulate homocysteine levels
- Reduce endothelial dysfunction
- Cognitive protection
Low levels are associated with cognitive decline and impaired memory.
Recommended laboratory tests
To assess status more comprehensively, consider:
- Homocysteine
- MCV
- Ferritin
- hs-CRP
- MMA (methylmalonic acid): ช่วยยืนยัน B12 deficiency
Note: Vitamin B12 may appear “normal” in blood tests, yet a functional deficiency can still be present.
Summary
Folate and vitamin B12 always work together and act as core regulators of DNA synthesis, methylation cycle, and neurovascular integrity.
Dr.Apakorn Poltian
