Erythrocyte Folate
Other marker
Red Cell Folate
Erythrocyte Folate
Folate concentration inside red blood cells. Reflects tissue folate status over the previous 3-4 months (the RBC lifespan), making it a more stable marker of long-term folate stores than serum folate, which mirrors recent dietary intake.
PED Notes
Most athletes do not need this test if serum folate is adequate. It becomes useful when serum folate is borderline, when macrocytic anaemia is present, or when long-term folate status needs confirmation independent of recent supplementation. Heavy training and AAS-driven erythropoiesis increase folate demand for DNA synthesis in new red cells. Methylfolate and folic acid both raise this marker, although MTHFR polymorphisms affect how efficiently folic acid is converted. Pair with B12 (cobalamin) and homocysteine for a full one-carbon metabolism picture, since isolated folate repletion can mask B12 deficiency and worsen neurological symptoms.
When high
High RBC folate is usually benign and reflects supplementation or dietary fortification.
When to investigate:
- Unsupplemented value persistently above the upper reference range can indicate intracellular sequestration (rare) or laboratory variation
- Very high folate combined with low or borderline B12 may mask the haematological signs of B12 deficiency while neurological damage progresses
Action:
- Confirm B12 (serum cobalamin, or holotranscobalamin if available) and homocysteine
- If using folic acid supplements at high doses (>1mg/day), consider switching to methylfolate or stopping supplementation and rechecking in 12 weeks
When low
Supplements:
- Methylfolate (5-MTHF) -- 800-1000mcg/day (active form, bypasses MTHFR gene variants; safer than folic acid in B12-deficient individuals because it does not mask haematological signs of B12 deficiency)
- Folic acid -- 400-800mcg/day (cheaper alternative; only use if B12 status is confirmed adequate)
- Always recheck Vitamin B12 before supplementing folate aggressively; correcting folate without B12 can precipitate or worsen subacute combined degeneration of the spinal cord
Dietary sources:
- Leafy greens (spinach, kale), legumes, asparagus, citrus, fortified grains, liver
Lifestyle:
- Reduce alcohol (impairs folate absorption and accelerates folate breakdown)
- Review medications (methotrexate, sulfasalazine, phenytoin, trimethoprim deplete folate)
- Recheck at 8-12 weeks; RBC folate responds slowly because it reflects 3-4 months of red cell turnover
History Chart
Reading History
Frequently Asked Questions
Reference Ranges
Standard Range
VitalMetrics Range