NutriStack
Metformin and Methylfolate, a synergy.
Metformin can lower serum folate as well as vitamin B12, with longer treatment duration linked to lower folate levels and higher homocysteine. Combined B12 and folate depletion increases the risk of macrocytosis, neuropathy, and elevated homocysteine. Methylfolate (5-MTHF) is the active circulating form of folate and is reasonable in patients with low folate or MTHFR variants.
One pair, every claim cited. The two substances, the type, the mechanism, the recommendation, and the primary literature.
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What the row says.
Every entry follows the same shape: what is happening, the mechanism, the recommendation, and the primary literature.
At a glance
- Substances
- Metformin and Methylfolate
- Pair type
- Synergy
- Evidence (highest tier)
- Moderate
- Source citations
- 2 sources
- Stack Score effect
- +2 to your Stack Score (per scored synergy row).
- Scope
- Supplement × Prescription
- Last verified
- May 30, 2026
Synergy · Moderate evidence
Synergy
What is happening. Metformin can lower serum folate as well as vitamin B12, with longer treatment duration linked to lower folate levels and higher homocysteine. Combined B12 and folate depletion increases the risk of macrocytosis, neuropathy, and elevated homocysteine. Methylfolate (5-MTHF) is the active circulating form of folate and is reasonable in patients with low folate or MTHFR variants.
Mechanism. Metformin appears to reduce intestinal folate absorption and may alter folate transport in enterocytes, lowering serum folate over time. Methylfolate provides the bioactive form that bypasses dihydrofolate reductase and MTHFR steps, supporting methionine synthesis and homocysteine remethylation.
Recommendation. If you take metformin long-term and have low folate, macrocytic anemia, or elevated homocysteine, consider methylfolate (typically 400-1000 mcg/day) in addition to B12 supplementation. Check folate, B12, and homocysteine periodically and discuss with your prescriber.
Sources (2)
- Kanti G, Anadol-Schmitz E, Bobrov P, et al. Vitamin B12 and Folate Concentrations in Recent-onset Type 2 Diabetes and the Effect of Metformin Treatment. J Clin Endocrinol Metab. 2020;105(6):e2105-e2114. PMID 32219330
- Wale Tesega W, Genet S, Natesan G, et al. Assessment of Serum Vitamin B12 and Folate Levels and Macrocytosis in Patients with Type 2 Diabetes Mellitus on Metformin Attending Tikur Anbessa Specialized Hospital, Addis Ababa, Ethiopia: A Cross-Sectional Study. Diabetes Metab Syndr Obes. 2021;14:1967-1975. PMID 33976561
Stack Score
How this pair moves the number.
Effect on the composite score
If both Metformin and Methylfolate are in the same stack, this pair applies +2 to your Stack Score (per scored synergy row).
The full algorithm, the clamping rules, and four worked stacks are documented at /methodology/stack-score.
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