L-5-Methyltetrahydrofolate Calcium Encyclopedia — Scientific Background

What Is L-5-Methyltetrahydrofolate Calcium?

L-5-Methyltetrahydrofolate calcium (CAS 151533-22-1), also known as levomefolate calcium, calcium L-5-methyltetrahydrofolate, or L-5-MTHF-Ca, is the calcium salt of L-5-methyltetrahydrofolic acid (L-5-MTHF), which is the predominant naturally occurring folate in foods. It is chemically characterized by the molecular formula C₂₀H₂₃CaN₇O₆·xH₂O (anhydrous formula weight 497.52) and has a specified 1:1 ratio of L-5-methyltetrahydrofolate (L-5-MTHF) and Ca²⁺. The compound occurs as a white to light yellowish, almost odorless, crystalline powder.

The Active Folate Advantage

L-5-MTHF is the predominant naturally circulating form of folate in plasma and the primary biologically active form of folate in the human body. Unlike synthetic folic acid, which requires multiple enzymatic reduction steps—including conversion by methylenetetrahydrofolate reductase (MTHFR)—to become bioactive, L-5-MTHF is directly usable by all tissues without enzymatic conversion.

This direct bioavailability offers several potential advantages over folic acid:

• No MTHFR Dependency — L-5-MTHF bypasses the MTHFR enzyme, which is subject to common genetic polymorphisms (including C677T and A1298C) that reduce enzyme activity in a significant portion of the population.

• Direct Cellular Utilization — L-5-MTHF is the primary methyl donor for the remethylation of homocysteine to methionine, a reaction catalyzed by methionine synthase.

• Superior Bioavailability — Studies consistently demonstrate that levomefolate calcium is at least as, and in some cases more, bioavailable than folic acid.

Physiological Functions of L-5-MTHF

L-5-MTHF is critical for numerous physiological functions:

• DNA Synthesis and Repair — L-5-MTHF is a coenzyme for thymidylate synthase and purine synthesis, essential for DNA replication and repair.

• Red Blood Cell Production — L-5-MTHF participates in hemoglobin synthesis and the maturation and division of red blood cells.

• Homocysteine Regulation — L-5-MTHF is a cofactor for methionine synthase, which converts homocysteine to methionine, supporting healthy homocysteine metabolism.

• Neural Tube Development — L-5-MTHF is critical for fetal development, supporting neural tube formation and spine integrity.

• Neurotransmitter Synthesis — L-5-MTHF participates in the synthesis of neurotransmitters including serotonin, dopamine, and norepinephrine.

• Amino Acid Metabolism — L-5-MTHF is involved in the metabolism of several amino acids, including serine, glycine, and histidine.

Mechanisms of Action

One-Carbon Metabolism and Methylation Cycle

L-5-MTHF is the primary methyl donor in the one-carbon metabolism pathway. It donates its methyl group to homocysteine in a reaction catalyzed by methionine synthase (which requires vitamin B12 as a cofactor), producing methionine and tetrahydrofolate (THF). Methionine is then converted to S-adenosylmethionine (SAMe), the universal methyl donor for numerous biological methylation reactions, including DNA methylation, neurotransmitter synthesis, and phospholipid metabolism.

Homocysteine Regulation

L-5-MTHF is a cofactor for methionine synthase, which catalyzes the remethylation of homocysteine to methionine. This reaction is a major route for homocysteine disposal, and adequate L-5-MTHF levels help maintain healthy homocysteine concentrations, supporting cardiovascular health.

MTHFR Polymorphism Bypass

The MTHFR enzyme catalyzes the conversion of 5,10-methylenetetrahydrofolate to 5-methyltetrahydrofolate, the rate-limiting step in the folate cycle. Common MTHFR polymorphisms (C677T and A1298C) reduce enzyme activity, limiting the conversion of folic acid to L-5-MTHF. Supplementation with L-5-MTHF bypasses this metabolic bottleneck, providing the directly usable active form of folate.

The Stability Challenge

Despite its essential physiological functions, native L-5-MTHF-Ca presents significant formulation and stability challenges. The compound is sensitive to light, pH variations, oxidative stress, thermal degradation, and fermentation conditions, which can compromise its stability during storage and digestive transit.

These stability challenges have driven the development of advanced delivery systems, including liposomal encapsulation. Multilayer liposome-loaded 5-MTHF exhibited better physical stability and >80% 5-MTHF retention under various conditions, including salt and pH variations, as well as oxidative, thermal, fermentation, and UV stress. During in vitro digestion, the liposomal formulation enhanced the delivery of 5-MTHF to the small intestine, highlighting its application prospects as a stable, highly digestible folate supplement.

Liposomal L-5-MTHF Calcium

Liposomal encapsulation of L-5-MTHF-Ca provides a fundamentally different delivery mechanism from conventional forms. The phospholipid bilayer surrounds the L-5-MTHF molecule, forming a protective shell that enhances stability, bioavailability, and cellular uptake. This delivery system:

• Achieves >80% 5-MTHF retention under salt, pH, oxidative, thermal, fermentation, and UV stress conditions

• Enhances delivery of 5-MTHF to the small intestine

• Protects L-5-MTHF from gastric degradation and first-pass metabolism

• Provides the directly active folate form without requiring MTHFR-dependent conversion

• Disperses in water to re-form a liposomal suspension

Clinical Evidence

Homocysteine Regulation — Clinical Studies

L-5-MTHF is a cofactor for methionine synthase, which converts homocysteine to methionine. Clinical studies have demonstrated that L-5-MTHF supplementation supports healthy homocysteine metabolism, particularly in individuals with MTHFR polymorphisms who have reduced capacity to convert folic acid to its active form.

MTHFR Polymorphisms — Clinical Relevance

The MTHFR C677T polymorphism is present in approximately 10% of the population in homozygous form and 40% in heterozygous form, resulting in reduced enzyme activity and impaired conversion of folic acid to L-5-MTHF. Supplementation with L-5-MTHF provides a directly usable form of folate for these individuals, bypassing the metabolic bottleneck.

Prenatal Health — Clinical Guidelines

Adequate folate intake before and during early pregnancy significantly reduces the risk of neural tube defects such as spina bifida and anencephaly. Clinical guidelines recommend that women who are planning pregnancy or could become pregnant should take 400–800 mcg of folate per day before becoming pregnant.

Safety and Regulatory

L-5-MTHF-Ca has a well-established safety profile. The Tolerable Upper Intake Level (UL) for folic acid from supplements is 1,000 mcg/day for adults. High-dose folate supplementation may mask vitamin B12 deficiency.

Regulatory Status:

• United States — L-5-MTHF-Ca is regulated as a dietary supplement ingredient and food additive. It is Generally Recognized As Safe (GRAS) for use in food and dietary supplements. It is monographed in the USP with a reference standard available (Catalog No. 1379081 for Calcium D,L-5-Methyltetrahydrofolate).

• European Union — L-5-MTHF-Ca is authorized as a vitamin and mineral substance which may be used in the manufacture of food supplements. It is monographed in the European Pharmacopoeia.

• Global Standards — L-5-MTHF-Ca is monographed in the USP, European Pharmacopoeia, and Food Chemicals Codex (FCC). The product is available with Halal and Kosher certifications.

Precautions: L-5-MTHF-Ca is generally well tolerated at recommended doses. High-dose folate supplementation may mask vitamin B12 deficiency. Individuals with known vitamin B12 deficiency should consult a healthcare professional before use. L-5-MTHF-Ca may interact with certain medications, including methotrexate, phenytoin, and sulfasalazine. Pregnant or lactating women and children should consult a healthcare professional before use.

Testing protocols must adhere to international standards including USP, European Pharmacopoeia, and FAO/WHO Codex Alimentarius. Formulators should verify local regulatory requirements prior to market entry.

This product is intended for research, nutraceutical, and functional food applications. Not intended to diagnose, treat, cure, or prevent any disease.

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