5-MTHF Folate – Benefits and Methylated Form

Folic Acid – What It Is and Why It Is Important for the Body

Folic acid, also known as vitamin B9, is a chemical compound essential for the proper functioning of the human body. Its active form, most easily absorbed by the body, is 5-MTHF (methylfolate). Folic acid belongs to the water-soluble vitamins and plays a key role in many metabolic processes.

In the body, vitamin B9 is involved in the synthesis of nucleic acids (DNA and RNA), making it essential for cell division and growth. Therefore, adequate intake is particularly important during periods of rapid development – in childhood, adolescence, and during pregnancy. Because of its role in reproductive processes and fetal development, folic acid is one of the most commonly recommended vitamins for women planning pregnancy or who are pregnant.

Folic acid also plays an important role in amino acid metabolism, including homocysteine. Maintaining its proper level reduces the risk of cardiovascular diseases such as atherosclerosis or heart attack. Furthermore, vitamin B9 supports the nervous system and neurotransmitter production, and it is involved in the formation of red blood cells, protecting against megaloblastic anemia.

Methylated Folic Acid (5-MTHF) – How It Differs from Regular Folic Acid

An increasing number of supplements on the market contain the active form of vitamin B9 — 5-MTHF (5-methyltetrahydrofolate). Unlike synthetic folic acid, 5-MTHF is already in a biologically active form and can be immediately used in metabolic reactions without the need for enzymatic conversion.

Standard synthetic folic acid must be converted into its active form; in some individuals (carriers of MTHFR gene variants) this conversion is limited. In such cases, supplementation with ready-to-use 5-MTHF provides a more predictable metabolic and clinical effect.

Advantages of 5-MTHF: bioavailability without enzymatic conversion, lower risk of accumulation of unmetabolized folic acid, beneficial effect in individuals with impaired conversion (e.g., MTHFR variants). For this reason, 5-MTHF is often recommended for women planning pregnancy, individuals with confirmed MTHFR mutations, and patients with absorption disorders.

However, it should be emphasized that the literature is not entirely consistent — some pharmacokinetic studies show the superiority of 5-MTHF bioavailability, while in some clinical studies the effect (e.g., homocysteine reduction) at standard doses is comparable between forms. Therefore, the choice of supplement form should depend on the individual situation of the patient and consultation with a doctor or dietitian.

Sources: Willems F. et al. (2004) — pharmacokinetic study; Venn A. et al. (2003); Lamers Y. et al. (2004); systematic reviews on 5-MTHF and folic acid conversion.

What Does Folic Acid Do? Key Functions in the Body

Folic acid performs a range of important functions in the body, making it essential for health and proper development. Supplementation with vitamin B9 is recommended at various stages of life, and adequate intake supports many physiological processes.

1. Proper Fetal Development

One of the most important roles of folic acid is its involvement in neural tube closure in the developing fetus. A deficiency of this vitamin in the early weeks of pregnancy increases the risk of neural tube defects (e.g., spina bifida). Therefore, folic acid is routinely recommended for women who are pregnant or planning conception.

2. Red Blood Cell Production

Folic acid participates in the production of erythrocytes. Its deficiency can lead to megaloblastic anemia, characterized by weakness, fatigue, and concentration problems. Together with vitamin B12, it plays a key role in the formation of healthy, functional red blood cells.

3. Homocysteine Metabolism

Folic acid, along with vitamins B6 and B12, participates in the metabolism of homocysteine — an amino acid whose excess in the body is associated with an increased risk of atherosclerosis, heart disease, and stroke. Adequate folic acid levels help maintain homocysteine within normal limits, thereby supporting cardiovascular health.

4. Nervous System Support

Vitamin B9 is involved in the synthesis of neurotransmitters such as serotonin and dopamine. This affects mood, memory, and cognitive abilities. Therefore, maintaining appropriate levels may support mental balance and reduce the risk of mood disorders.

5. DNA Synthesis and Cell Division

As a key element in nucleic acid synthesis, folic acid supports cell growth and regeneration. This is important not only during prenatal development but also in tissue healing, regeneration, and periods of intense physical activity.

Sources: World Health Organization (WHO) – recommendations for folic acid supplementation during pregnancy; National Institutes of Health (NIH) – Folate Fact Sheet; reviews on homocysteine and cardiovascular diseases.

Folic Acid During Pregnancy – Why It Is So Important

Folic acid during pregnancy is one of the most important vitamins recommended for women planning motherhood or who are pregnant. Adequate intake already at the stage of conception planning and in the early weeks of pregnancy is crucial for proper fetal development.

Prevention of Neural Tube Defects

The most important role of folic acid during the prenatal period is participation in neural tube closure, from which the baby's brain and spinal cord develop. Vitamin B9 deficiency increases the risk of severe congenital defects such as spina bifida or anencephaly. Therefore, supplementation should be started at least one month before planned pregnancy.

Impact on Nervous System and Brain Development

Folic acid supports DNA synthesis and cell division, which is particularly important during the intensive development of fetal nerve cells. Adequate maternal folate levels may reduce the risk of cognitive development problems in the child.

Support for the Blood System

Vitamin B9 is essential for the proper formation of red blood cells. Supplementation during pregnancy helps prevent megaloblastic anemia, which may increase the risk of perinatal complications and negatively affect the child's development.

Recommended Supplement Dosages

According to GIS guidelines, the maximum amount of folic acid in the recommended daily dose of a dietary supplement is:

• 600 µg – in supplements for adults
• 800 µg – in supplements dedicated to pregnant women

Supplementation should be tailored to individual needs and recommendations of a doctor or dietitian. In cases of MTHFR gene mutations or other risk factors, a healthcare professional may recommend the active form of folic acid (5-MTHF).

Folic Acid Deficiency – Symptoms and Health Consequences

Folic acid deficiency can lead to serious health consequences in both adults and pregnant women. Vitamin B9 plays a key role in DNA production, cell division, and red blood cell formation, so its lack results in multiple physiological disturbances.

Symptoms of Folic Acid Deficiency

• Fatigue, weakness, lack of energy
• Headaches, difficulty concentrating
• Pale skin and mucous membranes
• Digestive problems – nausea, loss of appetite
• Megaloblastic anemia – enlarged and abnormal red blood cells
• In pregnant women – increased risk of neural tube defects in the fetus

Health Consequences

Folic acid deficiency can affect the nervous, cardiovascular, and hematological systems. In adults, it increases the risk of elevated homocysteine levels, a risk factor for heart disease and stroke. In pregnant women, deficiency increases the risk of miscarriage, preterm birth, and developmental defects in the child.

Sources: National Institutes of Health (NIH) – Folate Fact Sheet; WHO – "Guideline: Daily iron and folic acid supplementation in pregnant women" (2012); systematic reviews on folate deficiency and its health consequences.

Folic Acid Excess – Symptoms and Possible Consequences

Although folic acid is essential for health, its excess can also lead to problems. Usually, this risk concerns supplementation in doses exceeding the recommended amount, especially in the form of synthetic folic acid.

Symptoms of Folic Acid Excess

• Gastrointestinal disturbances – nausea, bloating, abdominal pain
• Neurological problems – headaches, difficulty concentrating
• Sleep disturbances and hyperactivity
• Masking vitamin B12 deficiency – long-term high-dose folic acid supplementation may conceal megaloblastic anemia caused by B12 deficiency

Sources of Excess

Excess folic acid most often results from high-dose supplements, particularly above the recommended maximum daily intake (600 µg for adults, 800 µg in supplements for pregnant women, according to GIS guidelines).

Prevention

To avoid the effects of excess folic acid, supplementation should follow recommendations and doses should be discussed with a doctor or dietitian, especially for pregnant women or individuals taking other vitamin preparations.

Sources: National Institutes of Health (NIH) – Folate Fact Sheet; European Food Safety Authority (EFSA) – Tolerable Upper Intake Level for folate.

Folic Acid – Recommended Intake in Different Age Groups

Determining the folic acid standard is crucial for proper supplementation and health. Requirements vary depending on age, physiological status, and sex. Correct doses help maintain healthy folate levels and prevent deficiencies or excesses.

Adults

The recommended daily dose of folic acid for adults is 400 µg. This amount supports proper homocysteine metabolism, nervous system function, and red blood cell production.

Pregnant Women

Pregnant women should supplement folic acid at a dose of 400–800 µg per day to reduce the risk of neural tube defects in the fetus. GIS guidelines state that in supplements dedicated to pregnant women, the maximum amount is 800 µg.

Children and Adolescents

• Newborns and infants: 65–80 µg/day
• Children 1–3 years: 150 µg/day
• Children 4–8 years: 200 µg/day
• Adolescents 9–13 years: 300 µg/day
• Adolescents 14–18 years: 400 µg/day

Older Adults

For individuals over 50 years old, a dose of 400 µg/day is usually sufficient, but it is important to monitor vitamin B12 levels, as excess folic acid can mask B12 deficiency.

Knowing the folic acid standard allows effective planning of supplementation and a folate-rich diet, which is crucial for overall health.

Folic Acid – In What Foods Does It Occur?

Folic acid, also known as vitamin B9, naturally occurs in many food products. Knowing folate sources allows you to supplement your diet even without supplements, although in some cases supplementation is necessary.

Foods Rich in Folic Acid

• Green leafy vegetables: spinach, lettuce, kale, arugula
• Legumes: lentils, chickpeas, beans, peas
• Fruits: oranges, avocado, bananas, strawberries
• Nuts and seeds: sunflower seeds, almonds, walnuts
• Whole grain products: oatmeal, buckwheat, brown rice
• Liver and animal products: chicken liver, eggs

Practical Notes

Folic acid in food is in its natural form, i.e., folates, which are less stable and partially lost during cooking. Therefore, a varied diet is recommended, and during periods of increased demand (pregnancy, planning pregnancy, deficiencies), supplementation with folic acid or 5-MTHF may be considered.

Folic Acid – Testing Levels and Supplementation

Monitoring folic acid levels in the body can help assess the risk of deficiencies and the effectiveness of supplementation. Testing usually involves measuring folate concentration in the blood (plasma or serum) and allows adjustment of the appropriate vitamin B9 dose.

When Is Testing Recommended?

• Planning pregnancy or during pregnancy – to ensure proper folate levels for fetal development
• Symptoms of deficiency – fatigue, weakness, megaloblastic anemia
• Chronic diseases or malabsorption disorders – e.g., celiac disease, intestinal disorders
• High-dose supplementation – to avoid excess

Approximate Cost of Testing

In Poland, the cost of measuring folic acid levels in commercial laboratories usually ranges from 30 to 70 PLN. Testing can also be performed as part of some preventive health packages or with a doctor's referral.

Folic Acid Supplementation

Supplementation is particularly recommended for women planning pregnancy and during pregnancy, individuals with deficiencies, and patients with limited dietary folate intake. Available supplement forms include:

• Synthetic folic acid – usually in tablets, doses from 200 to 800 µg
• 5-MTHF (methylated folic acid) – biologically active form, recommended for people with MTHFR gene mutations or conversion issues

Proper supplementation helps maintain folate levels within the normal range and prevents deficiencies or their health consequences.

Sources: National Institutes of Health (NIH) – Folate Fact Sheet; WHO – recommendations for folic acid supplementation during pregnancy; reviews of studies on measuring folate levels in the blood.

Summary – Key Information About Folic Acid

• Folic acid (vitamin B9) is essential for DNA production, cell division, and red blood cell formation.
• 5-MTHF is the active form of folic acid, better absorbed in people with MTHFR gene mutations.
• Benefits of folic acid: supports fetal development, red blood cell production, homocysteine metabolism, nervous system function, and cell regeneration.
• Folic acid in pregnancy: reduces the risk of neural tube defects in the child; recommended dose: 400–800 µg/day.
• Folic acid deficiency: manifests as fatigue, megaloblastic anemia, concentration problems, and may increase the risk of birth defects.
• Excess folic acid: rare, usually due to high-dose supplementation; symptoms: gastrointestinal disturbances, headaches, masking B12 deficiency.
• Recommended intake: adults 400 µg/day, children and adolescents 65–400 µg/day depending on age, pregnant women 400–800 µg/day.
• Dietary sources of folic acid: green leafy vegetables, legumes, fruits, nuts, whole grains, liver, and eggs.
• Testing and supplementation: it is worth monitoring blood folate levels when planning pregnancy, experiencing deficiency symptoms, or taking high-dose supplements; supplements are available as folic acid or 5-MTHF.