Folic acid is the stable synthetic form of vitamin B9 (also called folate in its natural dietary form), a water-soluble vitamin of the B complex with a particularly critical role in preconception and pregnancy (prevention of neural tube defects in the fetus). It contributes to normal amino acid synthesis, to normal formation of red blood cells, to normal psychological function, to the normal function of the immune system, to the reduction of tiredness and fatigue and to 2 further physiological functions officially authorized at the European level. This page covers how it works, the commercial forms (folic acid, folate, methylfolate), the studied doses and where it fits within the Pleniage portfolio.
What is folic acid (vitamin B9)?
The name folate covers a family of chemically related compounds that make up vitamin B9. The term comes from the Latin folium ("leaf"), because of the abundance of this vitamin in the green leafy vegetables where it was first identified. It is an essential water-soluble vitamin: the body cannot synthesize it and must obtain it through the diet or through food supplements.
The terminological distinction is relevant in practice:
- Folate: the natural form present in foods (green leafy vegetables, legumes, liver).
- Folic acid: the stable synthetic form used in food supplements and in fortified foods. It is the form historically most studied in clinical research and in public health policy.
- Methylfolate (5-MTHF): the active coenzyme form into which the body converts both folate and folic acid before using them. Also available as a direct supplement form.
The fundamental biological function of folate is to participate in the synthesis of DNA and RNA (components of the genetic material) and in the regulation of the methyl cycle, two processes that are critical in cell division and in numerous biochemical reactions of the body.
What is it for? Functions authorized at the European level
At the European level, the EFSA (European Food Safety Authority) has officially authorized seven health claims for folate/folic acid. These claims may be used in the labeling and communication of food supplements that provide at least 15% of the nutrient reference value (NRV) per recommended dose.
Normal synthesis of amino acids and DNA
Folate contributes to normal amino acid synthesis (authorized EFSA claim, ID 79). This function reflects its role in the methyl cycle and in the transfer of one-carbon units, both involved in the synthesis and modification of amino acids and DNA.
Normal formation of red blood cells
Folate contributes to normal formation of red blood cells (authorized EFSA claim, ID 80). Severe folate deficiency produces a characteristic type of anemia (megaloblastic anemia), with a pattern similar to vitamin B12 deficiency.
Normal homocysteine metabolism
Folate contributes to normal homocysteine metabolism (authorized EFSA claim, ID 81). In synergy with vitamin B12 and vitamin B6, folate participates in the cycle of remethylation of homocysteine to methionine.
Psychological function, immune system and tiredness
- Normal psychological function (authorized EFSA claim, ID 82).
- Normal function of the immune system (authorized EFSA claim, ID 83).
- Reduction of tiredness and fatigue (authorized EFSA claim, ID 84).
Process of cell division
Folate contributes to the process of cell division (authorized EFSA claim, ID 85). This function is the biological basis of its critical role in tissues with a high turnover rate (bone marrow, intestinal mucosa) and, especially, in embryonic and fetal development where cell division is massive.
Specific claim on the neural tube during pregnancy
Folic acid has an additional specific EFSA claim: supplemental folic acid intake increases maternal folate status, and low maternal folate status is a risk factor in the development of neural tube defects in the developing fetus (authorized EFSA claim, ID 827). This is the only "green" EFSA claim that applies specifically to a concrete clinical indication (preconception and the first weeks of pregnancy) and is based on decades of robust evidence. Further on (in a dedicated section) we go deeper into this function.
How it works: the folate cycle and DNA synthesis
Folate and its derivatives act as cofactors in what is called the folate cycle, a series of biochemical reactions that transfer one-carbon units (methyl, formyl, methylene groups) to substrate molecules. The key functions include:
- Synthesis of purines and pyrimidines, the components of DNA and RNA.
- Synthesis of thymine, a nucleotide base essential for DNA replication.
- The methyl cycle, together with vitamin B12: the active form of folate (5-MTHF) donates its methyl group to regenerate methionine from homocysteine. This synergy with B12 explains why a deficiency of either of the two vitamins produces similar alterations in DNA synthesis.
The synergy with vitamin B12 is biochemically obligatory and clinically important: when there is B12 deficiency, folate becomes trapped in its methylated form (the "methyl trap"), unable to participate in the synthesis of purines. For this reason, diagnostic tests and the supplementation of deficiencies must consider both vitamins together: giving folate without correcting an underlying B12 deficiency may mask the anemia but not the neurological manifestations of B12 deficiency.
Natural folate vs folic acid vs methylfolate
The distinction between forms has growing practical relevance:
| Form | Origin | Notes |
|---|---|---|
| Natural folate | Foods (green leafy vegetables, legumes) | Dietary form. Partially absorbed; the body converts it to 5-MTHF. |
| Folic acid (synthetic) | Supplements, food fortification | Historically the standard form in research and public health policy. Stable, inexpensive. Almost completely absorbed and converted to 5-MTHF in the intestine and liver. |
| Methylfolate (5-MTHF) | Specialized supplements (Quatrefolic®, Metafolin®) | Directly usable active form. Of particular interest in people with polymorphisms of the MTHFR gene (~10% of the population are homozygous) that reduce the efficiency of conversion of folic acid to 5-MTHF. |
Most of the reference clinical trials, including the evidence supporting the EFSA claim on neural tube defects, have been carried out with synthetic folic acid, which is the standard form in European supplementation and in the mandatory fortification of flours in many countries. Methylfolate is a more recent alternative of interest in specific profiles (MTHFR polymorphisms, individual sensitivity).
Food sources and daily needs
Natural folate is found above all in:
- Dark green leafy vegetables (spinach, chard, kale).
- Broccoli, cauliflower and other cruciferous vegetables.
- Legumes (lentils, chickpeas, beans, soy).
- Animal liver: especially high contents.
- Asparagus, avocado, beetroot.
- Whole grains and, in many countries, cereals fortified with folic acid.
- Nuts and seeds (peanuts, sunflower seeds).
The nutrient reference value (NRV) in the European Union for folate is 200 μg/day of dietary folate equivalents (EU Regulation 1169/2011). International recommendations for adults are around 400 μg/day (DFE) according to the US National Academies; women of childbearing age who may become pregnant require a specific additional intake (see the following section).
Natural folate is heat-labile (it partially degrades with heat and with prolonged cooking times in water). Short cooking or raw consumption (when it is safe) better preserves the content.
Preconception and pregnancy: the best-established clinical case
This section deserves dedicated treatment because of its clinical relevance.
Supplementation with folic acid in the preconception period and in the first weeks of pregnancy is one of the public health interventions with the most solid accumulated scientific evidence over recent decades. Folate deficiency during the closure of the neural tube (which occurs between days 17-30 post-conception, frequently before the woman knows she is pregnant) is associated with a significant increase in the risk of congenital neural tube defects (spina bifida, anencephaly and other anomalies).
The specific EFSA claim (ID 827) recognizes this function. The recommendations of the main obstetric societies and of the European Ministries of Health coincide:
- Women of childbearing age who may become pregnant should routinely receive an additional intake of 400 μg/day of folic acid, from at least 1 month before conception and during the first trimester of pregnancy.
- In specific clinical contexts (family or personal history of neural tube defects, certain antiepileptic treatments, diabetes mellitus, obesity) the recommended doses are significantly higher and must be prescribed under medical supervision.
This specific indication corresponds to preconception clinical supplementation under medical/gynecological follow-up, not to general maintenance supplementation within the B complex.
Deficiency and at-risk populations
Folate deficiency may manifest as megaloblastic anemia (similar to B12 deficiency) and, during critical developmental periods (pregnancy), as congenital malformations. The populations at greatest risk of deficiency include:
- Women of childbearing age with a non-varied diet or without regular access to green leafy vegetables.
- People with high alcohol consumption: chronic alcoholism interferes with the absorption and metabolism of folate.
- People on chronic antiepileptic treatment (carbamazepine, phenytoin, valproic acid) or on certain antineoplastics (methotrexate, a folate antagonist): these may induce a functional deficiency.
- People with chronic digestive diseases (untreated celiac disease, inflammatory bowel disease): intestinal malabsorption.
- People with relevant polymorphisms of the MTHFR gene (~10% of the population are homozygous C677T): lower efficiency of conversion to 5-MTHF; they may benefit from direct methylfolate supplements.
Doses and forms of supplementation
The usual supplementation doses are:
- General maintenance: 200-400 μg/day (covers the European NRV plus a moderate additional intake).
- Women of childbearing age with the possibility of pregnancy: 400 μg/day routinely.
- Preconception period + first trimester of pregnancy: 400 μg/day as a baseline, with possible higher adjustments under medical supervision.
- Specific clinical indications: significantly higher doses under medical supervision.
EFSA has established a tolerable upper intake level (UL) of 1,000 μg/day (1 mg/day) of folic acid from food supplements and fortified foods, based on safety considerations regarding the potential masking of B12 deficiency at higher doses.
Safety and interactions
Folic acid has a very favorable safety profile at the usual doses. The most important precaution at high doses is the potential masking of B12 deficiency: high doses of folic acid can correct the anemia associated with B12 deficiency without correcting the neurological manifestations, which may progress while the hematological blood work appears normal. For this reason, doses ≥1,000 μg/day (EFSA UL) require parallel screening of B12 status and medical supervision.
Relevant pharmacological interactions
- Antiepileptics (carbamazepine, phenytoin, valproic acid): these may reduce folate levels and, reciprocally, high doses of folate may modify antiepileptic levels. People on antiepileptic treatment who plan a pregnancy require specialized management.
- Methotrexate and folate antagonists (rheumatoid arthritis, oncology): folic acid may modify their efficacy. Management under medical supervision.
- Sulfasalazine, trimethoprim: these may interfere with folate metabolism.
How to choose a folic acid supplement
- Form according to objective: synthetic folic acid for general use and for the preconception/pregnancy indication (the standard form in evidence and public policy); methylfolate (5-MTHF) for people with known MTHFR polymorphisms or individual sensitivity.
- Consistent dose: 200-400 μg/day for general maintenance; 400 μg/day from the moment pregnancy is being planned.
- Consistency with the B complex: supplementation with folate as a stand-alone supplement is only specifically indicated in preconception/pregnancy (where the dose is routine) or by medical prescription; in all other contexts the consistent approach is as part of a B complex.
- Attention to B12 status: especially in older people, people on a vegetarian/vegan diet or with chronic treatments that affect B12 absorption.
Folic acid in the Pleniage portfolio
In the formulation of PLENIAGE® ENERGY PRO, folic acid forms part of the complete B complex (B1, B2, B3, B5, B6, B12) incorporated together with magnesium citrate, alpha-lipoic acid (175 mg), vitamin C, vitamin E and biotin. The formula is designed to provide the B-group vitamins in a coordinated way, in synergy with cofactors and antioxidants involved in cellular energy metabolism. Each ingredient has its own individual scientific research and, in the case of folic acid, seven officially authorized claims at the European level in addition to the specific claim on the neural tube (ID 827); the specific combination of this formula has not been the subject of its own clinical trial. Women of childbearing age who plan a pregnancy should consult their doctor to assess whether the folic acid dose of a generic B complex is adequate or whether specific preconception supplementation is required.
This page is part of the Energy and performance cluster. To go deeper into other related components, see the Vitamin B12 page (direct biochemical synergy in the methyl cycle) and the Vitamin B5 page.
Frequently asked questions about folic acid
Are folate and folic acid the same thing?
They are the same vitamin (B9) in different forms. Folate is the natural form present in foods (green leafy vegetables, legumes, liver). Folic acid is the stable synthetic form used in food supplements and in fortified foods. Methylfolate (5-MTHF) is the active coenzyme form into which the body converts both folate and folic acid before using them.
Why is folic acid recommended before and during pregnancy?
Because folate deficiency during the closure of the neural tube (days 17-30 post-conception, before many women know they are pregnant) is associated with a significant increase in the risk of congenital neural tube defects (spina bifida, anencephaly). The EFSA claim ID 827 recognizes this function. The European recommendations: 400 μg/day of folic acid from at least 1 month before conception and during the first trimester, in women of childbearing age who may become pregnant. Consult your doctor/gynecologist for your specific case.
How much vitamin B9 do I need per day?
The NRV in the European Union is 200 μg/day; international recommendations for adults are around 400 μg/day. Women of childbearing age with the possibility of pregnancy should routinely receive 400 μg/day of folic acid. EFSA has established a tolerable upper intake level (UL) of 1,000 μg/day from food supplements and fortified foods.
What is the MTHFR polymorphism and when is methylfolate advisable?
The MTHFR gene encodes a key enzyme in the conversion of folic acid to its active form (5-MTHF). Approximately 10% of the population is homozygous for a variant (C677T) that reduces the efficiency of this conversion. In these people, supplementing with methylfolate (5-MTHF) directly may have theoretical advantages over synthetic folic acid. Determining the MTHFR genotype is not routine and requires a specific medical indication.
Why can folic acid mask B12 deficiency?
Because the anemias associated with folate deficiency and with B12 deficiency are both megaloblastic and have a similar laboratory pattern. High doses of folic acid can correct the hematological part of B12 deficiency without correcting the neurological manifestations, which may progress while the blood work appears normal. For this reason, doses ≥1,000 μg/day (EFSA UL) require parallel screening of B12 status.
Does folic acid have contraindications?
It has a very favorable safety profile at the usual doses. Specific precautions: people on chronic antiepileptic treatment who plan a pregnancy require specialized management (bidirectional interaction). People on methotrexate treatment (rheumatoid arthritis, oncology) should coordinate supplementation with their doctor. Supplementation with high doses requires screening of B12 status to avoid masking.
Is natural folate preserved when cooking?
Only partially. Folate is heat-labile and degrades with heat and with prolonged cooking times in water. Brief steaming or sautéing, or raw consumption when it is safe (salads), better preserves the content. Fresh green leafy vegetables and raw nuts are the sources that best maintain dietary folate.
Folic acid is the stable synthetic form of vitamin B9 (natural folate in foods). It has seven authorized "green" EFSA claims (amino acid synthesis, formation of red blood cells, homocysteine metabolism, psychological function, immune system, tiredness and fatigue, cell division) plus a specific claim on the neural tube in preconception/pregnancy (ID 827). Its most solid clinical evidence supports preconception use to reduce the risk of neural tube defects. The synergy with vitamin B12 is biochemically obligatory and clinically important. For general maintenance, the usual supplementation is within the B complex; women of childbearing age with the possibility of pregnancy should ensure a specific intake of 400 μg/day from at least 1 month before conception.
At PLENIAGE® we publish scientific content on evidence-based supplementation. You can explore the Energy and performance cluster for more pages and related articles.
References
The statements in the article are based on available scientific literature and on the health claims officially authorized by EFSA.
- EFSA Health Claims Register — folate/folic acid: authorized claims ID 79 (amino acid synthesis), 80 (formation of red blood cells), 81 (homocysteine metabolism), 82 (psychological function), 83 (immune system), 84 (tiredness and fatigue), 85 (cell division), 827 (neural tube defects in pregnancy). Official source: EU Register of Nutrition and Health Claims.
- EU Regulation 1169/2011 on food information to consumers — Annex XIII (NRV for folate: 200 μg/day). EFSA UL for supplements: 1,000 μg/day.
- Bailey LB, Stover PJ, McNulty H, et al. Biomarkers of nutrition for development-folate review. J Nutr. 2015;145(7):1636S-1680S. PMID: 26451605.
- De-Regil LM, Peña-Rosas JP, Fernández-Gaxiola AC, Rayco-Solon P. Effects and safety of periconceptional oral folate supplementation for preventing birth defects. Cochrane Database Syst Rev. 2015;(12):CD007950. PMID: 26662928.
- Smith AD, Smith SM, de Jager CA, et al. Homocysteine-lowering by B vitamins slows the rate of accelerated brain atrophy in mild cognitive impairment: a randomized controlled trial. PLoS One. 2010;5(9):e12244. PMID: 20838622.