Folic acid – a term many people know primarily from pregnancy. But what exactly is folic acid, why are so many people deficient in it – and why is it important to pay attention to the right form when supplementing?
What is folic acid – and what is folate?
Folic acid is the synthetic form of vitamin B9, used in many dietary supplements and fortified foods. In nature, however, B9 occurs in its active, natural form as folate – for example, in green leafy vegetables, legumes, and liver.
Folate is essential for many vital processes in the body:
- Cell division and tissue formation
- DNA synthesis and repair
- Blood formation
- Homocysteine metabolism (together with vitamins B6 and B12)
- Protection of nerves and brain function
Why so many people have a folic acid deficiency
Although we in industrialized nations seem to be well supplied with folate, functional folate deficiency is surprisingly common. Here are the main causes:
- Genetic mutations (for example, MTHFR C677T):
Many people – estimated at around 30–50 percent in Central Europe – carry variants in the MTHFR gene. This mutation weakens the enzyme responsible for converting folic acid into its active form, 5-methyltetrahydrofolate (5-MTHF). As a result, folic acid remains unused in the blood, while the cells remain deficient. - Food processing and heating:
Natural folates are very sensitive to heat and light. Up to 90 percent of the original content can be lost during cooking, frying, or prolonged storage. - Unbalanced diet:
Many people eat too little fresh vegetables or resort to highly processed products. This significantly reduces the intake of active folates. - Medications, alcohol, stress, pregnancy,
birth control pills, certain antiepileptic drugs, or frequent alcohol consumption impair folate absorption. The need for folate is also significantly increased during pregnancy and breastfeeding.
Why you shouldn’t use synthetic folic acid
The conventional folic acid found in many supplements is not immediately bioactive. It must first be activated in the body in several steps:
- Folic acid → Dihydrofolate (DHF)
- DHF → Tetrahydrofolate (THF)
- THF → 5-methyltetrahydrofolate (5-MTHF)
This conversion requires the enzyme MTHFR – and this enzyme is impaired in many people. Particularly in genetic variants like MTHFR C677T, activation can be reduced by up to 70 percent.
The hidden danger: Unmetabolized folic acid
If synthetic folic acid is not completely converted, it accumulates in the blood as “unmetabolized folic acid.” This can lead to problems:
- Blocking of folate receptors: Synthetic folic acid can bind to receptors without being biologically active – thus preventing the absorption of active folate.
- Functional deficiency despite “normal” blood values.
- Disruptions in cell division, DNA repair, and methylation.
Therefore, make sure to only supplement with active folic acid.