Folat und Folsäure: Warum dieses Vitamin so wichtig ist

Folat kommt natürlich in Lebensmitteln vor, während Folsäure die synthetische Form ist, die in Nahrungsergänzungsmitteln und angereicherten Lebensmitteln verwendet wird. Folsäure wird vom Körper effektiver aufgenommen.

Dunkelgrünes Blattgemüse (Spinat, Romanasalat), Hülsenfrüchte, Avocado, Spargel und Zitrusfrüchte sind reich an Folat. Angereicherte Getreideprodukte sind ebenfalls wichtige Quellen.

Schwangere Frauen (oder Frauen, die eine Schwangerschaft planen) haben einen erhöhten Bedarf. Die empfohlene Tagesdosis steigt von 400 µg auf 600 µg. Folsäure-Supplemente werden vor der Empfängnis empfohlen.

Ein Folatmangel kann zu Anämie und bei Schwangeren zu Neuralrohrdefekten beim Baby führen. Eine Überdosierung aus Lebensmitteln ist unwahrscheinlich, aus Supplementen jedoch möglich.

The evidence linking folate status to neural tube defect prevention is among the most robust in nutritional epidemiology. The landmark MRC Vitamin Study, published in 1991, demonstrated that supplementation with 4mg of folic acid in women at high risk of neural tube defect recurrence reduced incidence by 72%. Subsequent studies in general populations confirmed that daily supplementation with 400mcg reduces the risk of first-time neural tube defects by approximately 50–70%. Because neural tube closure is complete by day 28 of embryonic development — before most women realise they are pregnant — current guidelines in most countries recommend that all women who could become pregnant take 400mcg of folic acid daily, or consume equivalent amounts through fortified foods. Women with a previous neural tube defect-affected pregnancy, those with the MTHFR TT genotype, those taking anti-epileptic medications that interfere with folate metabolism, or those with diabetes or obesity are typically recommended higher doses of 4–5mg daily under medical supervision. Beyond neural tube defects, higher folate intake during pregnancy is associated with reduced risks of cleft palate, congenital heart defects, and preterm birth in observational studies. Adequate folate also supports placental development and the extraordinary cell division demands of the first trimester. Some researchers argue that the current population recommendation of 400mcg may be insufficient for women with impaired folate metabolism and that 5-MTHF at comparable doses may be a more appropriate universal recommendation, particularly given the MTHFR variant prevalence. This remains an area of active scientific debate.

The supplement market offers several forms of vitamin B9: folic acid (the conventional synthetic form), folinic acid (5-formyltetrahydrofolate, also called leucovorin), and methylfolate (5-methyltetrahydrofolate or 5-MTHF), the latter sold under brand names including Metafolin and Quatrefolic. For the general population without known MTHFR variants, standard folic acid at 400mcg daily remains the evidence-based recommendation during reproductive years, supported by decades of safety and efficacy data. Concerns about UMFA at this dose are theoretically plausible but not yet demonstrated to cause measurable harm in most people. For those with MTHFR C677T homozygosity or with a personal or family history of neural tube defects, methylfolate (5-MTHF) is a logical choice: it bypasses the rate-limiting enzymatic step, does not produce UMFA, and is available in supplements ranging from 400mcg to 15mg. Starting at standard doses (400–800mcg) and increasing only under guidance is prudent, as some people with severely impaired methylation report paradoxical reactions to high-dose methylfolate. Folinic acid is sometimes used as an intermediate option for those who react to methylfolate. B-complex supplements typically provide folic acid; those wishing to switch to methylfolate need to specifically seek formulations listing 5-MTHF or methylfolate. For most people eating diets rich in legumes, leafy greens, and fortified foods, supplementation may be unnecessary outside pregnancy and conception planning — but given the prevalence of suboptimal intake in Western diets, a standard multivitamin containing 400mcg of folate is a reasonable low-risk insurance policy for most adults.