Folate and folic acid are both forms of vitamin B9, but not identical: folate is the naturally occurring form in foods, while folic acid is the synthetic form used in supplements and food fortification. Folic acid must be converted in the body to the active form (5‑MTHF); some people have reduced conversion. Adequate B9 prevents neural tube defects, so supplementation is recommended before and during early pregnancy.

Both are useful: folate is the natural form in foods; folic acid is the synthetic form used in supplements and fortification and effectively prevents neural-tube defects. Most people do well with standard folic acid supplements, but those with MTHFR gene variants may benefit from the active form (5‑MTHF). Pregnant or planning pregnancy should follow clinician advice on dose.

Folic acid is considered safe during breastfeeding. Lactating women need about 500 µg dietary folate equivalents daily; standard supplements (400–500 µg folic acid) are appropriate to maintain maternal stores and support infant development. Folic acid appears in breast milk at physiologic levels and hasn’t been shown to harm infants. Discuss higher doses (≥1 mg) or interactions (e.g., with antiepileptic drugs or B12 deficiency) with your clinician.

Folic acid generally does not cause heartburn in most people. It is usually well tolerated, though some users report mild gastrointestinal effects — nausea, bloating, gas or indigestion — which can feel like heartburn for sensitive individuals. Taking the supplement with food or at a different time may help. If reflux or persistent symptoms occur, stop the supplement and speak with your healthcare provider.

Vitamin B9 is commonly called folate when found naturally in foods and folic acid for the synthetic form used in supplements and fortified foods. It's also referred to as pteroylmonoglutamic acid in chemical contexts. Folate is essential for DNA synthesis, cell division and preventing neural tube defects in pregnancy; deficiency causes anemia and other health problems.

Folate supports DNA and RNA synthesis, healthy cell division, and red blood cell formation, helping prevent anemia. It’s essential in pregnancy to reduce neural tube defect risk and support fetal growth. Folate also helps metabolize homocysteine, which may benefit cardiovascular health, and contributes to normal energy metabolism and neurological function such as mood and cognitive performance.