A B vitamin essential for making DNA and red blood cells. Critical before and during early pregnancy to prevent serious birth defects of the brain and spine. The supplement form (folic acid) and the food form (folate) are not the same — and the difference matters for some people.

Recommended daily intake

Adults · 400 mcg DFE
Pregnancy · 600 mcg DFE
Lactation · 500 mcg DFE
Before Conception · 400-800 mcg daily, ideally starting one month before pregnancy

Upper intake limit

1,000 mcg/day from supplements and fortified foods (does not apply to folate from natural food sources)

Signs of deficiency

Megaloblastic anemia — fatigue, weakness, pale skin, shortness of breath
Mouth sores, swollen tongue
Difficulty concentrating, irritability
Elevated homocysteine on bloodwork
Increased risk of neural tube defects in pregnancy

Required to build and repair DNA
Essential for making red blood cells — deficiency causes a specific type of anemia
Critical in the first weeks of pregnancy to prevent neural tube defects like spina bifida
Works closely with vitamin B12 — deficiency in either creates similar symptoms
Supports normal homocysteine levels, which are linked to cardiovascular health
MTHFR enzyme.">Methylfolate (the active form) is preferred for people with MTHFR gene variants who don't convert folic acid efficiently

High-dose folic acid can mask a vitamin B12 deficiency, allowing nerve damage to progress quietly

Synthetic folic acid above 1,000 mcg/day may circulate unmetabolized — long-term effects are still being studied

Use caution with methotrexate (a chemotherapy and arthritis drug) and certain anti-seizure medications — folate can affect how they work

People with MTHFR gene variants may do better with methylfolate than folic acid

Pregnancy needs are higher than the standard adult RDA — start a prenatal vitamin before conception when possible

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