Folate (B9)

Water-soluble · DNA building

What does Folate (B9) do in your body?

Needed to make DNA and divide cells — critical before and during early pregnancy.

How it works, step by step

1. Folate is absorbed and converted to active forms.
2. It hands one-carbon units to DNA-building reactions.
3. With vitamin B12, it recycles homocysteine to methionine.
4. Dividing cells can now copy DNA correctly.

What does Folate (B9) do?

Carries one-carbon units used to build DNA and RNA and to recycle homocysteine into methionine.

Where does Folate (B9) act in the body?

Every dividing cell — especially bone marrow (blood cells) and a developing embryo.

Which foods contain Folate (B9)?

Leafy greens, legumes, asparagus, citrus; folic acid in fortified bread, flour and cereals.

How much Folate (B9) do adults need?

RDA: 400 mcg DFE for adults; 600 mcg DFE in pregnancy. Upper limit: 1,000 mcg/day of folic acid from supplements and fortified food.

What happens with too little Folate (B9)?

Can cause megaloblastic anemia. Low intake around conception raises the risk of neural tube defects.

Can you get too much Folate (B9)?

High folic acid can mask the anemia of vitamin B12 deficiency while nerve damage continues.

What does Folate (B9) interact with?

Works closely with vitamin B12. Methotrexate and some anticonvulsants interfere with folate.

What is known and unknown about Folate (B9)?

Folic acid before and in early pregnancy reduces neural tube defects — one of nutrition's clearest public health wins.

Evidence & sources

• US public health guidance (CDC, USPSTF) recommends 400 mcg of folic acid daily for people who could become pregnant, to help prevent neural tube defects. Evidence: strong. Known: Recommendation based on randomized trials and population fortification data. Unknown: — Source: US Centers for Disease Control and Prevention, Folic Acid — Recommendations (Current revision).

Connected topics

• Vitamin B12
• Lentils
• Spinach
• Blood
• Inside a Cell

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General education only, not medical advice. Drafted Oct 2026 · pending qualified expert review.