Vitamin B9 (folate)
Folic acid must be converted to tetrahydrofolate in the body before use; it supplies one-carbon units for DNA synthesis.
Full ranking Dose tool Products (5,027)
Key facts
Sources: https://ods.od.nih.gov/factsheets/Folate-HealthProfessional/ · FDA DV 400 mcg (https://www.fda.gov/food/nutrition-facts-label/daily-value-nutrition-and-supplement-facts-labels); pre-2016 DV [] (https://www.federalregister.gov/documents/2016/05/27/2016-11867/food-labeling-revision-of-the-nutrition-and-supplement-facts-labels); adult UL 1000 mcg
How it works: How is folic acid different from "active folate"?
- Folic acid in supplements and fortified foods is absorbed better than natural food folate; labels use DFE (dietary folate equivalents) to put them on one scale.
- The body converts it to tetrahydrofolate (THF) and its derivatives, such as 5-methyltetrahydrofolate.
- THF carries one-carbon units for DNA and RNA synthesis, which matters for rapidly dividing cells.
- Together with B12 it converts homocysteine to methionine.
Schematic only; positions and scale are not anatomical.
Sources: NIH ODS: Folate Fact Sheet for Health Professionals
Daily dose across products (mcg/day)
Label data from official national databases and brand websites, as declared; not lab-verified.
Common forms
| Form | Products | Median | P5–P95 | Elemental fraction |
|---|---|---|---|---|
| Folic acid | 2992 | 400 mcg | 50 – 1,000 | — |
| L-5-Methyltetrahydrofolate (5-MTHF) | 1624 | 400 mcg | 50 – 1,666 | — |
| Folinic acid | 142 | 400 mcg | 50 – 1,000 | — |
Common questions
What is the Daily Value for Vitamin B9 (folate)?
The US FDA Daily Value for adults and children aged 4 and over is 400 mcg. It is a labelling reference, not a personal recommendation. [source]
Is there an upper limit for Vitamin B9 (folate)?
The adult Tolerable Upper Intake Level (UL) is 1,000 mcg per day. Going above it long term raises the risk of adverse effects. See the linked source. [source]
How much Vitamin B9 (folate) do products usually contain per day?
As of 2026-11-01, 5,027 products list a comparable daily dose (6,574 dose records; one product can have several). The median is 400 mcg per day, and 90% of records fall between 50 and 1,200 mcg. Figures come from labels and are not lab-tested. [source]
How is folic acid different from "active folate"?
Folic acid must be converted to tetrahydrofolate in the body before use; it supplies one-carbon units for DNA synthesis. Adult UL for folic acid (from supplements and fortified foods): 1,000 mcg per day; high doses can mask B12 deficiency. [source]
What are the side effects of Vitamin B9 (folate)?
Folate naturally in food is not harmful. Folate from supplements and fortified foods should not exceed the upper limit unless a health care provider advises it. (Source: NIH ODS) [source]
What happens if you take too much Vitamin B9 (folate)?
The adult UL for folate from supplements and fortified foods is 1,000 mcg a day. Large doses can hide vitamin B12 deficiency: they fix the anemia but not the nerve damage, which can become permanent. High doses may also raise colorectal cancer risk in some people. (Source: NIH ODS) [source]
Is Vitamin B9 (folate) safe during pregnancy and breastfeeding?
The recommended amount is 600 mcg DFE a day in pregnancy and 500 mcg DFE while breastfeeding. All women who could become pregnant should get 400 mcg of folic acid a day from supplements, fortified foods or both (folic acid, not 5-MTHF, even with an MTHFR C677T variant) to help prevent neural tube defects. (Source: NIH ODS) [source]
Does Vitamin B9 (folate) interact with medications or other supplements?
Folate supplements could interfere with methotrexate used for cancer. Antiseizure drugs such as phenytoin, carbamazepine and valproate can lower blood folate, and folate supplements can lower blood levels of these drugs. Sulfasalazine can reduce folate absorption. (Source: NIH ODS) [source]
Top ranked
| Rank | Brand | Product | Per day | Score |
|---|---|---|---|---|
| 1 | Bulletproof | Methyl Folate | 800 mcg | 100.0 |
| 2 | Swanson | Folate 5-Methyltetrahydrofolic Acid 800 mcg | 800 mcg | 97.8 |
| 3 | Genestra Brands | Active Folate 1000 | 1,000 mcg | 94.4 |
| 3 | Doctor's Best | Fully Active Folate 800 mcg | 800 mcg | 94.4 |
| 3 | Jarrow Formulas | Methyl Folate 400 mcg | 400 mcg | 94.4 |