English version in progress: interface and data are in English; some explanatory text is still in Chinese.
Vitamin B9 (folate)
叶酸（folic acid）要在体内转化成四氢叶酸才能用；它提供"一碳单位"，参与 DNA 合成。
Full ranking Dose tool Products (5,027)
Key facts
Daily Value (US FDA)400 mcg
Tolerable Upper Intake Level (UL)1,000 mcg
Median（Per day）400 mcgP5 50 – P95 1,200
Products5,027
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; hard_high=20000 per serving (UL x10 or market maximum), hard_low=DV/1000
How it works：叶酸和"活性叶酸"有什么不同？
- 补剂和强化食品中的叶酸（folic acid）比食物中的天然叶酸盐吸收更好，标签用 DFE（膳食叶酸当量）统一换算。
- 在体内转化为四氢叶酸（THF）及其衍生物，例如 5-甲基四氢叶酸。
- 四氢叶酸作为一碳单位的载体，参与 DNA 和 RNA 合成，对快速分裂的细胞很重要。
- 它和 B12 一起把同型半胱氨酸转化为甲硫氨酸。
Schematic only; positions and scale are not anatomical.
Limits and cautions：成人叶酸（folic acid，补剂与强化食品）UL 为 1,000 mcg/天；高剂量可能掩盖 B12 缺乏。
Daily dose across products（mcg/day）
DV 400
UL 1,000
20 mcglog scale · n=5,0275,344 mcg
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 | — |
Top ranked
| Rank | Brand | Product | Per day | Score |
|---|---|---|---|---|
| 1 | Bulletproof | Methyl Folate | 800 mcg | 90.0 |
| 2 | Swanson | Folate 5-Methyltetrahydrofolic Acid 800 mcg | 800 mcg | 88.0 |
| 3 | Genestra Brands | Active Folate 1000 | 1,000 mcg | 85.0 |
| 3 | Doctor's Best | Fully Active Folate 800 mcg | 800 mcg | 85.0 |
| 3 | Jarrow Formulas | Methyl Folate 400 mcg | 400 mcg | 85.0 |
For information only; not medical advice. Talk to a doctor or pharmacist before starting or stopping any supplement.