English version in progress: interface and data are in English; some explanatory text is still in Chinese.
Vitamin D
它本身没有活性，要先后在肝脏和肾脏各"加工"一次，才变成能帮肠道吸收钙的形式。
Full ranking Dose tool Products (5,334)
Key facts
Daily Value (US FDA)20 mcg
Tolerable Upper Intake Level (UL)100 mcg
Median（Per day）12.5 mcgP5 2.5 – P95 64
Products5,334
Sources: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/ · FDA DV 20 mcg (https://www.fda.gov/food/nutrition-facts-label/daily-value-nutrition-and-supplement-facts-labels); pre-2016 DV [10] (https://www.federalregister.gov/documents/2016/05/27/2016-11867/food-labeling-revision-of-the-nutrition-and-supplement-facts-labels); adult UL 100 mcg; hard_high=2500 per serving (UL x10 or market maximum), hard_low=DV/1000
How it works：维生素 D 吃进去以后，要经过哪几步才起作用？
- 皮肤受 UVB 照射合成维生素 D，或从食物和补剂吸收。此时它还没有生物活性。
- 肝脏把它转化为 25(OH)D。血液检测看的就是这个指标。
- 肾脏再把 25(OH)D 转化为活性形式 1,25(OH)₂D（骨化三醇）。
- 活性形式促进小肠吸收钙和磷。
- 血钙、血磷维持在正常范围，骨骼才能正常矿化。
Schematic only; positions and scale are not anatomical.
Limits and cautions：成人可耐受最高摄入量（UL）为 100 mcg（4,000 IU）/天；长期超量可致高钙血症。
Sources：NIH ODS: VitaminD Fact Sheet for Health Professionals
Daily dose across products（mcg/day）
DV 20
UL 100
0.83 mcglog scale · n=5,334225 mcg
Label data from official national databases and brand websites, as declared; not lab-verified.
Common forms
| Form | Products | Median | P5–P95 | Elemental fraction |
|---|---|---|---|---|
| Vitamin D3 (cholecalciferol) | 4939 | 15 mcg | 2.5 – 75 | — |
| Vitamin D2 (ergocalciferol) | 298 | 10 mcg | 1.25 – 25 | — |
Top ranked
| Rank | Brand | Product | Per day | Score |
|---|---|---|---|---|
| 1 | Nordic Naturals | Plant-Based Vitamin D3 Liquid | 25 mcg | 90.0 |
| 1 | The Vitamin Shoppe | Vitamin D3 | 25 mcg | 90.0 |
| 1 | Nordic Naturals | Vitamin D3 + K2 Gummies Pomegranate | 25 mcg | 90.0 |
| 1 | Nordic Naturals | Vitamin D3 1000 | 25 mcg | 90.0 |
| 5 | Vitamin World | Sunvite Chewable Vitamin D3 1000 IU | 25 mcg | 88.0 |
For information only; not medical advice. Talk to a doctor or pharmacist before starting or stopping any supplement.