Convert vitamins A, D, E from IU to mg, μg, ppm in real-time and check daily recommended intake.
| Item | IU | Equivalent |
|---|---|---|
| For Adults | 3,000 IU | 900 μg |
| Upper Limit | 10,000 IU | 3,000 μg |
IU (International Unit) is a unit that measures the biological activity of vitamins. Since the same amount of vitamins can have different absorption rates and effects depending on their form, IU standardizes based on biological efficacy rather than weight (mg, μg). For Vitamin A, 1 IU = 0.3 μg retinol or 0.6 μg beta-carotene. For Vitamin D, 1 IU = 0.025 μg. For Vitamin E, 1 IU = 0.67 mg d-α-tocopherol or 1 mg dl-α-tocopherol.
Vitamin A is also expressed as Retinol Activity Equivalents (RAE). 1 RAE = 1 μg retinol = 12 μg beta-carotene = 24 μg other carotenoids. In IU, 1 RAE = 3.33 IU (retinol basis). Adult males need 900 μg RAE (3,000 IU) daily, adult females need 700 μg RAE (2,333 IU). The upper limit is 3,000 μg RAE (10,000 IU).
The daily recommended intake of Vitamin D is 600 IU (15 μg) for adults, 800 IU (20 μg) for those over 71. The upper limit is 4,000 IU (100 μg). 15-30 minutes of sunlight exposure synthesizes about 10,000-25,000 IU of Vitamin D in the body. Salmon (100g) contains about 400-800 IU, one egg yolk contains 40 IU.
Vitamin E is classified into natural d-α-tocopherol and synthetic dl-α-tocopherol. Natural form: 1 IU = 0.67 mg, synthetic form: 1 IU = 1 mg. Daily recommended intake for adults is 15 mg (22.4 IU natural or 33.3 IU synthetic). Almonds (28g, 23 nuts) contain about 7.3 mg (10.9 IU).
ppm (parts per million) is a concentration unit representing one part per million: 1 ppm = 1 mg/kg = 1 μg/g. It is used for food additives, pesticide residues, and heavy metal content. For example, if 1L of water (1kg) contains 100mg of Vitamin C, that is 100 ppm.
When choosing vitamin supplements, check form (natural/synthetic), content (IU/mg), and absorption rate. Vitamin A in retinol form has higher absorption than beta-carotene, but beta-carotene is safer due to toxicity concerns. Vitamin D3 has higher bioactivity than D2. Natural Vitamin E (d-α-tocopherol) has 2x higher bioavailability than synthetic forms.