You have a unique, individual need for each vitamin and mineral, depending on your gender, age, weight, level of activity and the metabolic pathways and enzyme systems you have inherited. Some people need more of certain micronutrients, while others need fewer.
Nutritional experts have therefore drawn up recommended daily amounts (RDAs) that are designed to meet the needs of just about everyone in the population. These food-based values are calculated statistically to encompass the requirements of 97.5% of the age range they cover.
Why are they knowingly set to be insufficient for 2.5% of the population? A good question! Essentially it’s because too much of some nutrients may cause problems for another 2.5% of the population, at the other end of the statistical scale, whose needs are unusually low. Intakes above 400 mg magnesium, for example, can lead to bowel looseness in some people (not always an undesirable trait, but this does limit magnesium intakes, the upper safe level for which is around 400 mg for supplements, in addition to values obtained from your food).
RDAs, NRVs and DVs for vitamins and minerals
Food supplements feature slightly different values, selected for labelling purposes, known as the NRV (Nutrient Reference Value) in the UK/EU, and the DV (Daily Value) in the US. Different criteria were used to define these, and the DV in particular is based on outdated recommendations made almost 50 years ago. The FDA has recently updated these, and the new values must appear on labels by mid 2020, although until then the old DVs may still feature.
The EU/UK Nutrient Reference Values and both the old and new US Daily Values for vitamins and minerals are shown in the tables below. You can find the new US DVs for adults, infants, children and pregnant or lactating women via the NIH Dietary Supplement Label Database.
NRVs and DVs for vitamins
| VITAMIN | UK/EU NRV | OLD US DV | NEW US DV (adults and children 4+) |
|---|---|---|---|
| Vitamin A (retinol) | 800 mcg (2,664 IU) | 1,500 mcg (5,000 IU) | 900 mcg (3,000 IU) |
| Vitamin B1 (thiamin) | 1.1 mg | 1.5 mg | 1.2 mg |
| Vitamin B2 (riboflavin) | 1.4 mg | 1.7 mg | 1.3 mg |
| Vitamin B3 (niacin) | 16 mg | 20 mg | 16 mg |
| Vitamin B5 (pantothenate) | 6 mg | 10 mg | 5 mg |
| Vitamin B6 (pyridoxine) | 1.4 mg | 2 mg | 1.7 mg |
| Vitamin B12 (cobalamin) | 2.5 mcg | 6 mcg | 2.4 mcg |
| Folic acid (folate) | 200 mcg | 400 mcg | 400 mcg |
| Biotin | 50 mcg | 300 mcg | 30 mcg |
| Vitamin C (ascorbate) | 80 mg | 60 mg | 90 mg |
| Vitamin D (cholecalciferol) | 5 mcg (200 IU) | 10 mcg (400 IU) | 20 mg (800 IU) |
| Vitamin E (tocopherol) | 12 mg (18 IU) | 20 mg (30 IU) | 15 mg (22.5 IU) |
| Vitamin K | 75 mcg | 80 mcg | 120 mcg |
| Choline | not set | not set | 550 mg |
NRVs and DVs for minerals
| MINERAL | UK/EU NRV | OLD US DV | NEW US DV (adults and children 4+) |
|---|---|---|---|
| Calcium | 800 mg | 1,000 mg (1g) | 1,300 mg |
| Chloride | 800 mg | 3,400 mg | 2,300 mg |
| Chromium | 40 mcg | 120 mcg | 35 mcg |
| Copper | 1 mg | 2 mg | 900 mcg (0.9 mg) |
| Iodine | 150 mcg | 150 mcg | 150 mcg |
| Iron | 14 mg | 18 mg | 18 mg |
| Magnesium | 375 mg | 400 mg | 420 mg |
| Manganese | 2 mg | 2 mg | 2.3 mg |
| Molybdenum | Not set | 75 mcg | 45 mcg |
| Phosphorus | 700 mg | 1,000 mg | 1,250 mg |
| Potassium | 2000 mg | 3,500 mg | 4,700 mg |
| Selenium | 55 mcg | 70 mcg | 55 mcg |
| Zinc | 10 mg | 15 mg | 11 mg |
NB In the UK, some multivitamins may still feature an RDA (Recommended Daily Amount), but these will soon change to the newer NRV (Nutrient Reference Value) which are exactly the same for labelling purposes.
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