µg or IU: knowing how to convert
Labels state vitamin D in micrograms, often alongside the equivalent in international units: 1 µg = 40 IU, so 25 µg = 1,000 IU. The NRV is 5 µg (200 IU). That is the first thing to look for when reading a vitamin D product.
The forms of D3
Cholecalciferol (D3) comes as oily drops (often 1,000 IU per drop), capsules or softgels. It is sourced either from lanolin or from lichen for a vegan option. The product sheet states the source and the dose per serving.
Vitamin K2
K2 is mostly represented by the menaquinone MK-7 (produced by fermentation), which has a long plasma half-life and is sometimes supplied in standardised all-trans forms. MK-4 also exists and is used at higher doses.
Why combine D3 and K2
Many manufacturers combine D3 and K2 in a single serving: these are two fat-soluble vitamins with separate EU claims (D for calcium and bone structure, K for blood clotting and bone structure). The exact composition appears on the product sheet.
A regulatory point of caution
Vitamin K interacts with vitamin K antagonist anticoagulant treatments. Product sheets carry the contraindications supplied by the manufacturers; medical advice is essential for any patient concerned.
