Vitamin D is less a vitamin than a hormone the body makes in the skin from sunlight — and one of the most common shortfalls in a country where we increasingly work and live indoors. Our vitamin D collection brings together D3 in capsules, drops and combined D3 + K2 formulas, in doses to suit everyday maintenance through to practitioner-guided correction.

How vitamin D works — a hormone with receptors everywhere

When UVB light hits the skin, it begins making vitamin D, which the liver then converts to the storage form (25-hydroxyvitamin D, the one measured in blood tests) and the kidney activates into its hormonal form. What makes it so far-reaching is that vitamin D receptors are found on cells throughout the body — not just bone, but immune cells, muscle and more — which is why it influences calcium absorption, immune regulation and muscle function. Most supplements use D3 (cholecalciferol), the same form the skin makes and the more effective at raising blood levels than D2.

What to look for — and why K2 often joins it

Vitamin D's main job in bone is to increase calcium absorption from the gut. Vitamin K2 then directs that calcium into bone and away from arteries, which is why D3 and K2 are frequently paired. Because vitamin D is fat-soluble, it is best absorbed with a meal containing some fat, and oil-based drops or capsules suit that well. Dosing ranges widely — from low daily maintenance to higher practitioner-directed doses for those who are deficient — so a blood test is the most reliable guide.

Who may benefit

People with limited sun exposure, those who cover up or have darker skin, older adults (whose skin makes less), shift workers, and anyone whose blood test shows a low level commonly supplement vitamin D, particularly through the lower-light months.

Frequently asked questions

How much vitamin D should I take?
It depends on your current level, which is why a blood test helps. Maintenance doses are modest, while correcting a genuine deficiency may need more under guidance. More is not automatically better — vitamin D is fat-soluble and stored, so very high doses should be supervised.

Should I take vitamin D with K2?
Many people do. Vitamin D increases calcium absorption, and K2 helps deposit that calcium into bone rather than soft tissue, so the two are complementary — especially if you also supplement calcium.

D3 or D2 — which is better?
D3 (cholecalciferol) is the form your skin makes and is more effective at raising and maintaining blood levels, so it is the usual choice. D2 is plant-derived and sometimes used in vegan products.

Explore related ranges in our Immunity, Bone Health, Calcium and Magnesium collections.

Always read the label and follow the directions for use. High-dose vitamin D should be taken under professional guidance. If you are pregnant, taking medication or have a medical condition, talk to your health professional.