Best Vitamin D3 Supplements UK (2026)

Should you take vitamin D?

If you live in the UK — almost certainly yes. The UK's latitude means that UVB sunlight is insufficient to stimulate vitamin D production in skin from October to April. The NHS officially recommends all adults consider a supplement during autumn and winter. For many people (those who work indoors, have darker skin, or are housebound), year-round supplementation makes sense.

D3 vs D2: which should you buy?

Always choose vitamin D3 (cholecalciferol) over D2 (ergocalciferol). D3 is the form your skin naturally produces and is significantly more effective at raising and maintaining blood 25(OH)D levels. D2 is plant-derived and may suit strict vegans, but D3 from lichen is also available as a vegan option.

How much vitamin D do you need?

• NHS minimum recommendation: 400 IU (10mcg) daily

• Widely used maintenance dose: 1000–2000 IU (25–50mcg)

• For correcting confirmed deficiency: 3000–4000 IU under medical guidance

• Upper safe limit for adults: 4000 IU (100mcg) daily

The ideal dose depends on your baseline levels. If you've never had a blood test, start with 1000 IU daily and consider testing your 25(OH)D levels after 3 months.

D3 + K2: should you bother?

Combined D3+K2 supplements have become popular for good reason. Vitamin D increases calcium absorption, and K2 (as MK-7) directs that calcium to bones rather than arteries. For anyone supplementing long-term at higher doses, adding K2 is a sensible safeguard.

Our top pick: Simply Supplements Vitamin D3 1000 IU

At under £10 for 365 capsules, Simply Supplements Vitamin D3 is remarkable value. A full year's supply for the cost of two coffees. The D3 form is correct, the dose is right, and the track record of the brand is solid. Hard to fault for most people.

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