Nutrientsng/ml
25(OH) vitamin D
Optimal
30–50 ng/ml (75–125 nmol/l)
Why
Below 20 bone, muscle and immunity suffer; above 60 no extra benefit and kidney-stone risk rises.
How often
Yearly, in winter (the low point).
What moves it
D3 1,000–2,000 IU, summer sun, oily fish.
Last reviewed: 6 September 2026
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