Vitamin D
Vitamin D is a vitamin the body needs for bones, muscles and the immune system, and it is made in the skin when exposed to sunlight.
Vitamin D is a vitamin the body needs for bones, muscles and the immune system, and it is made in the skin when exposed to sunlight. It helps the body take up calcium from food. The test measures 25-hydroxy vitamin D, the form that reflects the body’s supply from both sun, food and supplements. Retesting shows how it changes over time.
In Sweden the level follows the seasons: it is usually lowest in late winter and highest in late summer. Little time outdoors, darker skin, covering clothing, sun cream and age reduce how much the skin makes. Supplements and fatty fish raise it.
Foods that help
Fatty fish such as salmon, mackerel and herring, eggs, and fortified dairy and plant drinks. Time outdoors in daylight from spring to autumn.
Foods to limit
Taking several vitamin D supplements at once or high doses over a long time without a clear need.
Track it through the year
One value is a snapshot. Following it up shows whether what you changed is working.
Related markers
Educational information only — not a diagnosis. Every result is checked against safe limits, and anything critical is escalated for follow-up.
See all 84 markers →