Vitamin D: why you’re short on it and how much to take
2026-06-27 · 5 min read
Vitamin D is called the “sunshine vitamin” because the body makes it when sunlight hits the skin. It matters for bones, immunity, muscles and mood, yet its deficiency is one of the most common.
Why you need it
Vitamin D helps absorb calcium and keep bones strong, and supports immunity, muscles and mood. A shortfall often shows up as fatigue and frequent colds.
Why deficiency is common
In winter there is little sun, people spend most of the day indoors, and covering clothing reduces production. So deficiency occurs even in sunny regions.
How much and which form
The D3 form is more effective than D2. A typical maintenance dose is 1000–2000 IU per day with a meal containing fat. The exact dose is best set from a 25(OH)D blood test.
FAQ
How do I know if I’m low on vitamin D?
For certain, with a 25(OH)D blood test. Indirect signs (fatigue, frequent colds) are nonspecific, so do not rely on them alone.
Do I need vitamin K2 with D3?
They are often combined: K2 helps direct calcium into bones. Many supplements come as D3+K2 together.
Related sections
This article is for information only and is not a substitute for professional advice. Supplements are not medicines.