Vitamin D3+K2 — Why Together and How to Dose Year-Round

The Polish sun problem

Poland is located at latitude 49–54°N. Vitamin D3 synthesis in skin is only possible when UV-B angle > 35°, which in Poland only occurs from May to September, between 10am–3pm, on clear days with exposed skin.

Result: the vast majority of Poles have vitamin D deficiencies for 6–7 months per year.

Why the laboratory "norm" is too low

Most labs list 20 ng/mL as the lower limit. However:

• 20–30 ng/mL is insufficiency, not optimality
• Clinical studies define the optimal range as 40–60 ng/mL for full immune and bone function
• Levels >100 ng/mL can be toxic (hence K2 as protection)

Vitamin D3 dosing

1. Get a 25(OH)D test before supplementing
2. If < 20 ng/mL: start with 4000–5000 IU D3 for 3 months, then retest
3. If 20–40 ng/mL: 2000–3000 IU D3 daily
4. If 40–60 ng/mL: 1000–2000 IU for maintenance, mainly autumn-winter
5. Always: with fat + K2 MK-7 minimum 100 µg