Strong evidence · Vitamins & minerals
Vitamin D3
Preventing a deficiency in the winter months
Strong evidence
Multiple good studies and reviews point the same way.
In Belgium the sun is too low from October to March to make enough vitamin D. The Superior Health Council therefore recommends adults a supplement of 10 micrograms (400 IU) per day in the winter months. Higher doses often seen in shops (800–2000 IU or more) are not needed for the official advice; have your level measured if you're unsure.
- Dosage
- 400 IU (10 µg) per day in winter (advice of the Superior Health Council)
- Timing
- With a meal
- Approx. price
- €2–6 per month
Watch out
Fat-soluble, so it can accumulate: the EFSA upper limit for adults is 100 micrograms (4000 IU) per day. According to the Superior Health Council older people take it all year round, and teenagers and pregnant women have their own advice. If in doubt, have your level measured.
Frequently asked questions about supplements
How much Vitamin D3 per day?
400 IU (10 µg) per day in winter (advice of the Superior Health Council)
When should you take Vitamin D3?
With a meal
Does Vitamin D3 really work?
Strong evidence. Multiple good studies and reviews point the same way.
What does Vitamin D3 cost?
€2–6 per month
Basics first, then the tub
Supplements are called supplements because they add to something. Sleep, a protein intake that hits your protein calculator , a programme where you lift progressively heavier and enough food together do a hundred times more than the best-researched item on this list. Once those are in place, creatine, caffeine and vitamin D in winter are the three you can spend money on with a clear conscience — for less than ten euros a month combined.
Sources
- Hoge Gezondheidsraad (België): advies vitamine D voor volwassenen, 10 µg per dag in de wintermaanden. (official advice)
- EFSA (2012). Scientific opinion on the tolerable upper intake level of vitamin D. EFSA Journal 10(7):2813. (regulatory opinion)
More supplements in this category
Last updated: October 2026
This page summarises scientific research and is not medical advice. If you take medication, are pregnant or have a liver, kidney or thyroid condition, discuss supplements with your doctor or pharmacist — even the innocent-looking ones.
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