Vitamin D is one of the few supplements that official health advice actually recommends for many people, and the reason comes down to a quirk of living this far north. We simply cannot make enough of it for part of the year.
Why Britain has a problem
Your skin makes vitamin D when sunlight hits it, but only when the sun is high enough in the sky. Across the UK, from roughly October to March, the sun never climbs high enough to do the job, no matter how long you stand outside. So through the darker half of the year, most people's levels quietly drift down.
Vitamin D matters for healthy bones, and there is growing interest in its wider role in the immune system. A shortage is common and often goes unnoticed.
What to do about it
The official advice for the UK is straightforward.
- Consider a daily ten microgram vitamin D supplement through autumn and winter
- Some groups should take it all year, including people who get little sun and those with darker skin
- A little summer sun on bare skin helps build stores, without burning
- A few foods help a bit, oily fish, eggs and fortified products
The sensible takeaway
This is one of the rare cases where a cheap supplement is genuinely worth it for a large part of the population, simply because our geography works against us for half the year. A small daily dose through the winter is a sensible, evidence-backed habit, and one of the few in the supplement aisle that earns its place.