16 November 2020

As the days get darker the warm summer sun may feel like a long time ago. As well as enjoying the sunshine we also get some clear health benefits from time in the sun.

We are starting to hear more about the importance of vitamin D for protecting our health during the winter.

The sunshine vitamin

Vitamin D is actually a hormone and we make it when our skin is exposed to the sun. Since we don’t get much sun in the Northern Hemisphere during winter we are only able to make Vitamin D during the summer months (April-September).

This is because only when the sun is directly overhead is the radiation strong enough to trigger the production of vitamin D.  Any autumn or early spring sunshine doesn’t give the same results because the sun is lower in the sky.

Our levels decrease throughout the winter as we get further away from the summer months. Around 30–40% of the UK population are below the recommended concentration in winter (Jan-March) each year.

What does vitamin D do?

We all need vitamin D for strong bones and teeth, because it regulates the amount of calcium in our body. It’s an important mineral for children’s growing bones.

Vitamin D also helps to modulate our immune system health, and can help us ward off infections. 

Vitamin D in the diet

Unfortunately there are no natural foods which provide a good source of vitamin D. Some oily fish, liver and egg yolks can provide a small amount.

It’s thought regular intake of these foods would cover a maximum 10% of our vitamin D requirements.  

Mushrooms grown under a UV light may contain traces of Vitamin D.

The NHS recommend we all consider taking a supplement during the winter.


What to look for in a supplement

Vitamin D normally comes in two forms. There is D3 (which will be Cholecalciferol in the ingredients list) or D2 (Ergocalciferol). Some studies show that D3 is better absorbed than D2.

D3 is normally produced from lanolin so wouldn’t be suitable for vegans, but is ok for vegetarians. D2 is produced from plant sources.

Fortified foods like non-dairy milk normally contain D2, and eating cereals and milks with extra vitamin D can help boost your levels, but shouldn’t be relied on for the levels you need during the winter.

If you rely on fortified foods to get your Vitamin D, you may not actually absorb the amount you think you’re taking.

More isn’t always better

Vitamin D is a fat soluble vitamin so it gets stored in your body (whereas vitamin C and B vitamins are water soluble so flush through us each day).

We shouldn’t take high doses of vitamin D unless a medical professional has advised you need this.

  • Children aged 1 to 10 years should not have more than 50 micrograms (2,000 IU) a day.
  • Adults should not take more than (100 micrograms (4,000 IU) a day.

Home testing kits are available if you are interested in checking your levels before supplementing, and if you have any medical questions or concerns about Vitamin D, please contact your GP or local pharmacist.

Anna Mapson, Registered Nutritionist (BANT)