Why Vitamin D still matters after a summer heatwave

After the summer we’ve just had, it might seem strange to talk about vitamin D. We’ve had sunshine, soaring temperatures and more than enough days when stepping outside felt like walking into an oven. Surely, after all that sunshine, our vitamin D levels must be topped up for the months ahead?

Unfortunately, it isn’t quite that simple.

Vitamin D is often called the “sunshine vitamin” because our bodies can make it when our skin is exposed to sunlight. But it’s not the heat itself that creates vitamin D — it’s exposure to UVB rays from the sun. And as we move into autumn and winter in the UK, the angle of the sun changes and there is much less UVB available for our skin to make sufficient vitamin D.

So, what happens after summer?

Our bodies can store vitamin D, which is one reason why getting some sensible sun exposure during the brighter months is helpful. However, those stores gradually decline over autumn and winter.

Even during a hot summer, there are many reasons why we may not produce as much vitamin D as we imagine. We may spend much of the hottest part of the day indoors, seek shade, wear clothing that covers our skin or apply sunscreen, all sensible measures when protecting our skin from excessive UV exposure.

And, of course, a heatwave doesn't necessarily mean that every day provides the right conditions for vitamin D production.

As the days shorten and we spend more time indoors, our opportunity to make vitamin D naturally becomes increasingly limited.

Why do we need vitamin D?

Vitamin D has several important roles in the body. It helps us absorb calcium and phosphorus, supporting the maintenance of normal bones and teeth. It also contributes to the normal function of our muscles and immune system.

This is particularly important as we head into the colder months, when we may naturally become less active and spend more time indoors.

Vitamin D isn't a magic solution to winter tiredness or every seasonal sniffle, but maintaining adequate levels is an important part of looking after our overall wellbeing.

Food can help — but may not be enough

There are some dietary sources of vitamin D, including oily fish, egg yolks and foods that have been fortified with vitamin D. However, it can be difficult to obtain enough through food alone.

This is why UK health guidance recommends that adults consider taking a daily vitamin D supplement during the autumn and winter months. The commonly recommended amount is 10 micrograms (400 IU) per day.

Some people may need different advice depending on their circumstances, so it’s always worth speaking to your GP or pharmacist if you are unsure.

Don't wait for the cold weather

Perhaps the most important thing to remember is that vitamin D isn't something we suddenly need when winter arrives. Our levels can gradually fall as summer comes to an end.

So, while we may still be enjoying some warm days it’s a good time to start thinking ahead.

The sunshine may have given us some vitamin D over the summer, but it doesn't provide a guarantee that our levels will remain sufficient throughout the darker months.

As we transition from long, light days into autumn, think of vitamin D as one small piece of the bigger wellbeing picture alongside nourishing food, movement, good-quality sleep, time outdoors and plenty of opportunities to slow down.

Summer may have been exceptionally sunny, but our bodies still need a little preparation for the season ahead.