With winter fast approaching and the shorter days upon us, should we be more aware of the effects of less exposure to sunlight? For much of the year in the UK, most of us are able to get enough Vitamin D from sunlight.

But what about the winter months? Can you get enough Vitamin D from food alone or should we consider taking supplements?  

What is vitamin D?

Vitamin D is an important nutrient that helps to regulate the amounts of calcium and phosphate in our body. In turn this keeps our bones, teeth and muscles healthy. Without enough Vitamin D, people are at risk of soft bones, bone pain and eventually rickets (weak bones and bone deformities).

Vitamin D might also have a role to play in cardiovascular health – a deficiency in Vitamin D may be associated with an increased risk of heart disease and stroke. 

Recent studies also suggest that getting enough Vitamin D may reduce the severity of asthma attacks (alongside existing asthma treatment). If you suffer from asthma, speak to your GP for more information.

Where do we get Vitamin D from?

We can get Vitamin D from three sources:

1. Sunlight – this is where 90% of our Vitamin D comes from. Vitamin D is made in our bodies under our skin when it reacts with UVB rays (sunlight). This is why it is sometimes referred to as the ‘Sunshine Vitamin’.

2. Food – there are a few sources of Vitamin D in our food but it is difficult to get enough Vitamin D from food alone:

• Oily fish (such as salmon, mackerel, sardines and herring)
• Red meat
• Egg yolks
• Fortified foods (some fat spreads and breakfast cereals)

3. Vitamin D supplements

How much Vitamin D do we need?

Most adults need 10 micrograms of Vitamin D every day (this might be written as 10mcg or 10µg).

Sometimes Vitamin D is presented in ‘international units’ (IU).

10mcg of Vitamin D is equal to 400IU.

Do I need to take a Vitamin D supplement?

As we now know, most of our Vitamin D comes from sunlight and it is difficult to get enough Vitamin D just from food.

Most adults should be able to get enough Vitamin D from sunlight from March to September, but outside of these months (October to early March) we don’t get enough Vitamin D from sunlight in the UK. This is because winter sunlight doesn’t contain enough UVB rays (the type that your body needs to make Vitamin D).

Scottish Government recommends that everyone (all adults and children age 5 and above) should consider taking a supplement of 10mcg Vitamin D daily, especially during the winter months (October to March). This is based on research by the SACN (Scientific Advisory Committee on Nutrition) published in July 2016.

Other groups of people who are at high risk of developing Vitamin D deficiency, should consider taking a supplement all year round, after discussing this with their GP. These are groups of people who have little or no exposure to sunlight, for example:

• People in care homes or those who rarely get outdoors (UVB rays can’t get through glass, so sitting indoors by a sunny window is not enough)
• People who cover up their skin when they are outdoors
• People with darker skin might not get as much Vitamin D from sunlight, even in the summer months (e.g. people from African, African-Caribbean or South Asian backgrounds)

If you choose to take a Vitamin D supplement, you should not take more than 100mcg per day as this could be harmful. If you take other supplements, make sure that you aren’t getting extra doses of Vitamin D (for example, in a multivitamin or cod liver oil).

Always seek medical advice before starting a new supplement or medication. For advice about children and pregnant or breastfeeding mothers, please speak to your GP.