How to know if you’re vitamin D deficient and what to do about it

We asked the experts about the common deficiency and how to treat it

From taking supplements to spending time in the sun, here’s how to ensure you’re getting enough vitamin D (The Independent/ iStock )

I’m going to start with some housekeeping. The first thing to say about vitamin D is it’s actually not a vitamin at all (yes, really) – you can sometimes get it through your diet, but the idea is for your body to manufacture it by itself (in response to sunlight), meaning it’s considered a type of hormone by those in the know. So, there’s some trivia for you.

The next thing to say is, if you live in the UK, you’re probably not getting enough sunlight (especially during the winter months) to produce enough vitamin D, and will likely need to supplement your intake along the way, as you might with omegas or probiotics.

Keen to know more? Here, we asked the experts to weigh in and explain what causes vitamin D deficiency, the important signs to look out for, and the dangers involved, as well as what to do if you think you might have a vitamin D deficiency.

What causes vitamin D deficiency?

As sunlight is our main natural source of vitamin D, short winter days or less-sunny climes can have an impact when it comes to getting enough vitamin D. Maz Packham, nutritionist at Nourishful Nutrition, explains: “We synthesise vitamin D in the skin in response to UV light – more specifically to UVB – so, it’s not surprising many of us in the UK are deficient or have insufficient levels due to seasonal factors.”

Nutritional therapist Eve Kalinik agrees, adding that even those living in “sunnier climes might be deficient, if using SPF and not exposing skin at all. But, of course, there has to be a balance here,” it’s still important to protect your skin from getting burnt from too much sun, after all.

While it is possible to source some vitamin D through diet, it will be a small amount, with Hannah Alderson, registered BANT nutritionist and hormone specialist, advising: “Yes, we can get a little from food – such as mushrooms, oily fish, dairy, and eggs – but that’s not really going to cut it.”

There are a few further things to consider when looking at the causes of vitamin D deficiency. According to Kalinik: “Some people suffer from a lack of absorption as a result of poor gut health and/or conditions such as Crohn’s and coeliac disease.” She adds that “Some groups are just vulnerable to vitamin D deficiency, like those of a certain age, or those with dark-coloured skin.”

What are the signs of vitamin D deficiency?

This is where things get really tricky because this deficiency can show up in many ways. Kalinik says, first and foremost, an unexplained “susceptibility to infections and viruses” might be a sign, given that vitamin D is a crucial component of robust immune function. Signs of deficiency may also present as “bone pain or muscle weakness (since vitamin D helps with the balance of calcium in the body) or even low mood and fatigue, which can often be associated with SAD (seasonal affective disorder).”

Alderson says there’s a hormonal element to consider, too: “Vitamin D plays a role in reproduction and glucose balance, and therefore PCOS (polycystic ovary syndrome), with the prevalence of vitamin D deficiency in women with PCOS being around 67-85 per cent.” So, it’s worth paying attention to possible hormonal imbalances and all their attendant symptoms, too.

What should I do if I’m vitamin D deficient?

The first thing you could do is try an at-home blood test – they’re readily available and give a good indication of your current status. Packham adds that you can try to increase your levels of vitamin D by upping your exposure to direct sunlight: “Aim for 25-30 minutes in the midday sun, as levels are more abundant when the sun is highest in the sky, making the vitamin D synthesising process more efficient.” The experts all advise making sure oily fish and egg yolks are a part of the diet – but they concede that even if you did all of the above, supplementing is, in all likelihood, going to be the way to go, especially during the winter months in the UK.

We’ve put together a handy guide to the best vitamin D supplements to try. If softgels are preferred, Myvitamins vitamin D3 softgels are a great affordable option, similarly, the Nutrition Geeks vitamin D3 contains enough capsules for a whole year.

For more expert advice, take a look at our guide to the best menopause supplements