Who is most at risk of vitamin D deficiency in the UK?

Since we make most of our vitamin D from sunlight (and the weather in the UK is less than predictable), living in some areas of Britain means your risk of vitamin D deficiency is greater than in others.

We’ve analysed over 130,000 blood test results from the last three years. Are you living in a high-risk area?

In this article we look at:

• How common is vitamin D deficiency in the UK?
• What’s the average vitamin D level in your area?
• Which areas in Britian has the highest vitamin D levels?
• Vitamin D deficiency in London
• Which UK regions have the lowest vitamin D levels?
• Vitamin D deficiency in Scotland
• What else influences vitamin D levels?

How common is vitamin D deficiency in the UK?
 

You never know what you’re going to get with British weather.

While 2025 saw record-breaking sunshine seasons in the UK, 2024 was a much cloudier affair [1]. And although counties like Dorset, Hampshire, and Sussex soak up around 2,000 hours of sunshine a year, some areas in Scotland get half as much. 

It’s estimated that 1 in 6 of Brits are deficient in vitamin D. And yet, nearly half of adults are unaware of vitamin D supplement recommendations, and more than half don’t take supplements or take them inconsistently [2].  

So, what’s the advice? 

• Everyone should consider taking a daily 10 microgram vitamin D supplement during autumn and winter.
• If you’re in a higher-risk group for vitamin D deficiency, you’re better off taking a supplement all year round [2]. 

Vitamin D is so important for our health that we’ve created a whole collection of vitamin D articles for more information, with blogs about vitamin D supplements, why we need vitamin D, and which age groups are more at risk of vitamin D deficiency.

What’s the average vitamin D levels in your area?
 

We analysed the vitamin D levels of 131,104 Medichecks customer’s results, over a three year period, according to where they live in the UK.

The map below shows the regions of the UK, and their associated average vitamin D level. You may notice areas further south have higher levels, while areas up north have a lower average level.

UK regions with highest average vitamin D levels
 

The region with the highest average vitamin D levels was the sunny South West of England with an average level of 77 nmol/L. Closely following is the South East, East Midlands, and North West with 76 nmol/L as their average levels.

This is within the optimal range for vitamin D, where you will notice benefits such as enhanced immune function and mood.

Why does the South of England have higher vitamin D levels? There’s a number of reasons.

These areas:

• Get more annual sunshine 
• Have a high number of outdoor jobs and leisure pursuits 
• Have an active older population who may spend time outdoors 

Meanwhile areas further north such as the North West are likely following government and NHS guidelines, and supplementing with vitamin D.

You can read more about the difference between normal and optimal vitamin D levels in our blog.

Vitamin D deficiency in London
 

Nestled in between the South East and East of England is London. London has often shown up as a bit of an anomaly in our vitamin D analyses.

Since it’s so far south you’d expect London’s average vitamin D levels to be the same as its neighbouring regions.

But vitamin D levels in London are often a bit lower than its surrounding areas.

In this case, their average level is 75 nmol/L. So, what’s going on here?

UK regions with lowest average vitamin D levels
 

Scotland, the West Midlands, and Northern Ireland are in a tie for the lowest average vitamin D levels in the UK, at 73 nmol/L. This is slightly below the optimal level of vitamin D of 75 nmol/L.

People from these areas in the UK are at higher risk of vitamin D deficiency as there is less sunlight, longer winters, and the higher longitude means the UVB rays are less strong.

Vitamin D deficiency in Scotland
 

In Scotland, the higher longitude and cooler climate mean deficiency is more likely – even in summer you may be more likely to cover up your skin because of the lower temperature.

While the rest of UK are recommended to supplement vitamin D from October to March, Scotland’s advice is slightly different. The sun stops being strong enough for us to make vitamin D in September in Scotland, and this lasts until April.

Everyone in Scotland should take a vitamin D supplement containing 10 micrograms (400 IU) during these months and may do well to consider taking vitamin D in the summer too [2].

If you live in Scotland and are pregnant, breastfeeding, or a child under the age of three years old, you can ask your midwife and health visitor for information on free vitamin D supplements.

What else influences vitamin D levels?
 

As well as the weather, many other factors can affect your vitamin D levels. 

Factors affecting vitamin D levels include: 

• Age — the likelihood of vitamin D deficiency may increase with age depending on activity levels and time spent outdoors. The skin generally becomes less efficient at creating vitamin D from sunlight. Frail individuals are particularly at risk as they may spend less time outdoors [3].
• Gender — you’re more likely to have low vitamin D levels if you’re female. Some of this may be explained by the increased risk during pregnancy and breastfeeding [4].
• Skin colour — people with darker skin, such as people of African or South Asian descent, produce vitamin D more slowly when exposed to sunlight, due to higher melanin concentrations. A 2016 health report showed that average vitamin D levels were higher in white adults (45.8 nmol/L) compared to Asian (20.5 nmol/L) and black (27.7 nmol/L) adults [2,5].
• Obesity — vitamin D levels tend to be lower in people who are obese [5,6].
• Smoking — smoking is associated with lower vitamin D levels and it is unclear why [6,7]. Harmful chemicals in cigarette smoke may affect enzyme activity and the production of vitamin D [8].
• Time spent outdoors — people who are housebound or spend little time outdoors are more likely to be deficient in vitamin D (3). Around two in five adults in institutions (e.g. care homes) are vitamin D deficient [5].
• Shift work — shift workers and indoor workers are consistently reported as the occupational group most likely to have lower vitamin D levels as they expose themselves less frequently to direct sunlight [9].
• Chronic disease or malabsorption disorders — conditions like chronic kidney disease and Crohn’s disease are risk factors for low vitamin D due to malabsorption. [10,11]. 
• Medications — some drugs, such as steroids and anti-epilepsy medication, are likely to lower vitamin D levels [12].
• Clothing — wearing clothing that covers most of the skin when outside will prevent the body from producing as much vitamin D [2].

Can you get vitamin D through a window?

The sun emits UVA, UVB, and UVC rays. UVC rays are the most damaging, but they are filtered by the atmosphere and don’t reach the earth’s surface. 

UVB rays are what trigger the body to produce vitamin D, but most glass windows block this wavelength. On the other hand, most UVA rays will travel through ordinary glass, which means it’s still possible to burn through a window, but it’ll take longer than being in direct sunlight. 

So, if you’re planning to boost your vitamin D levels by working next to a sunny window, it’s not going to work. You’re best off taking a ten-minute break outdoors.  

Enjoying the sun safely

Sun exposure is the main source of vitamin D, but excessive sun exposure is the main cause of skin cancer, including melanoma, the fastest-rising type of cancer in the UK. Unsurprisingly, the risk of melanoma is greatest in the South and South West, where there is more sunshine. 

Enjoying the sun safely, whilst taking care not to burn, means you can get your hit of vitamin D whilst keeping your risk of skin cancer low.

References 

1. Double record breaker: Spring 2025 is warmest and sunniest on UK record. In: Met Office [Internet]. [cited 25 Nov 2025]. 
2. Vitamin D. In: NHS inform [Internet]. [cited 28 Nov 2025]. Available: https://www.nhsinform.scot/healthy-living/food-and-nutrition/eating-well/vitamin-d/
3. Gallagher JC. Vitamin D and Aging. Endocrinol Metab Clin North Am. 2013 Jun;42(2):319–32.
4. Muscogiuri G, Barrea L, Somma CD, Laudisio D, Salzano C, Pugliese G, et al. Sex Differences of Vitamin D Status across BMI Classes: An Observational Prospective Cohort Study. Nutrients. 2019 Dec;11(12):3034.
5. SACN vitamin D and health report [Internet]. GOV.UK. [cited 2025 Dec 21]. Available from: https://www.gov.uk/government/publications/sacn-vitamin-d-and-health-report
6. Tønnesen R, Hovind PH, Jensen LT, Schwarz P. Determinants of vitamin D status in young adults: influence of lifestyle, sociodemographic and anthropometric factors. BMC Public Health. 2016 May 11;16(1):385.
7. Lange NE, Sparrow D, Vokonas P, Litonjua AA. Vitamin D Deficiency, Smoking, and Lung Function in the Normative Aging Study. Am J Respir Crit Care Med. 2012 Oct 1;186(7):616–21.
8. Kassi EN, Stavropoulos S, Kokkoris P, Galanos A, Moutsatsou P, Dimas C, et al. Smoking is a significant determinant of low serum vitamin D in young and middle-aged healthy males. Hormones (Athens). 2015 Jun;14(2):245–50.
9. Coppeta L, Papa F, Magrini A. Are Shiftwork and Indoor Work Related to D3 Vitamin Deficiency? A Systematic Review of Current Evidences. J Environ Public Health. 2018 Sep 10;2018:8468742.
10. Williams S, Malatesta K, Norris K. Vitamin D and Chronic Kidney Disease. Ethn Dis. 2009;19(4 Suppl 5):S5-8–11.
11. Ham M, Longhi MS, Lahiff C, Cheifetz A, Robson S, Moss AC. Vitamin D Levels in Adults with Crohn’s Disease Are Responsive to Disease Activity and Treatment. Inflamm Bowel Dis. 2014 May;20(5):856–60.
12. Gröber U, Kisters K. Influence of drugs on vitamin D and calcium metabolism. Dermatoendocrinol. 2012 Apr 1;4(2):158–66.