Vitamin D in Winter How to Keep Your Levels Healthy Naturally
Shorter days, colder weather and weaker sunlight can all make vitamin D harder to maintain in the UK. During autumn and winter, many people spend more time indoors, cover more skin when they go outside and receive less of the UVB light needed for vitamin D production in the skin.
Vitamin D is often called the sunshine vitamin, but sunlight is only one part of the picture. Food, supplements, personal risk factors and testing can all play a role in maintaining healthy vitamin D levels through the colder months.
The aim is not to panic about deficiency or chase high doses. It is to understand what vitamin D does, why winter changes your needs, and how to support your levels in a safe, realistic and evidence-informed way.
Why vitamin D matters for everyday wellbeing
Vitamin D is a fat-soluble vitamin. That means the body absorbs it alongside fat and can store some of it in body tissues. It supports several established functions, including:
Helping the body absorb calcium and phosphate
Supporting normal bones and teeth
Contributing to normal muscle function
Supporting the normal functioning of the immune system
These roles are well recognised in UK nutrition guidance. Vitamin D is especially relevant for bone health, because calcium cannot do its job properly without enough vitamin D.
When vitamin D levels become very low for a prolonged period, adults can develop osteomalacia. This is a condition where bones soften, which may lead to bone pain and muscle weakness. Low levels may also be picked up through a blood test before clear symptoms appear.
Vitamin D is also widely researched in relation to immune regulation and other areas of health. This research is interesting, but it should be understood carefully. Low vitamin D status has been linked with several health conditions, yet that does not mean supplements prevent or treat those conditions. For most people, the goal is simple: meet the body’s nutritional need and avoid deficiency.
Why vitamin D levels can drop in the British winter
The body makes vitamin D when skin is exposed to ultraviolet B, known as UVB, from sunlight. In the UK, from around October to early March, the sun is usually too low in the sky for the skin to make enough vitamin D.
This is one of the main reasons UK guidance recommends a daily vitamin D supplement during autumn and winter for most adults.
Several everyday factors can reduce vitamin D production or increase the chance of low levels:
Spending much of the day indoors
Wearing clothing that covers most of the skin
Using high-factor sunscreen during sunny months
Having darker skin, which naturally reduces UVB penetration
Living in northern parts of the UK
Working night shifts or long indoor hours
Having limited mobility or rarely going outside
Following a diet with few vitamin D-rich foods
None of these factors means someone will definitely be deficient. They simply make it more sensible to pay attention to intake, particularly during winter.
This is why Vitamin D in Winter deserves a practical plan rather than guesswork. Sunlight becomes less reliable, so food and supplements often need to do more of the work.
What deficiency can feel like and when to test
Vitamin D deficiency does not always cause obvious symptoms. Some people feel well even when their levels are low. When symptoms do occur, they can be vague and may overlap with many other causes.
Possible vitamin D deficiency symptoms can include:
Tiredness that feels out of proportion
Aching bones or muscles
Muscle weakness
Low mood
More frequent aches and pains
These symptoms can have many explanations, so it is best not to self-diagnose based on symptoms alone.
A blood test can measure vitamin D status. In the UK, this is often called a 25-hydroxyvitamin D test. A GP may recommend testing if there are symptoms, relevant medical conditions, certain medications, a history of deficiency, or higher risk of low levels.
Private vitamin D testing is also available in the UK, but results should still be interpreted sensibly. More is not always better, and very high intake can be harmful. If results are low, a healthcare professional can advise on the right dose, duration and whether follow-up testing is needed.
How to increase vitamin D naturally through food
Food alone is unlikely to provide all the vitamin D most adults need in winter, but it can still make a useful contribution. A food-first approach also supports wider nutrition, including protein, omega-3 fats, minerals and other vitamins.
Good dietary sources include oily fish, eggs, fortified foods and some mushrooms. Fortified foods are especially helpful for people who do not eat fish or animal products.
Food source | How it can help |
Salmon, sardines, trout and mackerel | Oily fish naturally contain vitamin D and also provide omega-3 fats |
Egg yolks | A simple everyday source, especially when eaten as part of a balanced meal |
Fortified milk alternatives | Many soya, oat and almond drinks contain added vitamin D, but check the label |
Fortified breakfast cereals | Some cereals contribute vitamin D, though sugar and fibre content vary |
Fortified spreads | Often contain added vitamin D and can be easy to include in meals |
UV-exposed mushrooms | Some mushrooms contain vitamin D2 when exposed to ultraviolet light |
For a practical winter plate, combine vitamin D-rich foods with healthy fats and protein. For example:
Scrambled eggs with mushrooms and wholegrain toast
Sardines on rye bread with salad
Salmon with roasted vegetables and yoghurt dressing
Fortified porridge made with a vitamin D-enriched plant drink
Omelette with spinach, mushrooms and a side of avocado
The phrase “natural” can mean different things. When it comes to how to increase vitamin D naturally, it helps to think in layers: safe daylight exposure when available, vitamin D-rich foods, and a supplement when dietary intake and winter sunlight are not enough.
Where supplements fit in safely
For many adults in the UK, supplements are the most reliable way to meet winter vitamin D needs. Current UK guidance advises adults and children over four to consider taking 10 micrograms of vitamin D per day during autumn and winter.
Some people are advised to consider a daily supplement throughout the year, including those who have little or no sun exposure, wear clothing that covers most of the skin outdoors, or have darker skin.
Vitamin D supplements usually come as D2 or D3.
Vitamin D3
This is the form made in human skin. Many D3 supplements come from lanolin, which is derived from sheep’s wool. Vegan D3 made from lichen is also available.
Vitamin D2
This is usually plant or fungal derived. It can still raise vitamin D levels, although D3 is often used because it tends to be more effective at maintaining levels.
For most adults, the standard daily amount recommended in the UK is enough unless a healthcare professional advises otherwise. High-dose supplements should not be taken long term without guidance. Too much vitamin D can lead to excess calcium in the blood, which may cause health problems.
When choosing a supplement, check:
The dose in micrograms, often shown as µg
Whether it is D2 or D3
Whether it suits dietary needs, such as vegan or halal preferences
Whether it is a daily supplement or a higher-dose product
Whether it interacts with any medicines or health conditions
A common UK label may show both micrograms and international units. As a guide, 10 micrograms equals 400 IU. Avoid combining several supplements that all contain vitamin D unless you have checked the total daily amount.
Building a simple winter routine
Supporting vitamin D levels works best when it becomes part of normal life. Small, consistent habits are usually more useful than occasional bursts of effort.
A balanced winter routine might include the following:
Take a daily supplement with a meal
Vitamin D is fat-soluble, so taking it with food that contains some fat may support absorption. Breakfast, lunch or dinner can all work. The best time is the time you will remember.
Include vitamin D foods several times a week
Oily fish once or twice a week can be a helpful habit for those who eat it. Eggs, fortified foods and mushrooms can fill gaps on other days.
Get outside for daylight when possible
Winter sunlight in the UK may not provide much vitamin D, but outdoor daylight still supports routine, mood and general wellbeing. A lunchtime walk can be worthwhile even when vitamin D production is limited.
Think about personal risk
A person who works outdoors in summer and eats oily fish may have different needs from someone who works indoors, rarely sees midday daylight and avoids animal products. Personal context matters.
Seek advice when health factors are involved
People with kidney disease, sarcoidosis, parathyroid conditions, malabsorption conditions, a history of kidney stones, or those taking certain medicines should ask a health professional before using supplements, especially higher doses.
A balanced approach works best
Vitamin D is important, but it is only one part of nutritional wellbeing. A winter health routine should also include enough protein, fibre-rich carbohydrates, colourful fruit and vegetables, healthy fats, regular movement and good sleep habits.
It is also worth keeping perspective. Many UK adults need extra vitamin D during winter because of the climate, not because they have done anything wrong. The aim is to meet a normal seasonal need in a safe and steady way.
For most adults, a sensible plan looks like this:
Follow UK guidance and consider 10 micrograms daily during autumn and winter
Eat vitamin D-rich foods where possible
Choose fortified foods if fish, eggs or dairy are not regular parts of the diet
Avoid high-dose supplements unless advised
Ask about testing if symptoms, medical history or risk factors suggest it may be useful
Winter makes vitamin D harder to maintain, but it also makes the solution clearer. A daily supplement, a few well-chosen foods and awareness of personal risk can go a long way towards supporting healthy levels naturally and safely.
Book a free 20-minute discovery call to explore how personalised support could fit into your wellbeing journey.
References
Cardwell, G., Bornman, J.F., James, A.P. and Black, L.J. (2018) ‘A review of mushrooms as a potential source of dietary vitamin D’, Nutrients, 10(10), 1498. Available at: https://doi.org/10.3390/nu10101498
Cashman, K.D. and O’Neill, C.M. (2024) ‘Strategic food vehicles for vitamin D fortification and effects on vitamin D status: A systematic review and meta-analysis of randomised controlled trials’, The Journal of Steroid Biochemistry and Molecular Biology, 238, 106448. Available at: https://doi.org/10.1016/j.jsbmb.2023.106448
Dawson-Hughes, B. et al. (2015) ‘Dietary fat increases vitamin D-3 absorption’, Journal of the Academy of Nutrition and Dietetics, 115(2), pp. 225–230. Available at: https://doi.org/10.1016/j.jand.2014.09.014
Department of Health and Social Care (2016) PHE publishes new advice on vitamin D. Available at: https://www.gov.uk/government/news/phe-publishes-new-advice-on-vitamin-d
Department of Health and Social Care (2023) Fortifying foods and drinks with vitamin D: summary. Available at: https://www.gov.uk/government/publications/fortifying-food-and-drink-with-vitamin-d-a-sacn-rapid-review/fortifying-foods-and-drinks-with-vitamin-d-summary
European Food Safety Authority (2012) Scientific Opinion on the Tolerable Upper Intake Level of Vitamin D. Available at: https://www.efsa.europa.eu/
Holick, M.F. (2007) ‘Vitamin D deficiency’, The New England Journal of Medicine, 357(3), pp. 266–281. Available at: https://doi.org/10.1056/NEJMra070553
Martineau, A.R. et al. (2017) ‘Vitamin D supplementation to prevent acute respiratory tract infections: systematic review and meta-analysis of individual participant data’, The BMJ, 356, i6583. Available at: https://doi.org/10.1136/bmj.i6583
National Health Service (n.d.) Vitamins and minerals: Vitamin D. Available at: https://www.nhs.uk/conditions/vitamins-and-minerals/vitamin-d/
National Institute for Health and Care Excellence (2014) Vitamin D: supplement use in specific population groups (PH56). Available at: https://www.nice.org.uk/guidance/ph56
National Institutes of Health, Office of Dietary Supplements (n.d.) Vitamin D: Fact Sheet for Health Professionals. Available at: https://ods.od.nih.gov/factsheets/VitaminD-HealthProfessional/
Office for Health Improvement and Disparities (2021) Vitamin D deficiency: migrant health guide. Available at: https://www.gov.uk/guidance/vitamin-d-deficiency-migrant-health-guide
Scientific Advisory Committee on Nutrition (2016) Vitamin D and Health. London: Public Health England. Available at: https://www.gov.uk/government/publications/sacn-vitamin-d-and-health-report
Scientific Advisory Committee on Nutrition (2024) Fortifying foods and drinks with vitamin D: a SACN rapid review. Available at: https://www.gov.uk/government/publications/fortifying-food-and-drink-with-vitamin-d-a-sacn-rapid-review
Tripkovic, L. et al. (2012) ‘Comparison of vitamin D2 and vitamin D3 supplementation in raising serum 25-hydroxyvitamin D status: a systematic review and meta-analysis’, The American Journal of Clinical Nutrition, 95(6), pp. 1357–1364. Available at: https://doi.org/10.3945/ajcn.111.031070
Webb, A.R., Kline, L. and Holick, M.F. (1988) ‘Influence of season and latitude on the cutaneous synthesis of vitamin D3: exposure to winter sunlight in Boston and Edmonton will not promote vitamin D3 synthesis in human skin’, The Journal of Clinical Endocrinology & Metabolism, 67(2), pp. 373–378. Available at: https://doi.org/10.1210/jcem-67-2-373
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