If you live in the Netherlands, Belgium or Germany and your energy dips every winter, you are far from alone. Vitamin D deficiency is one of the most common nutritional gaps I see, and in the grey, cloudy climate of Northern Europe it is almost the rule rather than the exception. Many people spend months waiting for bloodwork to explain their tiredness, low mood or achy muscles, only to discover their vitamin D level has quietly dropped. It is reassuring, in a way, because it is one of the most straightforward things to identify and address.
As a dietitian, I want to be honest with you from the start. Correcting vitamin D deficiency is not something food alone usually manages, and nutrition does not cure any condition on its own. What I can offer you here is a clear, evidence-aligned understanding of why deficiency happens, how food and sunlight help, and why testing and doctor-guided supplementation matter so much. Everything below is general education and works alongside your medical care, never in place of it.
For deeper context, see: 5 Nutrition Changes That Actually Help with PCOS (From a Dietitian Who Gets It).
Why Vitamin D Deficiency Is So Common in Northern Europe
Vitamin D is unusual among nutrients because your body can make it in your skin when exposed to strong ultraviolet B sunlight. The catch is that this only works well when the sun is high enough in the sky, which in the Netherlands, Belgium and Germany happens for only part of the year. From roughly October to March, the sun sits too low for your skin to produce meaningful amounts, no matter how long you stand outside. Add frequent cloud cover, short days and indoor lifestyles, and it is easy to see why so many people run low.
Several groups are at even higher risk, and it is worth knowing if you fall into one:
- People with darker skin, whose higher melanin reduces vitamin D production from the same sun exposure
- Those who cover most of their skin for cultural or religious reasons
- Older adults, whose skin makes vitamin D less efficiently
- People who spend most of daylight hours indoors
- Those who are pregnant or breastfeeding
- People with certain gut, liver or kidney conditions that affect absorption
None of these is a fault. They are simply reasons your body may not be getting what it needs from sunlight alone, which makes testing all the more useful.
Symptoms Worth Paying Attention To
Vitamin D deficiency is often quiet, and mild cases may cause no obvious symptoms at all, which is exactly why it is easy to miss. When symptoms do appear, they tend to be vague and easy to attribute to other things:
- Persistent tiredness and low energy
- Aching muscles or muscle weakness
- Bone or joint discomfort, particularly in the back or hips
- Low mood, especially through the darker months
- Getting sick more often than usual
- Hair thinning in some cases
Because these overlap with so many other conditions, symptoms alone should never be used to diagnose or self-treat. They are simply a reason to ask your doctor for a blood test rather than to start guessing at supplements.
Vitamin D Food Sources That Genuinely Help
Food is a real part of the picture, even if it is rarely enough on its own. Building these into your week supports your overall status and provides a steady, gentle contribution.
The strongest natural food sources are:
- Oily fish such as salmon, mackerel, sardines, herring and trout, which are the richest everyday sources
- Egg yolks, particularly from hens raised outdoors
- Mushrooms, especially those exposed to ultraviolet light, which raises their vitamin D content
- Fortified foods common across Europe: many margarines and spreads, some plant-based and dairy milks, and certain yoghurts and cereals
- Cod liver oil, a traditional and concentrated source, though best discussed with your doctor because it is also very high in vitamin A
A practical way to think about it: aim for oily fish a couple of times a week, keep eggs in your routine, choose fortified products where they fit, and enjoy mushrooms often. These habits build a helpful baseline, and they bring many other nutrients along with them.
Sunlight, and Why Food Alone Rarely Fixes a Deficiency
I am often asked whether someone can simply "eat their way out" of a vitamin D deficiency. The honest answer is that this is very difficult. Even a diet rich in oily fish typically provides only a fraction of what a deficient person needs to rebuild their levels, and it would be unrealistic to eat enough fish every single day to close a real gap.
Sunlight helps during the lighter months. When the sun is high, short, regular exposure of the face, arms and hands without burning supports natural production, but this is not a reliable year-round strategy in Northern Europe and must always be balanced against skin cancer risk. I never advise anyone to seek strong sun or use sunbeds for vitamin D. This is precisely why, for a genuine deficiency, food and sunlight usually need the support of a supplement chosen with your doctor.
Testing and Doctor-Guided Supplementation
This is the part I feel most strongly about. Vitamin D is fat-soluble, which means it is stored in the body and can accumulate, so more is not automatically better, and very high intakes taken without guidance can cause harm.
Here is how I encourage clients to approach it:
- Test before you supplement. A simple blood test shows where you actually stand, so any supplement is based on evidence rather than guesswork.
- Let your doctor set the dose. The right amount depends on your blood level, your risk factors, your other conditions and any medication you take. I do not recommend deciding this yourself from the internet.
- Retest as advised. Deficiency is usually corrected over a period of time, and your doctor may recheck your level to confirm you are in a healthy range and then move to a maintenance approach.
- Consider the supporting nutrients in context. Magnesium is involved in how the body uses vitamin D, and vitamin K2 is often discussed alongside vitamin D for its role in directing calcium. These can matter, but they should be considered as part of your overall picture with your doctor or dietitian, not added blindly.
A sample day that supports healthy vitamin D status might look like this: eggs with wholegrain toast at breakfast, a lunch built around a salad and some fortified yoghurt, grilled salmon with vegetables and mushrooms at dinner, and, in the darker months, a doctor-recommended supplement taken with a meal that contains some fat so it absorbs well.
Common Myths About Vitamin D Deficiency
- Myth: You can fully correct a deficiency through diet alone. Correction: Food helps and matters, but a genuine deficiency almost always needs a supplement chosen with your doctor.
- Myth: More vitamin D is always better. Correction: It is fat-soluble and stored in the body, so excessive doses can be harmful. Dose should follow your bloodwork and your doctor.
- Myth: If it is sunny, you are covered. Correction: In Northern Europe the winter sun is too low to produce vitamin D at all, whatever the weather feels like.
- Myth: Only older people need to worry. Correction: Deficiency is common across all ages, and is especially likely in those who cover their skin or spend most of the day indoors.
- Myth: You do not need a blood test, you can just take a high dose to be safe. Correction: Testing first avoids both under-treating and over-supplementing, and keeps you safe.
A Season-by-Season Strategy for Northern Europe
Because vitamin D in Northern Europe is so tied to the calendar, it helps to think about it across the year rather than as a one-off problem to fix. Your needs and your best strategies genuinely shift with the seasons.
- Spring (roughly March to May): As the sun climbs higher, short, regular exposure of the face, arms and hands without burning begins to help again. This is a good moment to book a blood test if you have felt low through winter, so any deficiency is caught before summer.
- Summer (June to August): This is when your skin can make the most vitamin D, and when many people top up their stores. Enjoy time outdoors sensibly, always protecting against burning and never chasing strong sun or sunbeds. Keep oily fish and eggs in your routine so food continues to contribute.
- Autumn (September to November): Levels that peaked in summer start to fall as the sun drops. This is often when a doctor-guided supplement is reintroduced for those who need one, so you enter winter from a stronger position.
- Winter (December to February): From roughly October to March the sun is simply too low for your skin to make vitamin D at all, whatever the weather feels like. Food and a doctor-guided supplement do the work here, and it is the season when deficiency symptoms most often surface.
Thinking seasonally takes the guesswork out of it. Many people in the Netherlands, Belgium and Germany do best with a steady, doctor-agreed maintenance approach through the darker half of the year.
Who Is Most at Risk, and Why It Is Worth Knowing
Deficiency can affect anyone in this climate, but some people are considerably more likely to run low, and knowing where you stand helps you and your doctor decide whether to test sooner rather than later.
- People with darker skin, because higher melanin means less vitamin D is produced from the same amount of sun.
- Anyone who covers most of their skin for cultural or religious reasons, or who simply spends most daylight hours indoors, including many office and shift workers.
- Older adults, whose skin makes vitamin D less efficiently with age.
- Pregnant and breastfeeding women, who have higher needs during this time.
- Babies and young children, who in many European countries are advised to have a supplement; always follow your doctor's or health service's guidance here.
- People with coeliac disease, inflammatory bowel disease, or liver and kidney conditions, which can affect how vitamin D is absorbed or activated.
- Those living with obesity, as vitamin D can be held in fat tissue and be less available to the body.
None of these is a fault or a failing. They are simply practical reasons to raise vitamin D with your doctor and ask whether a blood test makes sense for you, rather than waiting to feel unwell.
Practical Tips for Building the Habit
Knowing what to do and actually doing it consistently are two different things, especially through a long grey winter. A few small, realistic habits make a supplement and a supportive diet far easier to stick with.
- Anchor a supplement to an existing routine. Taking it with your largest meal of the day, which usually contains some fat, both aids absorption and helps you remember, because vitamin D is fat-soluble.
- Keep it visible. A supplement left in a cupboard is easily forgotten; one kept by the kettle or on the kitchen table is not.
- Batch your oily fish. Tinned salmon, mackerel and sardines are affordable, keep in the cupboard, and make a quick lunch, so you are not relying on fresh fish alone.
- Choose fortified products where they fit naturally, such as certain spreads, plant-based milks and cereals, checking the label for added vitamin D.
- Note the date of your last blood test, so you and your doctor know when it might be sensible to recheck rather than guessing.
Working With Hanzi Nutrition
At Hanzi Nutrition, I support people navigating vitamin D deficiency and wider metabolic health entirely online, in English and Turkish, across the Netherlands, Belgium, Germany and Turkey. This means you can get informed, personalised guidance wherever you are based, without needing to travel.
A typical engagement begins with a first consultation, where I review your history, your symptoms and any bloodwork you already have, and we talk through your lifestyle, sunlight exposure and food preferences. From there I build a personalised plan that strengthens your diet and daily habits in a realistic way. Then we continue with ongoing support, adjusting as your levels and energy improve. Importantly, I coordinate with your doctor and never replace medical care; decisions about supplement doses and any medication stay firmly with your physician, and I help you make sense of it all and follow through.
If winter tiredness and a low vitamin D level are wearing you down, book a consultation with Hanzi Nutrition and let's build a plan that supports you, in coordination with your doctor.
Hanzi Nutrition offers dietitian-led nutrition counselling across the Netherlands, Belgium, Germany, and Turkey, fully online, in English and Turkish. This article is general education and not a substitute for individual medical care. Please coordinate any changes to your nutrition, supplements, or treatment with your doctor.
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