You make vitamin D mainly through sunlight on your skin. In the Dutch winter, roughly from October to March, the sun is too low and this barely happens. As a result, a large share of women have low vitamin D in that period. One blood value brings this clearly into view.
I notice that many women see the winter tiredness and low mood as a given. Yet a low vitamin D can contribute to it.
Below you walk through the symptoms and the right testing moment calmly.
Why is vitamin D a point of attention in winter?
Your skin makes vitamin D under the influence of UV light from the sun. In the Dutch winter months the sun is so low that this production almost stops. You then live off your stores and off what you get through food and supplements.
That is why the Health Council of the Netherlands advises certain groups to take extra vitamin D in winter. Women with darker skin, who spend little time outside or who often cover up, are more at risk of a deficiency.
Which symptoms fit a vitamin D deficiency?
The complaints of a vitamin D deficiency are often vague: tiredness, a listless feeling and sometimes muscle or bone pain. Because they are not very specific, you easily put them down to the season or to being busy. A pattern that lasts the whole winter is a reason to look further.
Signs that often fit a deficiency:
- Persistent fatigue and a listless feeling
- Muscle weakness or vague muscle pain
- Bone or joint complaints
- A low mood, especially in the dark months
- More frequent colds
Many of these complaints also fit other causes, such as anaemia or a B12 deficiency. That is why a single symptom says little. If you want to look more broadly at the cause of your tiredness, read our pillar always tired: which blood values to test for fatigue.
Who is more at risk of a deficiency?
Anyone can have lower vitamin D in winter, but for some women the chance is greater. That is linked to your skin type, your lifestyle and your age.
You see an increased risk in, among others:
- Darker skin, which makes less vitamin D from sunlight
- Spending little time outside or often covering the skin
- A pregnancy or breastfeeding
- A higher age, due to reduced production in the skin
For these groups the Health Council often advises a fixed supplement. Whether that applies to you and at which dose is best discussed with your GP.
Which blood values give insight?
You bring a vitamin D deficiency into view with one main value, sometimes supplemented with calcium. Vitamin D shows your stores, and calcium sometimes sits alongside it because vitamin D helps with its absorption. The table below sums it up.
| Value | What it measures | What it shows |
|---|---|---|
| Vitamin D (25-OH) | Your vitamin D reserve in the blood | A low value points to a deficiency |
| Calcium | The calcium level in your blood | Completes the picture, as vitamin D supports its absorption |
The value 25-OH vitamin D is the usual measure for your stores. In late winter, often around February or March, it is usually at its lowest. That is exactly when a measurement can give a realistic picture.
Want to test specifically? The B vitamins panel brings vitamin D into view together with other vitamins, so you see the whole in context rather than one isolated number.
When should you have your vitamin D checked?
A lower vitamin D in winter is normal and not immediately a reason for concern. It gets more interesting if your complaints last or if you belong to a risk group. Then a measurement can help to see where you stand.
Consider a check if you recognise this:
- You feel tired and listless all winter
- You spend little time outside or often cover your skin
- You have vague muscle or bone complaints
- You belong to a group for whom extra vitamin D is advised
If your complaints might come from elsewhere, also read vitamin B12 deficiency: symptoms and testing, because B12 also causes tiredness. You always discuss an abnormal result with your GP.
Frequently asked questions
Can I get vitamin D from food?
Some of it, mainly from oily fish, eggs and fortified products, but food usually does not provide enough. Sunlight is the most important source, and in winter that largely falls away. That is why a supplement is useful for some groups.
How much vitamin D may I take?
That depends on your age, skin type and situation. The Health Council gives recommended doses, but too much can also be undesirable. Discuss with your GP what fits you, certainly if your value is low.
When is the best time to test?
Late winter often gives the most realistic picture of a deficiency, because your stores are then at their lowest. If you test in summer, your value can be temporarily higher. Your doctor helps you place the result in context.
References
- Health Council of the Netherlands (Gezondheidsraad). Evaluation of the dietary reference values for vitamin D. The Hague: Gezondheidsraad, 2012.
- Netherlands Nutrition Centre (Voedingscentrum). Vitamin D. Available via voedingscentrum.nl.
- RIVM. Vitamin D and intake in the Netherlands. National Institute for Public Health and the Environment. Available via rivm.nl.
- Thuisarts.nl. I want to know more about vitamin D. Dutch College of General Practitioners. Available via thuisarts.nl.
Every blood test result through Lunara includes a professional assessment by a BIG-registered doctor. For treatment decisions, discuss your results with your GP.
Tagi
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