Summary
In Norway, Sweden, Denmark, Finland and Iceland the sun is too weak for part of the year for your skin to make vitamin D, so food and supplements have to carry the load.
The Nordic Nutrition Recommendations 2023 set 10 µg (400 IU) a day for adults and 20 µg (800 IU) for people aged 75 and over or with little sun exposure, with 100 µg as the safe upper limit. Low vitamin D is also linked to poorer sleep, and a meta analysis found supplements improved sleep quality scores.
If you live in Oslo, Stockholm, Copenhagen or Helsinki, you know the feeling: you leave for work in the dark and come home in the dark. Those short days do more than affect mood. For several months a year the sunlight that reaches the Nordic countries is simply too weak for your skin to produce vitamin D. This guide explains why, what the official Nordic advice says, how much to take, and why vitamin D keeps appearing in sleep research.
Why the Nordic winter empties your vitamin D
Your skin makes vitamin D when ultraviolet B (UVB) light hits it. UVB only gets through the atmosphere in useful amounts when the sun stands high enough in the sky. The Nordic and Baltic countries lie between roughly 54 and 71 degrees north, and the Nordic Nutrition Recommendations 2023 (NNR 2023) note that sunlight there is insufficient for vitamin D production for part of the year.
The Finnish Food Authority puts it plainly: in Finland, skin production happens between March and October, peaking in summer. Between those months your body runs on stored vitamin D plus whatever comes from food and supplements. Further north, in Tromsø or Lapland, the window is even shorter.
A sunny February afternoon in Stockholm can feel bright, but the sun is too low for meaningful vitamin D production. Bright is not the same as UVB.
What the official Nordic recommendations say
| Group | Recommended intake (NNR 2023) | In IU |
|---|---|---|
| Adults | 10 µg a day | 400 IU |
| Adults aged 75 and over | 20 µg a day | 800 IU |
| People with little or no sun exposure | 20 µg a day | 800 IU |
| Safe upper limit for adults | 100 µg a day | 4,000 IU |
National advice builds on these numbers and differs in the details. Finland, for example, recommends a daily supplement all year round for people under 18, pregnant and breastfeeding women, adults aged 75 and over, and anyone who does not regularly eat fish or vitamin D fortified foods. NNR 2023 also flags vegans and people who avoid fish as being at risk of deficiency without supplements or fortified foods. Check your own national health authority for the exact advice where you live.
What Finland's fortification policy showed
Finland began fortifying fluid milk products and fat spreads with vitamin D in 2003. A study in the American Journal of Clinical Nutrition (2017) compared nationally representative samples of 6,134 and 4,051 adults. Between 2000 and 2011, average blood vitamin D rose from 48 to 65 nmol/L, and the share of adults using vitamin D supplements rose from 11% to 41%. Among people who followed the dietary advice on milk, spreads and fish, 91% of those not taking supplements reached a level above 50 nmol/L. The lesson: steady daily intake works, whether it comes from food or a capsule.
Vitamin D and sleep: what the research shows
Vitamin D receptors are found in brain areas involved in regulating sleep, and this is one reason researchers have looked at the link.
- Low levels and poor sleep go together. A 2018 meta analysis in Nutrients pooled nine studies with 9,397 participants. People with vitamin D deficiency had 1.5 times the odds of sleep disorders, and higher odds of poor sleep quality (1.59), short sleep (1.74) and daytime sleepiness (1.36). Levels below 20 ng/mL (50 nmol/L) stood out.
- Supplements may improve sleep quality. A 2022 meta analysis in Nutrients found that vitamin D supplements lowered Pittsburgh Sleep Quality Index scores by 2.33 points compared with placebo, with moderate certainty of evidence. Effects on sleep duration and sleep disorders were less clear.
Most of this evidence is observational, so it does not prove that low vitamin D causes poor sleep. In the Nordic winter, short days affect sleep and vitamin D at the same time. We explore the light side of the story in sleep in the Nordic dark season.
How much vitamin D should you take?
- Most adults: 10 µg (400 IU) a day from food and supplements combined, following NNR 2023.
- Little sun, darker skin, aged 75 or over, or no fish: 20 µg (800 IU) a day.
- Known deficiency: higher doses for a period may make sense, but only with a blood test and medical advice.
- Never above 100 µg (4,000 IU) a day without a doctor's guidance.
Getting tested
A 25(OH)D blood test shows your vitamin D status. Finnish guidance uses 50 nmol/L as the target. Testing in late winter, when levels are lowest, gives the most useful picture. Note the units: 50 nmol/L equals 20 ng/mL.
Food first, then fill the gap
Oily fish such as salmon, herring and mackerel, eggs and fortified milk products are the main dietary sources. In practice, many Nordic adults find it hard to reach 10 to 20 µg from food alone through the winter, which is why supplements are so widely used.
Vitamin D in VIT & MIN + CoQ10
VIT & MIN + CoQ10 provides 7.5 µg (300 IU) of vitamin D3 per capsule, or 15 µg (600 IU) at the full two capsule daily dose, alongside 31 other nutrients and 50 mg of CoQ10 as ubiquinol. Vitamin D contributes to the normal function of the immune system and to the maintenance of normal bones and muscle function. The capsules are liposomal, with the nutrients wrapped in phospholipids to help protect them through digestion. If you already take a separate vitamin D supplement, add up your total so you stay within your target. For immune support combinations, see vitamin D, vitamin C and zinc, and for southern Europe, our guide to vitamin D dosage in Greece.
Frequently asked questions
Why is vitamin D deficiency common in Scandinavia?
For part of the year the sun is too low for the skin to make vitamin D at Nordic latitudes. In Finland, skin production happens only between March and October, so in winter the body relies on stores, food and supplements.
How much vitamin D should adults in Norway, Sweden, Denmark or Finland take?
The Nordic Nutrition Recommendations 2023 set 10 µg (400 IU) a day for adults and 20 µg (800 IU) for people aged 75 and over or with little sun exposure. National advice differs in the details.
What is the maximum safe dose of vitamin D?
For adults, the upper intake level is 100 µg (4,000 IU) a day. Higher doses should only be taken with medical guidance.
Can low vitamin D affect sleep?
Studies link vitamin D deficiency with poorer sleep quality and shorter sleep, and a meta analysis found supplements improved sleep quality scores. Most of the evidence is observational, so the link is not proven to be causal.
Should I take vitamin D only in winter?
It depends on your diet, sun exposure and national advice. Finland recommends year round supplements for several groups. Many others take vitamin D mainly from October to March, when skin production stops.
Bottom line
At Nordic latitudes, your skin cannot make vitamin D for much of the year. Aim for 10 µg a day, or 20 µg if you get little sun or are 75 or over, stay below 100 µg, and test in late winter if you are unsure. Better vitamin D status may also support better sleep quality.
Explore VIT & MIN + CoQ10 →Related reading: vitamin combinations for immune support · magnesium for sleep
Sources
- Nordic Council of Ministers. Nordic Nutrition Recommendations 2023: Vitamin D. 2023. pub.norden.org
- Finnish Food Authority (Ruokavirasto). Vitamin D. ruokavirasto.fi
- Jääskeläinen T, Itkonen ST, Lundqvist A, et al. The positive impact of general vitamin D food fortification policy on vitamin D status in a representative adult Finnish population: evidence from an 11-y follow-up based on standardized 25-hydroxyvitamin D data. American Journal of Clinical Nutrition. 2017. doi.org/10.3945/ajcn.116.151415
- Gao Q, Kou T, Zhuang B, Ren Y, Dong X, Wang Q. The Association between Vitamin D Deficiency and Sleep Disorders: A Systematic Review and Meta-Analysis. Nutrients. 2018. doi.org/10.3390/nu10101395
- Abboud M. Vitamin D Supplementation and Sleep: A Systematic Review and Meta-Analysis of Intervention Studies. Nutrients. 2022. doi.org/10.3390/nu14051076
