Short answer: Swedish public-health guidance recommends 10 µg (400 IU) of vitamin D daily for most people aged 2 to 74, and 20 µg (800 IU) for adults over 75. Higher amounts are recommended for people who get little sun, cover their skin, or have darker skin. Between roughly October and March, sunlight in Sweden cannot produce vitamin D in your skin at all — the sun never gets high enough in the sky.
Why Nordic winter is different
Your skin makes vitamin D when UVB radiation hits it. UVB only reaches the ground in useful amounts when the sun is above roughly 45 degrees of elevation. In Stockholm, that condition is not met at any point during the day from around late October to late March.
This is not a matter of it being cloudy or cold, and it is not solved by spending longer outside. During those months the wavelength simply does not arrive. Whatever vitamin D you have is either stored from summer, eaten, or supplemented.
This is why vitamin D supplementation is unusually well-established as public-health advice in the Nordics compared with southern Europe — it reflects latitude, not fashion.
What the official guidance says
Swedish recommendations from Livsmedelsverket, in brief:
- Infants 0–2 years: 10 µg daily, given as drops, from one week of age — for all babies, regardless of feeding method.
- Children and adults 2–74: 10 µg daily.
- Adults 75+: 20 µg daily.
- Anyone who avoids sun, covers most of their skin, or has darker skin: 20 µg daily year-round.
Children up to five who eat little fish or fortified food are also commonly advised to continue drops — follow your child health centre's advice, which will be specific to your child.
Reading the label: IU, µg and mcg
This trips up almost everyone, because supplements use two different units interchangeably. The conversion is fixed:
- 1 µg = 40 IU
- 10 µg = 400 IU
- 25 µg = 1000 IU
- 50 µg = 2000 IU
- 75 µg = 3000 IU
- 100 µg = 4000 IU
- 125 µg = 5000 IU
"mcg" and "µg" mean the same thing. So a bottle labelled 5000 IU contains twelve and a half times the standard adult recommendation — which may be entirely appropriate if a doctor has advised it, and is more than most people need otherwise.
Is more better? No.
Vitamin D is fat-soluble, which means it accumulates rather than being flushed out like vitamin C. The EU tolerable upper intake level for adults is 100 µg (4000 IU) daily from all sources combined.
Genuine vitamin D toxicity is rare and generally requires sustained very high intakes, but it is real — it raises blood calcium, which affects the kidneys and heart. The practical points:
- Add up everything. A multivitamin, a D3/K2 product and a dedicated vitamin D can quietly stack.
- High-strength products (4000–5000 IU) are appropriate when a doctor has identified a deficiency and advised correction, not as an indefinite default.
- If you are unsure whether you are low, ask for a 25(OH)D blood test rather than guessing upward.
Under EU-authorised claims, vitamin D contributes to the normal function of the immune system, the maintenance of normal bones, teeth and muscle function, normal absorption and utilisation of calcium and phosphorus, and normal blood calcium levels. It also contributes to normal immune function in children and to normal bone growth and development.
D2 or D3?
Vitamin D3 (cholecalciferol) raises and maintains blood levels more effectively than D2 (ergocalciferol). D3 is what you will find in almost all supplements. Conventional D3 is derived from lanolin, so it is not vegan; vegan D3 is made from lichen. Both work.
Does vitamin D need to be taken with fat?
Absorption improves when it is taken with a meal containing some fat. Many products handle this for you by dissolving the vitamin in oil — coconut, MCT or olive — in which case timing matters less. Oil-based capsules and drops are a reasonable choice if you tend to take supplements on an empty stomach.
Food sources — helpful, rarely sufficient
Oily fish is the main dietary source: salmon, herring, mackerel, sardines. In Sweden, milk, some yoghurts and margarines are fortified. Egg yolks and mushrooms contribute modest amounts.
Realistically, reaching 10 µg daily from food alone requires eating oily fish several times a week, every week. Achievable for some households; not most.
What about vitamin K2?
Combined D3/K2 products are popular, on the reasoning that K2 helps direct calcium into bone. The evidence is promising rather than settled. One thing that is not in question: if you take a vitamin K antagonist such as warfarin, vitamin K supplements interfere with it directly. Speak to your doctor before taking any K2 product.
What we stock
Across our immune support range:
- Around the standard recommendation — Solgar Vitamin D3 25 µg (1000 IU), Elexir Vitamin D3 1000 IU. A sensible everyday winter choice for most adults.
- Mid-strength — Holistic Vitamin D3 2000 IU (in capsules, oil capsules and 360-count), Skip Vitamin D 50 µg, Holistic Vegan Vitamin D3 2000 IU.
- High-strength — Elexir Vitamin D3 5000 IU, Great Earth Vitamin D3 75 µg, Elexir Vegan D3 4000 IU. For use when advised.
- Liquids and drops — Holistic D3-Vitamin Dropper and Vitamin D3 Liquid, useful for children and anyone who struggles with capsules.
- Children — Great Earth Vitamin D Kids chewable tablets, in our children's range. Check age guidance on the pack.
- With K2 — Elexir Vitamin K2 & D3, Holistic K2+D3 in Oil, Upgrit Vitamin D3 + K2.
The practical takeaway
If you live in Sweden and take nothing else, a modest daily vitamin D from October to March is the single best-supported supplement decision available to you — for most adults, 10 to 25 µg. Older adults, and anyone with limited sun exposure or darker skin, should be at the higher end year-round. If you are considering anything above 100 µg (4000 IU) daily, get tested first and involve your doctor.
Food supplements should not replace a varied, balanced diet and a healthy lifestyle. Always read the product label and follow the stated directions. This article is general information, not medical advice — seek advice from a doctor, midwife or child health centre for infants, during pregnancy or breastfeeding, alongside prescription medication, or when managing a medical condition.
