Vitamin D is unique — the only vitamin the body can produce itself under sunlight. Yet in Lithuania the sun is sufficient for only 4-5 months a year. According to studies by the Lithuanian University of Health Sciences, up to 80% of Lithuanians have insufficient vitamin D levels in winter, and in some groups — 90%+. This is no small matter — vitamin D plays a role in bone health, the immune system, mood and muscle function. In this educational article — why people are deficient, how to get tested, how much to take and which supplement is best. This article is informational and does not replace consultation with a doctor.
What vitamin D actually is
Technically — vitamin D is not a vitamin but a hormone precursor (prohormone). The body converts it into the active hormone calcitriol, which acts not only on bones but controls the activity of 1000+ genes.
There are two main forms:
- Vitamin D2 (ergocalciferol) — of plant origin, less effective
- Vitamin D3 (cholecalciferol) — of animal origin, better absorbed — this is the form the body produces itself through sunlight
Modern consensus: D3 supplements are better than D2.
Why people are deficient in Lithuania
1. Geographical position
Lithuania lies at ~54-56° northern latitude. Modern UVB solar radiation (which is needed for vitamin D production) is sufficient in Lithuania only:
- From May to August — between 10:00-15:00
- In April and September — with limited effect
- From October to March — almost no D synthesis
This means: for 7 months of the year Lithuanians do not get enough vitamin D from the sun, even if they were outside all day.
2. Modern lifestyle
- 8-10 hours of office work indoors
- Schools, universities in closed premises
- Use of sunscreens (SPF 30+ blocks 95-99% of UVB)
- Clothes that cover most of the body surface
- Less outdoor time in summer than a few decades ago
3. Food contains little vitamin D
The traditional Lithuanian diet has little vitamin D:
| Food | Vitamin D (IU / 100g) |
|---|---|
| Salmon (wild) | 500-1000 |
| Salmon (farmed) | 250 |
| Sardines | 270 |
| Egg (whole) | 40 |
| Milk (fortified with vit. D) | 50-100 |
| Shiitake mushrooms (UV-exposed) | 200-1100 |
Even eating well, it is hard to get 2000 IU per day from food.
4. Dark skin
Darker skin blocks UVB more strongly — so people with darker skin need 3-6x more sun time than those with lighter skin. In Lithuania this is relevant to a smaller extent, but it is worth knowing.
5. Age
With age, the skin produces less vitamin D from sunlight — a 70-year-old produces ~25% of what a 20-year-old does.
Vitamin D deficiency symptoms
The problem — symptoms are often subtle and non-specific:
Common
- Mild drowsiness, lack of energy
- Frequent colds
- Muscle pain (especially in the back, shoulders)
- Difficulty getting up in the morning
- Mild depression or "blue mood" in winter
- Slow-healing wounds
Moderate deficiency
- Bone and joint pain
- Hair loss
- Weak immune system
- Heavier sweating (especially of the head)
Severe deficiency
- Osteomalacia (muscle and bone pain)
- Severe depression
- In children — growth disorders
For seasonal affective disorder (SAD) — winter depression — vitamin D deficiency is one of the main causes in Northern Europe.
How to get tested
One test — a 25(OH)D blood measurement. In Lithuania it costs 15-25 € in private labs and may be requested in state ones if there are symptoms.
Interpretation of results:
| Level (ng/mL) | Classification |
|---|---|
| < 12 | Severe deficiency |
| 12-20 | Deficiency |
| 20-30 | Insufficient (but not deficient) |
| 30-50 | Sufficient |
| 50-80 | Optimal |
| > 100 | Too high (toxicity) |
The average Lithuanian level in winter — about 15-22 ng/mL. That is, most Lithuanians have insufficient levels in winter.
How much to take
This question has a spectrum of opinions:
Official recommendations (Lithuania)
- Adults: 600-800 IU per day
- Older adults (60+): 800-2000 IU per day
Modern research consensus
- Most adults: 2000-4000 IU per day maintains 30-50 ng/mL
- If deficient: 5000-10000 IU per day for 8-12 weeks, then a maintenance dose
- Target level: 40-60 ng/mL for most
Practical advice: if you have not been tested, 2000 IU per day is a safe maintenance dose for most adults in Lithuania, especially from October to April.
Maximum safe doses
- Without supervision: 4000 IU per day
- Under medical supervision: up to 10 000 IU for a short time
- Toxicity — over 50 000 IU per day for prolonged periods
Which supplement is best
D3 or D2?
D3 — almost always. Better absorbed, maintains levels more steadily.
Tablets or drops?
Both work. Drops (liquid) — better absorption, especially for older adults. Tablets — more convenient.
With vitamin K2
Many modern D3 supplements add K2:
- D3 raises calcium in the blood
- K2 directs calcium into bones, not into vessels
- Without K2 — possible risk of vessel calcification
Modern consensus: D3 + K2 is better than D3 alone.
With healthy fats
Vitamin D is fat-soluble. Taken with food that contains fat — much better absorption. Example: with breakfast (egg, avocado) or lunch with fish.
Specific groups
Children
- Infants (0-12 months): 400 IU per day — recommended in Lithuania from birth
- 1-12 years: 600-1000 IU
- Teenagers: 1000-2000 IU
Pregnant women
1500-2000 IU per day. Deficiency is linked to pregnancy complications. Consult your doctor.
Older people
2000-4000 IU per day due to lower skin synthesis and the relevant osteoporosis risk.
Vegans / vegetarians
Supplementing is almost essential — most D3 sources are of animal origin. There are vegan D3 supplements (from lichen).
Darker skin
Higher doses (3000-5000 IU) may be needed.
Vitamin D and other systems
Immunity
Vitamin D plays a role in regulating the immune system. Studies show possible effects on the severity of colds, flu and COVID-19.
Hair
Vitamin D plays a role in the hair follicle cycle. Deficiency is one cause of hair loss. More in the article on hair loss.
Mood
The brain has vitamin D receptors. Deficiency is linked to depression risk, especially seasonal affective disorder.
Hormones
Vitamin D plays a role in testosterone and oestrogen production. More in the article on women's hormonal balance and the article on men's energy.
Stress response
Vitamin D is involved in cortisol regulation. More in the article on cortisol.
Summer sun experiment
Practical test: ask yourself a few questions about summer:
- How many minutes a day am I outside without sunscreen, with arms and face exposed?
- How many days a week?
- Between 10:00-15:00, when UVB is strongest?
Optimal: 15-30 min per day × 3-4 times a week × June-August = 4-5 months sustained, the level reaches 40-50 ng/mL.
But even then — the level drops in winter. So a supplement from October to April is recommended for almost everyone in Lithuania.
Caution
Vitamin D is safe up to a certain level:
- Certain medications — interact with vitamin D (blood thinners, steroids, some heart medications)
- Sarcoidosis and other granulomatous diseases — vitamin D can be dangerous
- Hyperparathyroidism — with caution
- Kidney stones — with a doctor
Toxicity arises only from supplements (the sun does not cause it) and only at long-term doses of 50 000+ IU.
From our range
Vitamin D is a frequent ingredient:
- In general health support complexes
- In immune-system formulations
- For hormonal support
Food supplements do not diagnose, treat or prevent disease. Talk to your doctor, especially if you take medication.
Frequently asked questions
Are 80%+ of Lithuanians really deficient?
According to LSMU and other studies — yes, in winter. In summer levels rise, but still 30-40% remain at insufficient levels.
Is it better to get vitamin D from the sun or from supplements?
The sun — natural, but not enough in Lithuania. You need both: sun in summer + supplements in winter. The ideal scenario.
Does sunscreen really block vitamin D production?
Yes. SPF 30 blocks ~95% UVB. SPF 50 — ~98%. Practically — 10-15 min outside without sunscreen (on arms, legs, not face) provides D production; then you can apply sunscreen.
Vitamin D tablets or gummies?
Both work, but gummies often contain sugar. Tablets or drops — simpler and more economical.
My test showed a normal level, but I feel D symptoms. What is going on?
"Normal" lab ranges start at 30 ng/mL — but 30 is just "insufficient". The optimal level for most is 40-60 ng/mL. If you have symptoms with 30-35 ng/mL — raising the level to 50 may help.
How long does it take to see the effect?
First effects (energy, mood) — 4-6 weeks. Full optimal level — 8-12 weeks if deficient.
Summary
Vitamin D in Lithuania is a real challenge — geographic position, modern lifestyle and food do not provide a sufficient level. From October to April — a supplement is recommended for almost everyone in Lithuania. D3 + K2 form with healthy fats — the best. 2000 IU per day — a safe maintenance dose; if deficient — 5000+ IU for 2-3 months under medical supervision. In summer — 15-30 min of sun without sunscreen 3-4 times a week. It is worth checking your blood level at least once a year, especially in spring (the lowest point). More on other minerals — in the article on magnesium.
This information is educational in nature and does not replace professional medical advice.
