# Vitamin D Deficiency in Switzerland: What You Really Need in Winter

> Vitamin D deficiency affects almost everyone in Switzerland from October to March. Learn why that is, how much you really need and how to counteract it.

With the arrival of autumn and the retreat of the sun, the question of adequate vitamin D supply arises in Switzerland every year. The reduced sunlight during the winter months makes the body's own production considerably more difficult and can lead to a deficiency with far-reaching health consequences.

## Vitamin D Synthesis and the Swiss Winter Sun

The body's own **vitamin D synthesis** is directly tied to the sun's UVB radiation. In Switzerland, due to its geographical latitude, the intensity of UVB radiation from October to March is insufficient to enable significant vitamin D production in the skin. Even in the summer months, factors such as **sunscreen**, clothing or spending time indoors can severely impair synthesis.

## The Role of Vitamin D in the Body

Vitamin D acts in the body much like a **steroid hormone**, influencing gene expression in nearly all tissues. It is essential for the normal function of the **immune system**, the maintenance of healthy bones and teeth and optimal muscle function. It also contributes to regulating the **calcium level** in the blood. A deficiency can therefore affect health in many ways.

## Recommended Vitamin D Intake

The Swiss Society for Nutrition (SGE) recommends a daily intake of **600 IU (15 μg)** of vitamin D for adults. For people over 60, the recommendation is 800 IU. To reach an optimal vitamin D level (target range 40-70 ng/ml), 1,000-2,000 IU per day is often recommended. A **blood test** measuring the 25-OH vitamin D3 level can provide insight into your individual needs.

## The Synergy of Vitamin D and K2

Vitamin D promotes the absorption of calcium in the gut. For this calcium to be properly utilized and reach the bones, however, **vitamin K2** is of crucial importance. The **MK-7** form in particular directs calcium specifically into the bones and prevents its deposition in the vessel walls. Natural sources of vitamin K2 include fermented foods such as natto, but also cheese and butter from grass-fed animals.

**[WOO® Vital Plus](/en/shop/woo-vital-plus-box)** contains vitamin D3 in combination with other micronutrients. Available in our shop.

## Frequently Asked Questions

**What is the best way to take vitamin D?**
Vitamin D is fat-soluble and should ideally be taken with a meal that contains some dietary fat. This considerably improves absorption in the body.

**Can you overdose on vitamin D?**
An overdose is unlikely when sticking to the recommended daily doses. Doses above 4,000 IU daily, however, should only be taken under medical supervision to avoid possible side effects.

**Why is vitamin D especially important in winter?**
Because of the low position of the sun in Switzerland from October to March, the body can hardly produce any vitamin D of its own during this time. Additional intake is therefore often necessary to avoid a deficiency.

## Sources

SGE (2020), Reference Values - Vitamin D.
Holick MF (2007), New England Journal of Medicine - Vitamin D Deficiency.
Webb AR (2006), Journal of Steroid Biochemistry and Molecular Biology - Influences on cutaneous vitamin D synthesis.

*WOO® Vital Plus in the NEMAPO Shop.*